What Is An Overpressure Valve? - Scuba Tech Tips: S10E19
ฝัง
- เผยแพร่เมื่อ 1 ต.ค. 2024
- Did you know 1st stages have a built-in overpressure valve. Alec shows how these small but important devices work to protect low pressure hoses from bursting.
Watch my "Alec Peirce at the Ranch" for ranch and home ideas. / @alecpeirceattheranch
**** Alec Peirce Scuba ****
SCUBA TECH TIPS playlists
▶︎ Series 10: • Scuba Tech Tips - Seri...
▶︎ Series 9: • Scuba Tech Tips - Seri...
▶︎ Series 8: • Scuba Tech Tips - Seri...
▶︎ Series 7: • Scuba Tech Tips - Seri...
▶︎ Series 6: • Scuba Tech Tips - Seri...
▶︎ Series 5: • Scuba Tech Tips - Seri...
▶︎ Series 4: • Scuba Tech Tips - Seri...
▶︎ Series 1, 2 & 3: • Scuba Tech Tips - Seri...
VINTAGE SCUBA playlists
▶︎ Series 9: • Vintage Scuba - Series 9
▶︎ Series 8: • Vintage Scuba - Series 8
▶︎ Series 7: • Vintage Scuba - Series 7
▶︎ Series 6: • Vintage Scuba - Series 6
▶︎ Series 5: • Vintage Scuba - Series 5
▶︎ Series 4: • Vintage Scuba - Series 4
▶︎ Series 3: • Vintage Scuba - Series 3
▶︎ Series 2: • Vintage Scuba - Series 2
▶︎ Series 1: • Vintage Scuba - Series 1
SEA HUNT REMEMBERED playlists
▶︎ Series 3: • Sea Hunt Remembered - ...
▶︎ Series 2: • Sea Hunt Remembered - ...
▶︎ Series 1: • Sea Hunt Remembered - ...
SEA HUNT COLLECTOR
▶︎ Website: seahuntcollecto...
The really "pro" divers who use poseidons have this in the first stage since 60 years ago as standard ..... just trolling now :). But this feature of my poseidons is one of those that make me use poseidons instead of other "big" brands. And you need one mandatory for a argon. :) And yes the modern are downstream but the best for cold and deep remain the upstream. Much safer when venting pressure from first stage instead of having that freeflow.
Some of the 'older' gear is just as advanced as some of today's models other than looks and chrome. We all love chrome, right? Thanks for watching.
Alec
Being a 63 year old engineer , got interested in how a regulator works after seeing a Cousteau biography film last week . I searched in TH-cam and came across your Tech tips !!! ... You are such an amazing instructor , so experienced and make your vids so interesting that now i'm hooked on them !!! ... I did some snorkelling as a teenager ( even had a speargun ) ... Now even though i've got cancer i intend to do some Scuba diving before i go !!!
Glad you like these Lou. Look back in my Scuba Tech Tips for more on the inner workings of regulators. Should find interesting points when we can all get back into the water.
Alec
Hi Alec. The other use for these might be if you dive with really old vintage second stages that use a tilt type seat, these will lock up and give you no air if the IP rises. You could have mentioned the over pressure valves on all tanks too.take care Owen m
I'm going to do a video on Burst Disks hopefully this year to cover that over-pressure device.
Alec
Hi Alec, in this time of total lockdown I think your tech tips are going to be a real life line - keep up the great work.
Thanks Peter. Don't know if I will be able to shoot more with the lock down but I'll try.
Alec
Informative video as allways
One additional purpose of OPVs:
If you use an Upstream regulator (there are still a few made today, i.e. Poseidon) you need one but they usually have an OPV built into the 1st stage
Otherwise you couldnt breathe if the IP rises
That was the point I tried to make. Hope you picked up something new.
Alec
Possibly the old cyklons are upstream, but are now downstream. The Jetstream usually has a opv on the connection of the hose and second.
The Nemrod Snark 2 had the opv on the round type 1st.
Some CCRs have the over pressure valve installed. I read having a burst disk on manifolded valves can be a weak point. What's your take on this?
As others have kindly pointed out, I'm not a certified tech or CCR diver, but have done both. Burst disks rarely are the cause of a tank leak where over filling, extreme heat, abuse, no replacement are the primary cause of a burst disk releasing. I think having more than one safety disk, burst or OPV, is enough if you care for the gear properly.
Do you have experience with poseidon? I have a xtream 2nd stage that says ip should be 125psi if my first stage is a scubapro mk11 with a c370 and a ip of 130 to 140 will this be a problem? Thanks
Poseidons are a bit odd. They do require a specific IP and it's usually lower than for many other regs.
So, rather than adjust the Poseidon 2nd stage to work properly with the IP coming from the MK11 1st which is the common adjustment method, you can simply adjust the IP coming from the MK11 to work properly with the Poseidon 2nd.
Assemble the Poseidon 2nd onto the MK11 1st.
Turn on the air slightly. You will probably get a hiss.
Turn the Allen head bolt on the MK11 counterclockwise until the hissing stops.
Turn it clockwise until it hisses again.
Keep doing this back & forth until there is no hissing but it's right at the edge, just about to start.
Breathe. Feel good? Try it in shallow water. Good? You're away!!!
NOTE: this is NOT in the book & may be frowned upon by reg service professionals.
But, it works.
Also note: if you are using a Safe Second, it will have to be adjusted to work at the lower IP otherwise it will be hard to breath.
Alec
@Alec Peirce Scuba so the ip on the scubapro 370 will have to be adjusted from the reg itself dose that take special tools? It seems poseidon needs to use standard ip pressures, and they would sell a lot more in the states because this is the fear most have using. Ed Sorenson from Cave Adventures said I will never notice the performance difference as long as it doesn't free flow. I'll try it in a pool first. A shame they can't be universal 😕 trying to put together my sons first scuba set up, so he will never forget it is getting difficult. I will adjust it like you said 😉
RIP headphone users
Hope not.
Alec
Thx Alex. I been enjoying your videos during this difficult time in Singapore for the COVID-19 quarantine measures. I was hoping the u can do a video on the general tyres & sizes of O-rings involved with scuba diving. I been thinking to have my SAD kit with o-rings or for general service of my equip. Recently an O-ring fly out from the DIN regulator. Fortunately I found it on the boat.
Do stay safe at home..."Live long and prosper" - Spock.
There are only about 3 or 4 O-Rings that a divers needs to have in his 'emergency' kit. By emergency I mean, on the boat just prior to a dive.
A tank valve face O-Ring (if using a yoke), a DIN regulator valve face O-Ring (the one on the threaded insert), and maybe a couple to replace the ends of the hoses at the 1st stage (2 different sizes needed).
Any more than that and you are looking a professional service.
I hope this helps.
Alec
One more of Your superb videos. Always informative.
As stated by others, some 2:nd stages lock up if IP rises.
I have a Divex new from last year that locks up if pressure is not released.
Keep safe and I wait for Your next tech tip.
Regards PeO
Thanks Per. I do have a few left in inventory then have to decide on making any new ones for a while.
Alec
the sad thing is simply scuba has stopped making videos for a while due to the virus. the positive they will be back as soon as they can.
Simply Scuba makes very interesting and informative vids. I'm a fan and watch theirs especially when they talk about us old divers and our 'steam powered' dive computers!
Alec
I look forward to your visit to the uk! Simply scuba is a fantastic dive shop and the guys have helped me with my kit for the last 10 years of my diving. I hope you have a great time here! Welcome to the uk!
Fingers crossed someday we can travel again.
Always enjoy your videos. thanks for the efforts
Thanks for your appreciation. We work hard at it.
Alec
Thank you Mr Peirce for your videos and sharing your knowledge with us
Very glad you like them Ivory. I'll try to keep new ones coming.
Alec
Have you done a video on gradient factors in regards to computers using the Bühlmann algorithm?
No Joe. Most divers are concerned about the features they use each dive. Not the if its a RGBM, VPN, Haldane or others. The subtle model differences between each is not of interest to many. Others, love comparing algorithms as they may affect their personal dive style or profiles.
Alec
Years ago I bought an old first stage for filling tires and stuff. The tech at the store rummaged through his drawer and gave me an overpressure valve and explained its use. People I've shown it to had no idea.
True, look back on my video on "C clips", S09E10, an important part few divers know is inside their 1st stage.
Thanks for watching.
Alec
Hi Alec. As usual I learned something new. Thanks.
Welcome Falcon.
Alec
Does that mean every diver who wears a dry suit, the hose coming from the valve on the tank to the dry suit, they will always have to install an overpressure value?
No. Not necessarily.
Most systems will release excess air, usually through the primary 2nd or safe second.
An OP valve is only required if the likelihood of non-release is possible.
That is, if a problem in the 1st stage occurs and there is no automatic release of the increased pressure, an OP is needed.
A
Hello Alec, We just had the ScubaDillo dive club meeting, virtually tonight. I quite enjoy your videos. I was curious if you would like to do a live talk for us, virtually. We are scheduling more virtual presenters. Especially now. We could do it at a normal meeting. Thank you for your time. Willie - I quite enjoy your videos. Thank you for producing them.
Sure. I'll refer this to Kevin. He's the video tech guy.
Any particular topic in mind or do your members just want to have a question/answer period?
Alec
Kevin just sent you an email to get this started.
Alec
Very nice video! Thank you.
Glad you liked it!
great video...thank you
Thanks for watching.
Alec
Thanks so much for your wonderful vids .
Thanks for watching Lou. Hope you learned or laughed.
Alec
@@AlecPeirceScuba_SeaHunter Both !!!
Another great video and i like the practical demo of adjusting the IP and pushing the 2nd into freeflow! A picture is worth a 1000 words and all that
If i may humbly add a couple of additional points that might make it a sensible descision to add a OPV to a std regulator setup :-)
1) Your demo is with an old unbalanced 2nd. Nothing wrong with these, but a lot of modern 2nds are pneumatically balanced, ie they use the IP to help push the demand valve shut a bit. This means it takes less force to open that valve, meaning they can use a smaller diaphram (for a more compact 2nd) and the diver gets a slightly lower inhilation effort. The side effect however of a balanced 2nd is that the very fact that it is less sensitive to changes in IP (normally a good thing) means that typically it won't get pushed open until a much higher IP. That higher pressure could be above a critical point, either a hose burst (actualy unlikely for good condition hoses as although the working pressure tends to be 250psi, bust pressure is typically >500 psi) or more likely, and potentially just as serious >>>>
2) >>> At some pressure, chances are, the valve controlling the air into your buoyancy control devices (BCD/Wing/Drysuit etc) can get pushed open by the excessive IP! Now you have the potential for a catastrophic ascent rate, leading to potential barotrauma, and DCS, even from fairly shallow recreational depths! Sure, if you know what has occurred, and you react fast,this can be easily mitigated against, by diconnecting your inflators from your buoyancy devices and dumping gas, but it can happen quickly, without warning and potentially when you have hands full doing other things! And as we all know, things snowball so to speak.
3) For most divers a fully freeflowing 2nd stage, especially one being fed with an IP way above normal is a fairly dramatic event! Lots of noise, bubbles, and the feeling that you can't breath because air is being "rammed" into your lungs. Yes, we are all taught how to deal with this event during our training and hopefully we practice these skills now and then, but again, none of us are perfect divers(well 'cept me obvs... ;-)) and things can get out of hand. So for me, the biggest advantage of a completely seperate OPV mounted into a spare port on my 1st stage is simply to provide an external, seperate and more controlled vent for any IP excursion. And because that vent is seperate, and away from my 2nds, even during a pretty catastrophic 1st stage freeflow with IP through the roof, my 2nds breath normally, and my inflators work normally. Sure, i'm thumbing the dive and getting the hell out of dodge, but whilst i do that, i am not tasked loaded by actually having to deal with the problem.
I guess we also should mention the downsides of fitting an OPV.
1) OPV can leak at normal IP's. There are a few types out there, some seem worse than others. The really cheap ones don't have any way of physically "locking" the adjustment screw and these can work loose, undo, and suddenly they leak at normal IP's! DOH! not good, but easily fixed, and easy to spot (do your S-drills / bubble checks everbody!). They also can get jammed open by dirst/grit, but this is fairly incommon because they sit behind the 1st stages filter element. They also can be damaged if gear is dropped and banged into, but again, careful handling of you kit is always recommened. - Carry a spare one in your "save a dive" kit!
2) the OPV is probably mounted behind your head in most cases (for backgas cylinders) and hence isn't that easy to see (eyes in the back of your head???). If it starts to leak, due to a fault with it, you can probably hear it, but not see it. Make sure your buddy knows what it is, and then you can ask them to check it! If it starts to leak due to a genuine IP overpressure, chances are there will be so many bubbles you or your buddy won't be able to tell where they are coming from!
Hope that's interesting to your viewers! Cheers :-)
A very good explanation that should help someone with a OPV problem. Much appreciate the though and effort to share this with everyone Max.