Piston vs Diaphragm 1st Stage - Scuba Tech Tips: S07E01
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- เผยแพร่เมื่อ 1 ต.ค. 2024
- Scuba divers argue about many subjects and piston vs diaphragm is a long running one. Alec takes apart a piston and diaphragm 1st stage showing their internal parts and the key differences between them.
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This video advocates piston quite haeavily, but there are good reasons why diaphragm 1st stages are used (e.g. cold waters to avoid free flow). I'm not going to argue for one or another, everyone should decide on their own, but this video does not portrait the entire picture, so you should look for other information sources in order to get entire picture. I know, that Alec mentions that there's more to this topic, but if I were clueless then I would buy piston without thinking after watching this video ...
That wasn't my intention SS. Many divers shun the piston. I was just trying to even the field.
BTW, the piston is just as good in cold water as the diaphragm. Note the impressive 40 year record of the cold water champ - the Sherwood Blizzard. The first USD Aqua-lung Calypso was a piston and it had a great reputation for use in cold water.
Neither style has any advantage over the other in terms of performance in any environment so it comes down to cost, service and reliability.
Frankly, the 1st stage is highly overrated. It performs a very perfunctory job - open/close, open/close, repeat indefinitely. Either style will do the job well.
Thanks for watching.
Alec
Thank you for pointing out Sherwood Blizzard, I didn't know that one. In any case, there are reasons why dry chambers have been introduced, but there's always also trade-off between various aspects. The only question is what's more important for your diving and what diving setup you're diving with. However, by all means, it was meant as constructive criticism and it would be appreciated if you can perhaps produce another video diving deeper into this topic in order to portrait the entire picture. I really enjoy watching your videos but I had an urge to point out that this video was produced with sort of bias (not obvious from the very first glance). In any case thank you for clarification and looking forward for more content from you.
Kind Regards,
Peter
@@SeekerOfTheAbyss I've had my Blizzard since 1986, when I used it for ice diving and wrecks in Michigan. Never once had a problem with freeze-ups or free flow. Had it rebuilt in 2018 with new, upgraded parts in the first stage. Still works like a champ, but want a newer, slimmer second stage.
So many decisions to make on gear.
Hi Alec, Had a gf who used a diaphragm. kidding. Now i know the difference between 1st stage regs. Your a cornucopia of knowledge, i truly appreciate your entertaining SCUBA videos. Fun to watch while learning. Your students must have respected you and still think of you with fond memories. Best Regards
Some did. Some were experts even though they'd never been underwater. Those ones didn't do well in my classes.
You know what I mean.
Alec
Great video my friend. I'm starting to service regulators at are local dive shop. I love piston and been diving it for 25 years. They are so easy to service. Keep up the great videos. Show us how the old 2 hose regulator works. And inside guts. Montana Mike.
A piston regulator is a service technicians dream come true - 4-5 parts, mostly O-Rings, no adjustment - it couldn't be easier.,
I'm getting to the adjustment of regs first and then I'll start looking at different models including 2 hose.
Take care Mike.
Alec
I think diaphragms are still around because they can be more easily environmentally sealed. At least, sealing is their main line of marketing. I know some pistons also claim environmental sealing but their marketing material seems to be trying really hard to convince us that it is as good as that of diaphragms.
You may be right about the marketing slant. Since diaphragms have been around so long it's natural for piston manufacturers to try to persuade divers that their regs are as good or better. That ought to change as it becomes more accepted that pistons are equal to diaphragms in performance and perhaps better in other ways.
Thanks for watching.
Alec
who is best in extreme cold ? like if you dont live in florida where the winter is 70 f .. but lets say norway where surface temp is more like -4 f ? the regulator i use is
specifically made for extreme cold contidions. and its a diaphragm.
Dry air bleed first stage vs sealed? Concerns or thoughts?I think I was going through withdrawal without new tech tips, thanks for keeping them coming!
The unique Dry Air Bleed design developed by Sherwood and now used on their Genesis 1st stage is excellent. I'd need a few minutes and a whiteboard to explain it and might just do that since it's so neat, simple and effective. Essentially it allows the first stage to react to the water pressure without letting any water inside - unlike any other regulator.
So called sealed first stages try to accomplish the same by placing a rubber cap filled with silicon oil over the first stage. It works to some extent but also introduces other problems such as reduced sensitivity, increased maintenance cost and potential corrosion problems. I may do a video on that topic as well to explain some of these ideas. Watch for something called Cold Water Regulators.
It's time for a story - the idea of sealing the first stage is not new at all. Before most of you were divers, say in the 60's, it was pretty common for us to seal our first stages when diving under the ice. I am from Canada remember! We didn't have any fancy Dry Air Bleed regs or Sealed 1st Stages so we made our own. It was simple job. We filled a condom with alcohol, usually Gin, and carefully put the first stage into the Gin and pulled the condom around the first stage. Then we held it all together with rubber bands (this was pre-Duct tape). If you've followed this so far you can see that the entire hollow of the 1st stage was now full of gin and the gin was held in by the condom. No water could get into the reg. I should have patented the idea at the time but was having too much fun to think of that. Soon Poseidon and then much later Aqualung came up with the same idea using a proper rubber cap and a clamp to hold it in place.
So you see that Gin and condoms are a natural combination for divers too.
Thanks Joe.
Alec
Very interesting!! Thanks so much for all the time you take to answer peoples questions, I (and everyone else I'm sure) really appreciate and enjoy the info and stories!
neat story as always! yes please do explore environment seals some more... I have the option on mine (looks like another rubber cap and longer piston) and was wondering about having no water enter the mechanism (already membrane based so little corrosion exposure vs regular piston ?)
Hi Alex, excellent video like always. I recommend you to all my students for you experience and non biased opinion. Keep up the good work.
Thank you. I will try my best to never let you down.
Alec
Hi Alec, At about 330 ft underwater the water pressure is 150 psi. So I am assuming that deeper than this a first stage that delivers 150 psi will no longer work. Do divers who go deeper than this have to adjust their first stage to supply higher pressure? Or does the first stage supply 150 psi relative to the ambient?
Thanks!
Mike
Exactly Mike. The first stage provides air at 150psi ABOVE AMBIENT!
That's why all regulators have a hole or holes in the main body to allow water to enter and act upon either the piston or the diaphragm. The regulator is set to 150 and any water pressure is added to that. Regardless of your depth (pressure), the first stage provides air at 150psi above that pressure. Hence it works perfectly at any depth.
In theory your regulator would work perfectly well during a dive on the Titanic - roughly 2 miles down. That's good to know because you'd have other concerns to address if you were down there! You don't need your reg screwing up!
Take care.
Alec
Alec, if you ever decide to get a group together to go dive the Titanic, can I be invited along please?
With the small jack yves mention...can you make a new series on the history of scuba, how it started when, by who, different systems, the first dive tables etc...
That would be great information for everyone, thank you,
Wow! That would keep me busy for about a year.
I'll keep throwing in little bits here and there when appropriate for now. Maybe eventually I'll be able to coalesce them into a video.
Thanks for watching.
Alec
Hi Alec, you say most first stages nowadays are piston based (@2:07). Not sure if that is completely correct. If I look at Apeks, Aqua Lung, Mares the majority if not all of their first stages are Diaphragm. The only exception is Scubapro who indeed mostly make piston based first stages, which stands to reason as they have always been the biggest in that area as far as I know. Of course things may be different on your side of the big pond and I have to admit that I have no insight in the other brands that are out there but these are the major brands in Europe.
Apart from that, I do agree that in the end it doesn't make a lot of difference, they only have to do 1 thing and do it well. Most important thing is that the first and second stage combined make an easy to breathe fit for your purpose system.
It's hard to know for sure which style is most common. I suppose one could look at all the different brands and add them up but to what benefit. As you say, they both do a good job.
Sherwood (big in North America), Genesis and Atomic only have pistons.
Cressi, Oceanic, Scubapro, Hollis, Beauchat and even Mares offer both piston and diaphragm.
Aqualung has has pistons in the past.
Originally the piston was favored because it was cheaper but now it has become technically equal in all respects to the diaphragm. It is not possible to detect any difference between them with respect to breathing characteristics.
It's often a choice based on what your LDS or your dive buddies or your instructor favors.
Take care.
Alec
Would love to see a video (or two videos) on how each style works, and detailed pros and cons (is one better for cold water, etc). Great videos!
I'm planning on that. There seems to be a lot of divers interested in learning how these things work and there's a real lack of easy-to-understand videos.
Thanks for watching.
Alec
Agree with John, would love to see that. Tks Alec for another great tech tip.
And another vote for how each style works.
Very Nice presentation. Explained it very clearly. Thank you.
I'm glad you enjoyed it. I hope you picked up some ideas.
Alec
Don’t worry my brain does the same and you remind me of my self teaching fitting machining and welding love ya videos
Why not compare a Scubapro MK25 piston to an Apeks US4 diaphragm for complexity vs simplicity ?
The Scubapro MK25 has been around for many, many years. So long that it's become their most famous regulator.
What's not remembered, or maybe not known, is that is has changed over the years. Most of the changes were to correct issues, some performance issues, some reliability issues and some maintenance issues. It is a very unusual design that employs a 2-piece piston (actually 3 piece but you cannot separate the stem from the head easily) and then they added a second piston head under the first so they could install 2 main O-Rings. Now a simple piston with 1 O-Ring has become a 2-3-piece piston with a second head and 2 O-Rings!
In each case these changes were to improve reliability. For example, the second O-Ring was added because there was an issue with the single O-Ring blowing our. That was often caused by poor assembly procedure but it was a problem anyway and they solved it by adding parts. Then they added some buffers - sponge rings around the piston stem, at one time as many as 3, (I think it's back to one now) in an effort to stop noise coming from the first stage, either whistles or rattles. These were marketed as improvements but were actually necessary to address problems.
The balance chamber on the MK25 is another interesting story. I think it now comprises about 5 parts (most pistons work well with 1 O-Ring). Then add their replaceable HP seat with its own O-Ring, adjusting screw, pad and threaded cap and you have a piston regulator that has as many parts as a diaphragm.
However, it's a great regulator and I've used one a lot and sold hundreds. I've also serviced thousands but that's another whole story. They're not hard to service but they do require great care and lots of practice to do it properly.
So now what you've done to me Bumble is take a very sophisticated (read:complicated) piston regulator and compared it to a very simple, straight forward diaphragm. To use your own words, that's an unfair comparison.
However, even with that, a complete strip of both regs will show a similar number of parts.
The US4 is described by Apeks as a "warm water reg, lightweight and light duty'. I'm not in complete agreement with that. Not having an environmental seal does not mean it's no good in cold water. It does mean that the diver has to exercise care in cold water as per my recent video on cold water diving. And in my books, having fewer parts does not mean it's less rugged - just the opposite.
However, It really does not compare to the incredible performance of a MK25. It would be a favorable comparison to an Oceanic Sport reg and I mean in terms of sophistication (neither reg has much of that!!) and performance.
Talk again soon.
Alec
From a very old ad for a seagull outboard "what's not there can't go wrong"
I like that Thomas. Good one. I'll use that in the future.
Alec
nice to see you again. they always tell me it depends on the water temperature one of them is less chance to get stock in cold water . but since my dives are all in tropical water it doesn’t make any differences
+1 I also want to know.
We have a saying in the military, "keep it simple, stupid."
That works in many daily life situations too.
A
New workshop?
You can build a new regulator with all of those spare parts on the wall!
Yep! I upgraded the old place - new benches, new test equipment and I brought the service parts closer to the bench where I need them.
We service many different brands and they all have their own parts. It can get confusing.
Looks good though huh?
Alec
I thought you sold Scuba 2000 and retired, and only came into the shop from time to time to do videos?
Love your videos Alec. Makes my science of diving course more understandable with your videos.
Great to hear!
Hi Alec, greetings from Norway.. Thanks for a excellent video. I was wondering if there is a difference between piston and diaphragm 1st stages when it comes to freezing and salt water intake. Here in Norway the temperature most often during the winter drops down to 35 degrees and below, which make the 1st stage prone to freezing. My APEKS not so much and there are several other more protected against it, but is there any difference between a piston and diaphragm? And again what if water comes in, lets say to forget to close the lid after a dive and soak it in to water, which is better to service? Logic tells me it is the one with the fewer parts.. Anyway, thanks to you and Kevin for yet another excellent video, keep em coming.. PS.. You already did a video about adjusting the 2nd stage, but I would rather know why a 2nd stage makes noise, kinda like a snoring sound when you breath in.. I suspect the venturi valve (is that what it's called?) making such noise, but kinda feel it does not make any difference moving it, it only free flows easier in water.
Jeez Tom - one question at a time OK??
1. Certainly the piston is easier to service. Every serviceman would agree. It's also easier to tune (most cannot be "tuned") and it's
cheaper too.
2. Which is better in cold water? That's a debate that has and will rage forever. You need to know that a regulator really doesn't
freeze. It's made of brass, stainless steel and plastic - none of which freeze. They're already solids.
What 'freezes' is the water in the air in the regulator. As the reg is used in cold water it gets very cold, much colder than the
surrounding water. That's partly because of the cold water and also because of the adiabatic (look it up) temperature drop
resulting from the pressure change within the reg. When the temperature reaches the dew point of the air (the temperature at
which the water in the air condenses) water freezes on the high pressure seat of the first stage and prevents proper closure of
the seat. The reg free flows. Of course the increased air flow from the free flow exacerbates the temperature drop, more water
freezes, more ice builds up, the seal won't close at all and you have a major free flow which we interpret as a freeze-up.
This process is the same in any regulator, piston or diaphragm.
Keeping water out of the body of the reg by using an 'Anti-Freeze kit' or any other of the dozen methods sold as cold water
prevention is a fine idea but since that is not what causes a freeze-up, they are largely a cosmetic or marketing thing.
The regulators with the best reputation for good performance in cold water are the Poseidon Cyklon 300 (no longer available new), the Sherwood Blizzard, the Sherwood SR2 and the Scubapro MK25 (with the S600 second). 3 of these are piston style and none use any special anti-freeze system. Lots of others are good too but, regardless of what any diver will say, no reg is freeze-up free. That is, every regulator will freeze under the right conditions - yes guys, even double hose regs will freeze. I speak from experience on that!
Preventing a freeze-up is a combination of actions that the diver can take (or not).
a. Keep the regulator warm right up until your enter the water. If the 1st stage is warm it takes longer for it to cool in the water and
that will delay the likelihood of freezing.
b. Be sure the air is as dry as possible. Air standards require a dew point of -65 degrees fahrenheit. A good dive shop will give air
with a dew point of -90 to -100 degrees fahrenheit.
c. Don't allow any air to pass through the reg until you are under the surface. Don't test your reg on the surface. You should have
done that before in a warm place. Don't breathe through it or blow up your BC or Dry Suit until you are down. As soon as air
passes through the reg the temperature drops rapidly due to the adiabatic effect. When ice diving, I keep my tank and reg
system in my hot car until ready to jump in. The I put it on, slip into the water, take a big breath from the air, put the reg in my
mouth and drop down as quickly as possible. The first time I breathe underwater it's an exhalation and I'm down 10'. Realize
that the water is warmer than the air and higher than freezing temperature.
d. Try to breathe slowly and steadily underwater - no sudden big inhales or long blasts on the LP hose.
e. Don't use your Safe Second (if possible). that's almost a guaranteed way to freeze up a reg.
3. Your reg is very sensitive. When you inhale it tries to give you lots of air but you don't want lots, so it has to stop delivering air,
but you're still inhaling so it opens wide again, but it's too much air again so it has to stop, but you're still inhaling so it has to
open again and this process continues accompanied by a farting sound from the rubber diaphragm as the reg opens and closes
while trying to decide how much air you want. If you take a sudden big breath, there is no burping sound. This only occurs on
the surface. Water muffles and it also softens the opening and closing underwater. You're reg is doing its job.
Whew! Can I rest now? I'm old Tom.!
Hope this helps or at least gives you something to think about.
Take care.
Alec
Dear Alec, and you wonder why a package arrived for xmas. You rock!! I will however apply the geriatric approach next time with one question he he, but you inspire me to ask question so... Old? Not at all, think you still look young to this day. Also couldn't guess your age if I tried. Send my greetings to Kevin and your better half (also nice kill btw, you can add to that too). Thank you for this long and excellent well informed answer, learned a lot and also helped for sure! Take care! - Tom
to me this not the construction principe that dictates the capacity to resist freezing, it is the capacity to transfer heat from the environment to the pressure change area of the first stage, with a so abrupt pressure change, it is sure that the temperature of the decompressed air drops well below the freezing point so any trace of humidity will freeze even in summer, when the water temperature is high, say 50 degrees and over, the surrounding water gives sufficient heat to the first stage body to prevent the accumulation of ice, when the temperature of the surrounding water goes near the freezing point, the heat transfert is greatly reduced so the ice can accumulate at the decompression point and this impairs the seating of the high pressure seat.
I 've saw an industrial application where a fast cycling pneumatic cylinder was freezing in the mid summer temperatures even if the pneumatic system was equipped wiyh a refrigerated air dryer, the solution we chose was to install a 250 watts heater on the cylinder cap to prevent that.
I had my Genesis Prana Reg set serviced by my shop. The Associate attached to a cylinder tot Test. Good thing he did. The First Stage Blew Out. Making a Loud Pop. The Associate tried to tell me I had a Diaphragm. I remember reading it is a Piston. This was after accident during the AOW Cert Dives on Aug 3.
That is not a problem anyone should have. Hope they fixed it to your satisfaction.
A
@@AlecPeirceScuba_SeaHunter I'm Waiting for the Shop to contact me. Good thing I used a Rental unit on the Deep Dive portion of AOW.
Just magnificus! Thanks!
Thanks K.
Alec
but diaphragm regulator is better for cold water especially if it is environmental sealed.
Not really better, just different. The piston has 2 moving parts, the piston and spring while diaphragms have more. Cold water does not tough either system to its a preference on which style you like.
A
As always great informative video Alec.
Thanks Mule.
Alec
Alec, I'm just getting started in diving, and have been watching a lot of your videos and had one that id like to see: Balanced vs unbalanced regulators, and their internal differences
The internal physical differences between regular and balanced are slight and hard to spot if you do not know what to look for.
I have made a video on regular versus balanced regulators recently.
Unless you purchase the cheapest regulator available today, it's almost guaranteed to be balanced.
Thanks for watching.
Alec
Love your vids Alec, I have learned a lot from your channel. When researching regs I had a lot of people recommending the MK17 over the MK25 when looking at SP regs. Most felt that the sealed aspect along with its cold water performance and reputation for reliability put it at an advantage over the MK25.
The MK17 is a good reg too. It's not been around nearly so long as the MK25 but it has earned a good rep.
The MK25 has some features that help reduce the likelihood of freezing too. You can read about them on their website.
Actually it was a piston reg that we used a condom on. It's very easy to seal.
Thanks for watching.
Alec
Alec Peirce Scuba You know you have to do a video on how you sealed a piston reg with a condom!
@Robert Emmerich Hi! I own a Mk17 and also I have tried the Mk25 a couple of times. Couldn't tell the difference, apart from the big deal on having my Mk17 serviced. I love the Mk17, but I certainly see a lot of advantages on the MK25. My best regards!
The 1st stage is kind of like the reduction gearing on a turboprop engine.
Uh. Yeah sure. It a way. The idea is the same but in practice it's much different of course. One is mechanical. The other is pneumatic.
Thanks for watching.
Alec
This is an unfair comparison.
It compares the simplest piston regulator to one of the more complex diaphragm regulators. A more appropriate comparison for a simple diaphragm regulator would be a Conshelf 14, early Aqualung Titan or a Mares 12.
It also ignores performance … an unbalanced piston regulator is a poor performer, especially at depth and as tank pressure decreases.
Made me lose some respect for you Alec.
A "complex" piston regulator? I'm not sure what that would be. Be design they are simple - a piston, a spring and, and, and, Oh Yeah - 2 O-rings. A fully balanced, full feature piston regulator has, wait for it, a piston, a spring and 2 O-Rings. The balancing of a piston regulator is simply a different air flow through the piston. There's no additional parts or complexity.
The Conshelf 14 (great reg BTW, serviced hundreds of them) still has many more parts that a comparable piston. Both the Titan and Mares MR12 are more complex than the Conshelf. In my video, I did not show all the parts of the diaphragm regulator. There are actually more inside. I couldn't find a standard diaphragm on a moment's notice so I used a balanced model but I countered that by not showing some parts. The comparison is quite valid. I have no agenda and try to make any such comparisons completely fair. The Conshelf 14 has a threaded adjustment cap, spring, diaphragm pad, diaphragm washer, diaphragm, pin pad, pin, moveable seat and another spring - not counting the filter and clip which is the same for both. The Mares MR12 is identical.
I don't want to argue with you but it is a simple fact that any piston reg will be simpler in design than any diaphragm reg. It just takes more parts for a diaphragm reg to sense the water pressure and deliver that action via a pin to the moveable seat.
My only real issue with your comment is that a standard regulator (as you call unbalanced) is a poor performer. The balanced design offers some advantages and some of those advantages may be interpreted as performance related but, for recreational divers in a recreational dive environment, it is not correct to say that a standard regulator is a poor performer. I've made clear that a balanced regulator is preferable given a choice and maybe even essential if diving deep, in cold water or situations where a higher flow air flow is required, but a better regulator?? Everything compared - cost, maintenance, weight, reliability, performance, etc, - the standard reg measures up very well.
I should make clear my objection to the description of a standard regulator as an unbalanced regulator. The two terms describe the same reg design. Realize that at one time, in fact for MOST of the history of scuba diving, standard regulators were the norm. There was no choice. Regulators were just regulators. Then my friend Sam Lecoque designed the first balanced regulator, which BTW, were shunned by divers for a long time. Now we have a choice. The right reg for the right diver based on his needs.
Sorry about the respect thing. May I suggest that you take apart a piston reg and a diaphragm reg as I did and look at the pile of parts - standard or balanced. Hopefully you'll agree that one is simply simpler, which was my whole point.
I avoid the use of the word 'better' in my videos unless there's clearly a important difference. If you re-watch it I think you'll find I did so in this vid too.
Thanks for your input Bee.
Alec
Alec, I own and service sets of Scubapro MK25/S600 and Apeks DS4/XTX40 regulators.
The last time I did the MK25 I recall it had at least 2 o-rings just on the top of the piston. Then there bushing rings, around hp o-ring in the piston shaft, a high pressure plug on one end and another plug on the other end with more internal springs on the hp side too. The MK25 is complex and finicky to service and requires special tools to insert bushings, bullets to insert piston etc.
An Apeks balanced diaphragm regulator is, by comparison to a MK25, very simple to service. My DIN version can be serviced with just 4 tools: 2 hex spanners, an o-ring pick, and c-pin spanner.
And the Apeks is a better [performing] regulator ;)
BTW, the Titan is internally identical to the removable crown version of the Conshelf.
Also, Ted Eldred in Australia developed a balanced diaphragm regulator (Porpoise Universal) around 5 years before Sportsways was founded.
I agree until you talk about a balanced piston regulator. They are complicated with many parts.
Only a little more complicated. Watch S08E14 How A Piston Regulator works for some insight. Thanks for watching mate.
I was talking about the Scubapro MK25
hi Alec.
i am currently in the market for my first regulator. (Yeay)
after watching your video.
im sold on the PISTON reg.
now everything im reading is that piston regs are not generally used for cold water.
That being said. im not intrestead in ice diving.
how ever. will be diving our Ontario lakes though out the summers.
so my question is if a piston 1rst stage isint ideal for cold water.
how cold are they talking about. can i go to 130 feet in ontario lakes or can they still freeze up even though its summer?
Or is any of this even an issue.
really intrestead in what you think before i make a decision. ..joel
This guy explains things well
I explain things so well even Kevin can understand it!!! HA HA
A
thanks, really love your videos
Good to hear from your Karl.
Take care.
Alec
I am a commercial shellfishing diver, stirring up the bottom, diving year round so prefer the diaphragm. But to reduce wear and tear I use my piston MK20 from May to September. Then switch to my Apeks ATX200 October-April. Shwiinng!!
Hello! Mr. Alec Peirce ... A warm greeting from the city of Santa Cruz de Barahona, Caribbean coastal city in the Dominican Republic, for less than a year my employment contract ended and I returned to this region that is my hometown for the purpose of enjoy this area of great beauty and natural wealth, in this free time I spend my time to detect metals and I have a great interest to explore shallow beaches and spas in order to get something of value and thus acquire detector equipment metals that allow me to explore galleons and shipwrecks that are found throughout this southern area ... my interest is to have the basic knowledge in principle for a dive that does not exceed three meters deep .... In this part of the island it is impossible to get a school or course where you can learn everything related to rewarding and sometimes complex world of recreational and professional diving ... But thanks to you, your videos, explanations and good guidance cause confidence and security, Go ahead when you buy my first dive unit and make my first dives I know I will be totally familiar ... My respect for you and my greetings from the Caribbean Coast of the Dominican Republic ... Thank you!
a bit off the subject but I noticed one regulator was stainless steel shiny chrome and one was satin brushed chrome(a bit duller) which is less likely to get scratched, dinged nicked etc easier? which will look newer longer? Ive got a chrome one and only 15 dives seems like its staring not to look new anymore . (maybe boat guys in Philippines a little rough on it) My next purchase will take it into consideration. is ti same brass under both?
The body is always brass. Chrome looks nice when new but it definitely scratches quickly and loses it's luster.
That's one reason that I'm a fan of the newer Cycolac (plastic) bodies. They have a lot of advantages.
Alec
@@AlecPeirceScuba_SeaHunter Ahhh interesting, definitely will take a look, considering one for my next purchase then. Im sure it would be A lot lighter. THUMBS UP !
@@AlecPeirceScuba_SeaHunter I don't think you'd recommend plastic for cave diving?
Alec, you neglected to respond to anything I said?
Thanks for taking your time and explaining their differences. I will purchase my regulator accordingly, I like my equipment simple, simplicity wins.
Glad it was helpful!
The question that wasn't answered is, if both kinds do the same job, why would a manufacturer choose one over the other? In my case, I didn't choose a diaphragm 1st stage, I chose a complete setup (Aqua~Lung Legend LX Supreme) based on the balance between price and features of the 2nd stage, and a diaphragm 1st stage is what came with it. I had no say in the matter.
And that's normally the way it's done Brian.
A diver would not normally go into a dive store and ask for a piston regulator. He would ask for a good regulator or a regulator system. The store would show him what's available, explain the differences and help him pick the best one for his diving needs and budget. And let me make it clear that it really doesn't matter which style one gets. They both work well.
Aqualung has had several piston regulators over the years but the first ones were diaphragm and they sold them for a long time. I don't know if they have any pistons in their line right now but they are comfortable making and selling the diaphragm style so just haven't bothered to change. Most manufacturers offer both (Scubapro, Oceanic, Cressi, Mares, Hollis, etc) while some offer only pistons (Sherwood, Genesis, Atomic, etc). Only Aqualung and Apeks (same company) restrict their line to diaphragms.
At the risk of irritating a lot of divers and dealers, a search of The Best Scuba Regulators often shows several sites that list the top regulators available today and those regs are #1 the Scubapro Mk25 and #2 the Sherwood SR2 both of which are piston style. I have used both, sold both to hundreds of divers and serviced hundreds of them. I can't argue with the their popularity.
Talk again soon.
Alec
You go into great detail it’s good I’m the guy that ask to many questions the reason why is i want to know when stuff goes bad what to do and not be that guy u read in the paper my flight instructors when doing pilots licence said u don’t need to know that I’m like yes I do think worse case
Thanks for posting , the 1st stage have always been a mystery and never serviced mine, but I have serviced my second stage with no problems....
I'll be doing a follow-up on servicing both stages soon.
Take care.
Alec
Hi Alec, I need your opinion if you be so kind. I am looking at snorkeling in 12-15 ft depths, I plan on using a long flexible tube to breath with but am wondering if there is such a low pressure diaphragm mouth regulator i could use so that i can release my oxygen waste instead of recycling when breathing. Can you suggest such a mouth piece that may do the job?
Any input will be greatly appreciated. Many thanks for posting your videos keep them coming!
Sorry to rain on your parade but it simply won't work.
One can not breath underwater through a tube that is longer than about 18".
When I was actively teaching, I'd illustrate this principle by getting the biggest guy in the class to lie on his back in the shallow end of the pool and try to breathe through a tube. I'd stand on his chest which was about 2' down.
It was great fun and a dramatic display to watch him struggle to take a breath and then struggle to get to the surface.
Sometimes I suggested that he use the pool vacuum hose which is about 3" in diameter.
That sure looked easier . NOPE!!
Take a scuba diving course. You'll love it.
Alec
Alec, thanks a lot for all the information you have shared in your fantastic videos! I am a rockie diver and being in the process of acquiring my first pieces of equipment I have found your teachings nothing but invaluable! Keep them coming, I will try to keep learning... I do love how you explain why something is the way it is! Thank you very much indeed all the way from Argentina! Cheers.
You're very welcome Guillermo, all the way from Canada!
You have so much to look forward to - I'm jealous.
Alec
Hey Alec. Thanks for another great tech tip. I understand the benefits of a piston regulator (simplicity, ease of service, lower cost) but I came away from the video wondering what the benefits of a diaphragm regulator were. Can you elaborate more? Thanks again!
I'm sure that USD or Mares would like to see a list of benefits of the diaphragm over the piston but it wouldn't be easy to make such a list without stretching the truth or at least invoking a bit of marketing hype.
I'm not bias in any way. My favorite regulator of all time was the excellent DACOR Pacer 900, a diaphragm. I was trained on an Aqua-Lung Mistral, a diaphragm (terrible breather by today's standards). And my first own regulator was an Aqua-Lung Aquamatic, a diaphragm. But the simple fact is that both types do exactly the same job - supply air at proper pressure to the 2nd stage. And they both do so perfectly well. The piston is just cheaper, has less parts so in theory anyway is more rugged and reliable and it's easier and cheaper to service.
I'll think on that and see if I can a find a genuine benefit to the diaphragm style.
To the diehard diaphragm enthusiasts I offer this - 99% of all 2nd stages are diaphragm.
There. See I'm not biased.
Thanks for watching Dan.
Alec
Wow.... i usd diaphragm poseidon. I always thought that they are the simplest possible
The simplest reg made is the standard piston. It has 2 moving parts - the piston and the spring. Quite frankly, it will work without the spring so really has 1 moving part. Can't get much simpler than 1 moving part!!
Take care.
Alec
Great video, straightforward. No nonsense. Thanks Alec
Thanks Kevin.
Alec
Hi Alec, I’ve been seeing the term “flow by piston” a lot on entry level/rental regulators. What does that mean? And how does it compared to other piston regulator used by high end models made by scubapro or atomic?
If it has a piston, it is a 'piston' first stage. They can add any other words they want but they ALL work on the same principle. Note that 'flow by piston' means the air flows by the piston, which is how its supposed to work. Like saying "gas in a car", it better go in the car, get my point? Thanks for watching.
Hi Alec,
nice video (as always). However, as you said, you hit a controversial topic. I felt you didn't explain the pro's and con's of both pistons and diaphragm 1st stages. I'd really appreciate a second tech tips on this topic, with more details.
As I hinted, both work well. Neither has a big advantage and certainly not in performance.
I may do another tip though to share a couple more points that I left out.
Thanks for watching.
Alec
Excellent video!
Thanks for watching.
Alec
Alec, I need help picking a regulator, so far I know I need DIN because of HP tank and it has to be for cold water use, my previous first regulator was Tusa rs360, yoke. I bought it brand new about 8 years ago. I was looking for Tusa rs790 but its diaghram, I want something more simple, like the piston style. Then I start checking out Scubapro mk25, someone said its oring central, and that I dont remember what part but something is cracked internally from factory sometimes. Then I started to look at Atomic M1 or B2, m1 shows that it's freeze protection standard and B2 is optional on comparison chart. I also like the idea of servicing every 2years or 300dives. Thank you.
The Scubapro MK25 has been around for a very long time. I think you'll find it's one of the most reliable regs on the market. It too has a 2 year service period but you may be able to get free parts and that's worth looking at.
The Atomic is quite good too but service is not so widely available and parts are not cheap.
Alec
Alec Peirce Scuba thank you reply, I ended up getting brand new Hollis DC2/212 DIN for $209 shipped. I was looking at Used atomic m1 and scubapro mk25 and it should have cost me around $350-400, plus around $100 for service. I will be eyes M1 or mk25 for future most likely but they are not cheep. I asked one shop about Abyss pr MK25, they said hands down mk25.
Thank you Mr. Pierce for your wise advices. I have dived for more than 10 years with a Mares 2T Diaphragm Regulator. I want to buy now a Piston Regulator. Please help to decide which Piston regulator do you recommend from these: Sherwood SR2 Balanced n Sealed , Atomic Z2 Balanced n Sealed , Scuba Pro Mk25 Balanced n Not Sealed , Scuba Pro Mk2 Not Balanced n Not Sealed , Aqualung Calypso Not Balanced n Not Sealed , Mares Rover 2S Not Balanced n Not Sealed , Oceanis SP-5 Not Balanced n Not Sealed. Your opinion is extremely important. Thank you and keep your wounderfull work !Sincerely, Jose Manuel Portilla from Acapulco, Mexico.
That's quite a list Jose.
Of course my opinion on what you will like the best is subjective but maybe I can help narrow it down.
The cost of balanced over not balanced is small so a balanced regulator is the way to go.
The Sherwood SR series has many years of solid performance behind it. It is one of the most advanced designs available, offering incredible breathing, simple diver control and inherent environmental protection. And Sherwood is a very large, international company with distributors and dealers everywhere. Sherwood is often the choice of training and rental organization and commercial divers because of its proven reliability.
Atomic makes an excellent product. I have two concerns with Atomic. It is a small company so service and parts may not be available whenever or wherever you need it. And it's environmental protection is a pretty standard add-on designed to stop water from getting in rather than a feature of its design as with the Sherwood regulators. Atomic does a great job of promoting it's regulators as unique and "unmatched" in the scuba world but neither is true. Their cone-shaped HP seat is not the first such design and to claim it is the "most reliable in the industry" is unwarranted hype.
So, it comes down to your personal decision as to which you like and which will ensure easy access to service in your dive plans.
Either will do a great job for many years.
I hope this helps.
Alec
He is correct, 3 piece is cheaper then 12 pieces, unless it's made out of titanium or like metals.
Price isn't the only motivation, nor even the most important. Reliability and ease of service must be considered.
Alec
Hey alec, been diving for 2 years now and planing to get my own set of regulators and I’m looking at edge compact pro reason being it’s value for money
Any opinions on it ?
Appreciated sir
I don't make individual recommendations Jonathan as I'm not here to sell anything but to educate and entertain. For guidance, watch my video S05E09 $300 vs $800 regulators to see what the key differences are. It may help you decide what to buy based on your diving style not what looks nice. Thanks for watching.
Does one or the other work better at depth. I have a Dacor viper tec just rebuilt diaphragm reg and years ago when it was new I dove to 80ft and remembered how hard it became to breathe. I've had it rebuild before parts are gone by Brian at Lake Hickory Scuba but could never get an answer why it was so hard to breathe at depth past 60ft. At first he thought it was a piston and that's why but it's a diaphragm. 2nd stage is dacor viper tec as well. Any thoughts?
The question is was it a balanced or unbalanced diaphragm? Balanced should breathe almost the same at a reasonable depth, wether it is piston or diaphragm, if it is unbalanced the work of breathing will increase the deeper that you go. It should not be that bad at 80 feet, it sounds like it was not properly adjusted.
Love the tips, only just found your channel, will certainly watch more. A Brit!
Welcome aboard!
Balanced piston regulators vs piston regulators; can you explain the difference? I know balanced = good when tank pressure is lower
I may do another one about that since there are a lot of misunderstandings. I'm always shocked by the lack of knowledge among dive store staff and amazed at some of the explanations I hear. It's small wonder divers are confused.
Thanks.
Alec
Thanks again Alec. Always like your objective views on tech tips. I tend to agree that less is more - a bit like many things these days; if the basics are done well, who needs to over complicate the process!
I have learned from personal experience and from watching hundreds of other divers struggle with gear that simple is good.
But it's fun to have toys too. So long as your basic gear, your breathing stuff is simple and reliable, that's good.
Thanks for your comment Ed.
Alec
Instablaster.
Alec,
Thank you so much for you awesome vids! I recently purchased an Atomic B2 regulator. Two questions for you:
1) It comes from the factory with the secondary hose already attached to the "in line" LP. I've read that this provides the "optimal" air flow? Should I leave it where it is or place it in a more traditional configuration and If I did change the location would I lose air flow. Additionally, I'm assuming in the current configuration that the second stage hose should be facing down?
2) Your opinion on the B2 regulator. I'm new diver and my biggest desire in a regulator is the ease of breathing. I'm still a little nervous when I'm diving and seem to be taking BIG breaths. Although, I understand that with time in the water will come more confidence and ease of breathing. But, in the mean time... This specific regulator has received some excellent reviews regarding breath ability. Beside your opinion on the B2, could you recommend a few regulators. Thanks in advance.
The Atomic B2 is an excellent regulator.
Relax. It is NOT all that unique.
Atomic has done a wonderful job on their website and literature to explain how their regulators are the best of the best.
In fact, they are among the best. But, everything they claim to be unique and special is actually quite common among all top end regulators. They have been particularly good at making up names for the "special" features. Other companies have not done that but they have the same features.
This is not a knock against Atomic. It's just trying to point out the difference between marketing and production.
You can put the LP hoses to your primary or secondary second stage, or the BCD inflator for that matter, into any LP port you choose. They all work equally well. Whether a hose points up or down does not affect performance. You should choose the configuration that works for you and is also recognized by other divers so they can assist you or you can assist them without having to check the instructions.
As you get more experience you will begin to relax and your breathing will become more normal. With time you won't ever notice your breathing. On 2 separate occasions while scuba diving I fell asleep underwater. To say I was relaxed would be an understatement. It was only a problem on 1 occasion - the reg fell out of my mouth!!
Take care. Enjoy yourself. Don't get too caught up in the technical aspects.
Alec
Alec,
Thank you for such a quick response. I truly value your opinion over other people. You present facts and let the consumer decide what fits their needs. It can be overwhelming walking into a SCUBA shop and trying to decide what to buy. They all have their biases towards certain gear and tend to only promote what is best for them, not the consumer.
Thanks again.
Have great Memorial Day weekend.
Thanks a lot :) Now, of course i prefer simplicity :)
Glad it helped!
I noticed the piston regulator shown is unbalanced and the diaphragm regulator is balanced. Is the a part difference between balanced/unbalanced of the same type?
hi, what do you think about the Atomic Aquatics T3 Regulator
Atomics regs are well made and give great service.
Be sure you have a good source of service for them.
Take care.
Alec
Thanks for another great intro level video. I am a bit of a gearhead so I purchased a near new and serviced ScubaPro Mk25 / S600 combo a month ago because of the excellent performance and reliability reviews. Probably more performance than I'll ever need, but the international status of SP will hopefully be beneficial in parts, servicing availability, and resale in South East Asia. The exploded view of the Mk25 shows quite a bit more components compared to the unit you disassembled, which I assume is because of the balanced piston design?
You're right - partly. Scubapro gear is one of the best and you now have one of my favorite modern regulators - the venerable MK25/S600. That MK25 has been around a long time and there have been numerous upgrades and improvements made over the years. It seems that each improvement added a part or two. It's still a pretty simple regulator and if you can look at one in action you would see that it too has only 2 moving parts - the piston and the piston spring, just like the one in the video. Most of the extra parts are static - they don't move and are there to enhance performance. Some increase the sealing surfaces, some soften the piston movement, some are there to make service easier and so on. They don't detract from it's simple reliability.
The fact that it's balanced and so offers better breathing characteristics (note that I did NOT say easier breathing!) doesn't really add to it's complexity. Balancing a piston reg only alters the path of the air flow. The piston still just moves up and down.
There are pictures of the MK25 showing the air flow on the internet. See if you can find them.
You've got yourself a good one!
Take care.
Alec
Yes I was able to find this cut-away view and operational video of a simple piston first stage here: th-cam.com/video/cq2yRQDwEKM/w-d-xo.html. Informative albeit in French, thanks for the tip!
french canadian version of 'how it's made' US show.
Hi I enjoy your videos , very informative . Do you have any suggestions on getting certified as a repair tech . Thank you.
Suggest starting with a certification from a manufacturer, ie Sherwood/Apexs etc., to see if you really want to invest the time and money into it as a hobby or full time. Visit your local dive shop and ask them about equipment courses or ask to watch your regulator be serviced. If they know your thinking of becoming a service tech technician, they may let you watch or help find a course to get started. Be careful of over investing time and money if it won't pay you back or is too stressful.
Hope this gets you started Frank.
Alec
thanks Alec, great information, keep videos coming
More to come!
Thanks for the video. I didn't know! Always assumed piston were the old school first stage, and that in order to get a balanced regulator (as easy to breath at depth or when running low on pressure) you needed a diaphragm first stage (what I have now) ? When I started diving in the late 70s you could tell you were running low on pressure well before as it became harder to breath, same at greater depth. Is it possible to avoid that with a simple spring+piston ? the spring tension is fix, so as the air pressure goes down you get less air flow wouldn't you ? also environmental seal with diaphragm, wouldn't you get less corrosion as you don't have salt water enter the spring chamber ?
In theory you can detect low air pressure from the increased breathing effort in any standard (unbalanced) regulator whether diaphragm or piston (maybe a bit more with piston for technical reasons that would require an entire new website to discuss adequately).
However, either I'm not very sensitive (as all my wives have claimed) or I was always so in to the diving that I failed to notice, I've never really noticed such a change.
Corrosion is an issue both without and with anti-freeze kit (sometimes called erroneously and All Environment Kit (AER for DACOR in the 70's). It can be even worse with a kit installed if it's not checked regularly. See my reply to wbatten1 below.
However, in theory again, it's should be less of a problem with a kit installed.
Thanks again Alain.
Alec
Alec, with water entering the spring and piston chamber wouldn't a simple piston design corrode much easier than one that uses a rubber diaphragm to push a piston instead ? even in your video you see your spring and rode quite corroded (didn't slide or separate out easily). Does it mean a diaphragm reg doesn't need anywhere near the same amount of servicing, even if more pricey ? reminds me of my BMW requiring oil change every 15k miles vs my Acura every 5-6k. Cost more (synthetic, more quarts, etc..) but much rather do it myself less often :)
Great video again. Hope next video will be soon :)
Should be every week now.
Thanks for watching.
Alec
Hey Alec.. can you tell me how to know if a 1st stage regulator .. like a Dacor 460 is a plunger or diaphragm regulator? I looked in the LP ports, all I see in the 460 is a small shaft that makes me think it's a diaphragm.
My other regulator, had a thick spring when I looked in the ports. I'm not sure but it may be a sherwood that I traded something for and never needed it till last month when I bought new 2nd stages for both of my regulators.
If plunger means piston, then the Dacor 460 is a piston model. First year of manufacture was 1989 and still a easy to use reg. Watch this video to see how to identify piston vs diagram regs S09E22 by sight.
Dacor models 300, 350 and 360 are diaphragm's and 460, 600 and 760 are piston. Finally the 900, 950 and 960 are diaphragm's.
@@AlecPeirceScuba_SeaHunter kewl thanks. I believe as soon as I get some new hoses or a set of adaptors, that this will be my primary dive regulator. The other two will become back up or the "loaner regulators". lol.
Sorry about plunger thing. I typed "piston" but for some unknown reason spell check kept changing it to "plunger"!
We called them: balanced first stage and unbalanced first stage. Some show the difference if the divers dive deep and breath heavily.
There are a several factors in play before a diver really notices harder breathing with an unbalanced: depth, inhalation force, is a venturi assist on the 2nd stage, diver fitness, tank pressure. I dove unbalance 1st and 2nd stages for many years, could not afford balanced ones, and when I did convert over, did not notice much. It's not like going from standard definition TV to 4K, but some may notice it late in a dive.
@@AlecPeirceScuba_SeaHunter was wondering as well when people say it good to have balanced regulator (trying a few balanced and overbalanced).. still dont think worth to have it tho. since the unbalanced just do the same. But of course if does feeel surreal to breath in with those balanced regulator (where u can inhale all the air by adjusting the knob of venturi (VIVA) to reduce flow resistance.
For regular spearfishing weekly 4 to 5 times
What kind of regulator is good
Is good to be 2 hp output n 4 low pressure out put
Piston or digraph
Bal or un balnce
Din or York or din adoptor buy separately
Do bcd will play major role in spearfishing n how about dive computer to buy
Please share ur wealthy knowledge for us so that i can make nice move before buying all diving stuff thanks alec
If any things I miss please suggest me
For me safety is first not price
Which cylinders will be better 80 cubic feet or more
Lots of questions Caji so let me quickly start. First buy the best reg your can afford. Sounds silly but if you only have $300 then that is what you can buy. Check out my video S06E01. The rest of your questions depend on location really. If in North America, then its yoke, 80 cu/ft tank, otherwise its DIN and 12L. Remember its also the speargun and practice as scuba gear gets to near the fish, you have to spear it next. Good luck and thanks for watching.
Din regulator and yoke adapter will let you dive any tanks, anywhere.
It’s nice to watch your videos with the 0.75 x playback speed :)). I totally understand all with the normal speed as well, but as a foreigner sometimes it’s too tiring to focus your words for long periods 😁
Interesting! I do talk a little fast but thanks for watching.
Alec Peirce Scuba thanks for the great videos! I’m a subscriber to your channel since long time back
Less moving parts, less to break and wear out. Just like a Glock pistol.
Ok.
The principle is sound.
Alec
if piston is better than diaphragm why did the scubapro people make the mk11 and mk 17 for the longest time they are the one insisting that piston are better than diaphragm
The Scubapro Mark 25 is regarded as one of the best regulators of all time - a piston. Scubapro, since you picked it, has had many more piston regs in their line up than diaphragms.
Their MK 11 and Mk 17 are both fine regs but not nearly so popular as the 25.
I suppose the answer to your question is that every company wants to please every customer. Some divers want to buy a diaphragm regulator so Scubapro feels compelled to have one or two in their lineup.
Sherwood, a major brand name for many, many years, has never offered a diaphragm reg. Their reputation was built on rugged reliability and easy maintenance.
US Divers (Aqualung) like Scubapro, has both in their reg line. They tend to lean toward diaphragm regs at the moment but have had several quite famous pistons over the years - the Calypso, the Aquarius, etc.
I don't think I've said that a piston reg is 'better'. I favor a piston reg because of its reliability, simplicity, cost and ease of service.
Both designs do the same job. The choice, other than the factors I've mentioned, is really personal.
If one was not as good or as safe as the other, it would be gone.
Take care.
Alec
Piston reg just as with a double hose reg! Simpler is btr! Fact!
Too often the "Newer, Better, Improved" version is simpler more complicated. Manufacturers will add features that are of no benefit whatsoever other than to increase sales to unsuspecting divers. This doesn't just apply to scuba gear of course. Think about automobiles which change every year for no good reason so that your new car from last year is now obsolete. What an incredibly stupid system. Or cell phones. Is the S8 really better than the S7?
Thanks for watching.
Alec
Alec Peirce Scuba Ya Alex all the phones are the same! Fact! And all this new scuba gear is ridiculous! And I will stick w/ 91 f150 Lariat XLT.😀
Thank you for the information. It’s very useful. How about balanced vs unbalanced?
Easy, watch S09E22 Balanced Regulators - Why/How?
@@AlecPeirceScuba_SeaHunter Thanks once again for the other video that you showed me. In that video, you mentioned a diaphragm (as opposed to a piston) in both cases (balanced and unbalanced). That leads me to another question: do piston regulators also come in two varieties, balanced and unbalanced?
I liked your explanation. Thanks
Thanks for watching Pez.
Alec
Great explonation video! Thank u!
Glad you enjoyed it!
A
balanced first stage or not?!
how deep do i need to go before there is a use of a balanced one?
in meters.
// Jony @ Sweden
You can dive to any safe depth with a standard (non-balanced) regulator with no problem. They work just fine. I've used them at 100' (30M) and more lots of times and the water is cold up here at that depth. When I started diving there were no balanced regs.
As I mentioned in the vid, a balanced reg is not BETTER. It does give more consistent breathing and will supply larger volumes at deeper depths but they are no safer in a normal dive.
Alec
Tanx!
Keep making your amazing videos, I've just started taking my Padi ow cert, and your tips help me to save money in the right places.
//Jony @ Sweden
love the videos. I am curious, I know the purpose of a balanced first stage, but how does it work exactly? are there different parts in a balanced first stage than in an unbalanced?
Surprisingly, a balanced piston regulator is almost indistinguishable from a standard (non-balanced) regulator. Particularly in a piston regulator, it's the easiest thing in the world to balance it and doesn't even require any additional parts. In fact, there's 1 less part!!!
BTW, NO! You can't do it yourself!
Balancing a regulator is a mysterious concept that baffles most non-technical people - and I'm NOT referring to technical meaning technical divers. I mean technical as in a mechanical engineer.
Scuba manufacturers and scuba store staff use this mystery to their advantage when selling gear and will tout the advantages of a balanced regulator to upsell a diver knowing that the diver probably has less understanding than themselves!
I'm not saying that a balanced regulator is not worthwhile. I AM saying that it is not necessary for most divers despite most scuba store staff leaving you with the impression that you are playing with your life if you don't buy a balanced regulator.
I'm going to make a video on Balanced vs Non-Balanced regulators to show how it works but I can give you a quick, easy description.
Picture a tin can, maybe a soup can, that has a small hole in one end only. Into that hole insert a rod that is a tight fit, tight enough to seal a bit but not so tight that it won't slide in and out. You can fairly easily slide the rod into the can and pull it out of the can. Now if you increase the air pressure inside the can, it will tend to push the rod out of the can. Now it's much easier to pull the rod out of the can and much harder to push it back into the can. You will see the same affect in reverse if you increase the air pressure outside the can (or decrease the pressure inside). The rod is easy to push into the can and harder to pull out. That's how pressure changes affect a non-balanced regulator.
Now punch a hole in both ends of the can and put the rod right through the can so that it sticks out on each end. The rod will slide back and forth through the can fairly easily again. And, magically, if you increase or decrease the pressure inside the can, it has no affect on the effort needed to move the rod!
In a balanced regulator, the piston (in this case) will move as designed with no change in effort regardless of pressure changes inside or out.
I hope this is clear and helps your understanding.
Watch for my video - "Balanced Reg or Unbalanced - What's the Diff?"
Take care.
Alec
Thanks much sir. I’m Tim from Knoxville TN, btw. Again love the vids
better explanation than the video which mentions the feature and benefit but not how it works...
Don’t u mean piston regulator for the second one
Probably. These are completely unscripted.
Sometime my brain can't keep up with my mouth.
Thanks for watching.
Alec
Alec - I have the Diaphragm model that you showed in this video (Zeagle Envoy). I have had it for about 2.5 years and have 117 dives on it. Zeagle calls for it to be inspected annually, but does not have a schedule for a rebuild. What are your thoughts on when this regulator should be rebuilt?
Well, 117 dives is a lot! If you've not had it serviced, now's the time.
Generally it's suggested that a reg system should be serviced every year or 25 dives. Most reg manufacturers are now suggesting every 2 years.
The problem is that there are many factors other than time and/or number of dives. For example, if all your diving is in fresh water, every 50 dives is a good number to use. If you carefully rinse your regulator after every dive, dry it and store it sealed in a ZipLoc, maybe every 75 dives would do.
At the opposite end are regs that are used daily (rentals or training) and are not cared for well. We used to check our training or rental regs every week and probably 1/2 of them required some service.
Now comes the question of service versus rebuild. Quite frankly, while some dive shops will rebuild a regulator at every service (Why not? They make a lot more money!), a rebuild is necessary only if the reg demonstrates signs that it is not functioning perfectly. If the IP climbs, if the breathing effort is high, if it freeflows, if it looks abused and so on, the serviceman should rebuild the reg. It's tough to pin down the exact cause of some problems and they are often related to each other. Best to simply rebuild with a complete service kit than try to fix it by replacing 1 part or 2.
So once the warranty period is over (if you even care about that), you need to make an informed decision as to when to take your reg for service and to tell the serviceman of any problems if they exist.
Good luck.
Alec
Alec - Thanks for you advise. I take very good care of my equipment. Always rinse in fresh water. Most of it looks like brand new... on the outside at least. One more question: My regulator is a Zeagle. Do you think I should seek out a Zeagle dealer, or would any SCUBA Tech be able to competently do the job?. There is a local guy here in Myrtle Beach that caries mostly Aqualung. He said he can service any brand....
Alec, thanks for your answer. Even my reg was stored 25 years, it still looks like when I put it away, IP haven't changed and works perfect (in pools). Don't worry, befor I go diving in a lake again, I'll do a service 😊
is it normal to hear a noise similar to "inflating a baloon" using an unbalanced piston first stage? (mares r2)
Generally and 'noise' coming from a 1st stage means service is needed. In piston regs when the O-rings are worn, high pressure air is leaking past the o-ring causing high pitched sounds like balloons. If this sound is not heard when new, then a service checkup may be needed Alberto.
@@AlecPeirceScuba_SeaHunter thank you very much! I will make it check. By the way the noise is not high pitched.. it is like if you're inflating a "party" baloon, so basically an "air flowing" noise you could hear from your mouth to the baloon (I have no better comparison ahahah). This I a spare reg I have (very different from the reg I normally use which is scubapro mk10), and probably the noise was always there and I just didn't realize.
Anyway Thanks a lot! Keep up your good work, as always!
not more reliable
Is there any difference in operation if the ambient pressure is greater than the intermediate pressure?
In theory that can never happen. The regulator is always subject to ambient pressure and that pressure, regardless of its source or intensity, is added to the IP. Thus, if the ambient pressure at the surface is 15psi (1BAR) and the IP is set at 150psi (10BAR), at 33' (10m) where the ambient pressure is 30psi (2BAR), the IP is now 165psi (12BAR), and so on.
If the ambient pressure is greater than the IP, the regulator is broken!!
If you are thinking about what happens when the ambient pressure exceeds the IP such as at 330' (100m) where the ambient pressure is 150psi (10BAR), the IP would now be 300psi (20BAR).
Take care.
Alec
Alec Peirce Scuba Thanks very much. A nice clear and concise answer.
Great information. Thanks!
Glad it was helpful!
Great video love this guy he is quirky
Quirky?
Could be worse. Thanks for watching Josh.
Alec
Please come open a dive shop in Indianapolis.
Thanks K B but I have owned many, many dive shops in the USA, Caribbean and Canada over my 50 years in the business. I like retirement too much to start up in lovely Indianapolis.
Alec
this is great info keep it coming Alec
Thanks.
Alec
Hahahahahahahahaha poor Kevin!
Totally agree and Kevin reads all the comments too!
I love being poor, I leave the money to you
As the saying goes, you can be rich or a scuba diver, not both!
Piston: Simpler in design? Yes. More reliable / durable / rugged? Absolutely not. Nearly all studies performed on the two designs show them to be about equal. And that only holds true if the piston reg has been environmentally sealed in some fashion- otherwise, diaphragm wins (excluding abnormal events, such as multiple flooding of the regulators.) Cheaper? Again, no. They are very comparable. In fact, when calculating the cost of maintenance of high-end Piston vs Diaphragm regs, I would argue that a diaphragm is MUCH cheaper, let alone the initial cost being cheaper.
So where does the piston regulator really win? Besides a simpler design, they theoretically offer higher potential air flow. Does the higher air flow matter to the consumer? Nope- not unless they plan on having several divers breathing off of one 1st stage at extreme depths, or 20+ divers breathing off one 1st stage at recreational depths.
This really isn't up for debate either. Unfortunately, too many myths float around as truths. Some of you may ask, what makes me the subject expert on regulator design; to which I respond, it's my job.
Also, technically there are two piston designs... I believe Sherwood is the only major company that uses the other though.
I really appreciate your input and accept it as your expert advice W.
I will suggest however a couple of things based on 47 years as a scuba regulator serviceman.
1. a piston reg is much cheaper to service and for good reasons:
a. it takes about 20 minutes to completely clean, overhaul and set up a piston reg as compare to about 1 hour for a diaphragm.
If a dive store charges a flat fee to service a reg, the charge will be the same but that's patently unfair. It ought to be cheaper
for the labor on a piston. The service involves simple removal of the cap, changing 2 O-Rings, replacing the HP seat and filter
plus any cleaning of course.- Done!
b. a 1st service kit includes 2 O-Rings, 1 HP seat, 1 filter. Piston kits typically cost less than $20 (even that's overpriced!).
Diaphragm kits include many more parts and generally cost closer to $75.
2. there is no difference in the anti-freezing abilities of the 2 styles assuming neither has special environmental options.
The diaphragm reg will have water against the rubber diaphragm while the piston will have water against the stainless steel
piston stem. Neither of these parts is related to the freezing problem The freezing problem occurs at the HP seat-orifice
junction which is located in a similar position in both regs - well away from any water. Even with anti-freezing options, the only
advantage for both is that no water hits either the rubber diaphragm or the piston stem. I admit that, once freezing begins, the
piston regulator will react more quickly, in an unfavorable way. But the design did not facilitate the frezzing.
Now if you consider the Sherwood piston regulators that use a Dry Air Bleed anti-freeze design, unique to Sherwood, no water
enters the body of the regulator at all. Plus this design does not need any anti-freeze liquid (alcohol or silicon oil).
I've never been a big fan of the anti-freeze liquid design as used on most diaphragm regs and on some pistons too. These are
the kits used on Aqua-Lung, Mares, Apeks, and others. They can be recognized by the flexible (rubber or silicon) cap on the
adjustment end of the regulator.There's good reason for that too:
a. they are messy as heck and make service a nightmare.
b. the anti-freeze kit is costly, typically close to $100.
c. annual service is more costly for both labor and liquid replacement.
d. liquid sealed diaphragms are slightly but measurably less sensitive to outside pressure changes. And if any air is trapped
under the anti-freeze cap (resulting from poor service methods), compression of that air makes them even less sensitive.
e. unless the cap and liquid are checked on a regular basis, any tiny leak in the system will result in slow mixing of the anti-
freeze solution and water. The resulting corrosion from the trapped water can be disastrous. I have seen this many times.
You are completely correct on the piston regulator offering greater air flow (assuming a balanced regulator of course). The reason BTW is that the HP orifice can be larger on a piston style. Theoretically it could be even larger but size restraints on the overall size of the 1st stage limit the size of the reg and as you say, there's no need for that much air flow for scuba divers.
However, a larger orifice and the resulting greater air flow has more value that just the ability to deliver more air. With respect to the anti-freeze ability of the reg, a larger orifice has a lower likelihood of being affected by ice from adiabatic temperature drop - the real reason for reg freeze-up.
I won't question your credentials W but I think some of your deductions are not well thought out. A simple check on-line of the cost of piston regs vs diaphragm will show that a simple piston is cheaper than a simple diaphragm. It is BTW just one reason why the rental departments of most dive stores use piston regulators (unless as is common, they are swayed by the dealer commitments). Other reasons are the aforementioned cheaper parts and shorter, easier service times.
And similarly, it's easy to compare on-line the cost of a piston service kit to that of a diaphragm service kit and again the piston is generally cheaper.
It may not be good for us to chat up a reg design because "it's cheaper" but for the purpose of this conversation, it's appropriate.
You mention stats or studies comparing the 2 designs. I keep pretty current on such things and have regular conversations (often lengthy) with several recognized scuba regulator experts (Global technicians, DCIEM, etc) and I don't believe I've ever seen such a study. I'd love to look at it. Please provide with us with a link if possible.
In the meantime, thank again for watching and for your input.
Alec
1. I'm not sure where you get 20 minutes vs 1 hour- at least not on modern regulator designs. BTW- I envy the history of gear you have... Truly amazing. (Side note- Any chance you'll be selling some of those home-built setups you have? :D)
A modern diaphragm vs piston are rather close in terms of service time. The time required to remove the HP and LP port plugs / hoses is about equal to disassembly time. Cleaning takes the longest, and the use of an ultrasonic cleaner makes it a moot point. Assembly on a diaphragm takes a bit longer, but not more than 2-3 minutes more. Adjusting a diaphragm takes much less time as you don't have to disassemble to add or remove shims- you just turn the adjustment screw.
I'm ill versed with Mares regulators. However, nearly all modern diaphragm enviromental seals use dry systems- no oils / grease needed. This includes Aqua-Lung, Apeks, Dive Rite, HOG, Deep 6, Hollis, Oceanic, and many others. Also, there's virtually no additional cost for environmentally sealed diaphragms nowadays because of the dry design. Environmentally sealing piston regulators normally require the use of a LOT of christolube or something similar, which gets extremely messy, costly, and very time consuming to ensure no air pockets exist.
I know pricing in Canada is different than in the US. Though dealer pricing for most diaphragm service kits in the US is much lower than what you quoted. In fact, consumers can get Hollis service kits online for about $20. Same for HOG, Deep 6, and several other brands. Most piston kits are cheaper by about $5 to consumers. Also, pistons have a tendancy to need replacement after a few services which raises the service cost. And, to my knowledge, there are no piston regulators that are serviceable at the consumer level (while leaving the warranty intact), except for Countries and municipalities that require it by law.
2. I agree. That said, environmentally sealing a diaphragm is much easier than sealing a piston. (As a random point, you'll only find unbalanced piston regs nowadays) It's also a lot cheaper- see above. (Sherwood excluded, of course.... gotta give you that one.) Again, modern diaphragms no longer use that horrible oil design. Folks still diving that type should consider buying new (or converting, if possible) as it will pay for itself very quickly.
On the flip side, the cost of environmentally sealing a piston is time consuming, messy, and costly (excluding using hacks, like a condom or something.) Sure, designs are out there to minimize freezing, like with the SP Evo series... but I think we can both agree environmentally sealing is the way to go.
3. I believe Scuba Pro holds the "World Record" for most people breathing off of one regulator... it was a piston. I think it was around 130 people?? Absolutely insane! But yeah, I agree- there's no need for that.
4. I'd argue most dive stores use whatever brand they carry for their rental gear, not just anything. As such, piston v diaphragm rentals is solely dependent on what their respective brands offer.
You can contact WMD, ODS, and Aquatec- I'm sure they'll share whatever research they have. You can also try Atomic's plant, but since they only create piston regs, any data they have may be self serving... Also, DAN is a great source, as is the rubicon foundation. One study analyzed the first 1000 incidents from the "Diving Incident Monitoring Study" (DIMS) which started circa 1988. Of those 1000 incidents, less than 10 were from 1st stage failure. Of those, some were from improperly being attached to the cylinder. Very few were from what you and I would consider actual 1st stage failures. Unfortunately, no data exists showing whether the reg was a diaphragm or piston design. Regardless, with less than a handful of failures out of what can be assumed to be tens, if not hundreds of thousands of dives, I'd say my point of reliability holds true. (Can you point to a scholarly, peer-reviewed study that supports your claim?) You're welcome to dig through the first 1000 incidents to see the actual numbers yourself... (I'm not trying to be snarky here- I just don't see a good way to lay it out in a neat way) Here's the abbreviated study (minus the full incident reports):
archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/7762/SPUMS_V33N1_9.pdf?sequence=1
There's also random references, such as in this article, but I don't put much weight on stuff like this since there's no way to view the statistics referenced: books.google.com/books?id=lAFaI9OBlRAC&pg=PA75&lpg=PA75&dq=reliability+of+piston+vs+diaphragm+regulators&source=bl&ots=OqG2WBvqnK&sig=kN1xDn68LnkHloSDwXHpGBdKPrg&hl=en&sa=X&ved=0ahUKEwiY3P_T-8HZAhXnguAKHemlBkc4ChDoAQg1MAI#v=onepage&q&f=false
and, thank you for taking the time to respond to my first statement. Very appreciated - it shows your true colors as a person who cares about the people in our sport!
Awesome thank you.
Thanks Augie.
Alec
Piston for me keep it simple
The piston is well-known for rugged reliability.
I'm with you - reliability is job one!!
Many divers tout ease of breathing but I want air every time I breathe.
Alec
FANTASTIC VIDEO
I'm glad you liked it Gino.
Thanks for watching.
Alec
Good job ,Sir ..
So nice of you
Thank You !
You're welcome!
Excellent!
Thank you! Cheers!
many thanks
Thanks for watching Mark.
Alec
Which one malfunction more
There's no real evidence available to answer that question Curtis. Both are incredibly reliable.
Given the rugged parts and simplicity of design, I would guess the piston might have a slight edge in reliability but I have nothing to base that on other than my mechanical experience.
Alec
Think simply, a diaphragm flexes and a piston literally moves with 2 O-rings that require silicone lubricant! Diaphragms will work indefinitely and without maintenance. You CAN blow one out...but you'd have to back-off the adjustment with pressure on it!
Alec, you missed a few major drawbacks of the piston 1st stage...it requires more maintenance, as in, lube the piston O-rings. The diaphragm does move but it's only a small flex...simpler. Pistons can get contaminated with grit easier. It isn't as adjustable as a diaphragm 1st stage. It's easier to adjust a diaphragm if you don't have an externally adjustable 2nd stage.
I think you lost your footing to the basics in air delivery.
ALWAYS buy the cheapest equipment possible and always piston regulator, of course, NEVER diaphragm. Buy used, overhaul it at home. You can do it. Be sure to have at least one diving knife for all those dangerous situations. Use Aqua Velva cologne.
What? Not Old Spice!
nice vid, but I do still prefer Diaphragm over piston, have you ever seen a Diaphragm reg first stage loosing air , me not, but I have seen a lot of piston 1st stages blowing from the piston O-ring, so simpler is better is arguable.
If simpler was better, why are we not using two sticks to make fire instead of a Zippo lighter ?
2 sticks take too long!! Keep in mind that 2 sticks never breakdown - Zippos always.
Actually, I have seen many diaphragm 1st stages leaking. However, properly maintained, neither style is more or less subject to breakdown.
It's entirely a personal preference. My preference for pistons may be influenced by the servicing of thousands of regs over many years - not because it's a better performer.
This video is not to change your mind but to make you think. Apparently, it worked in that respect.
Thanks for watching Theo.
Alec