Why Did My Boiler Explode??!! My Own Big Bang Theory...
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- เผยแพร่เมื่อ 17 พ.ย. 2024
- Here’s a mystery for you to solve if you like - why did my flash steam boiler explode?
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It's clear from how the top float's bottom is curved that it had a lot of pressure inside it. Top float exploded, pushing the top against the outlet, sealing off the pressure relief valve (you can see how it's molded against the top of the boiler). Then you got over pressure, and the main boiler leaked from distortion. Thankfully, not exploding. Bottom float had some working pressure relief valve in it, so when it got heated, whatever gas or fuel may have been left in it, got exhausted. Either it imploded when the top one exploded, or it imploded once the system cooled down and it didn't have air enough inside it anymore.
I agree Matthias 💪
Yes
I agree
Yes. There has to be a reason the upper float was driven to pierce itself onto the plumbing at the top of the boiler... with the consequence you describe.
This is What Happened
That 3 mm lid was the ultimate safetyvalve. Can you imagine what could have happened with a 10 mm lid?
they have this crazy chain of safeties in pressure cookers, it's really interesting. On the classic French brand (called "Seb"), old models, the last safety is the lid lifting from the gasket, but the rim orients the flow donwwards to try to reduce the danger radius.
(it was on the older aluminum models, I think the newer stainless steel just key into the lid under pressure, but the safety hardware is made of plastic, I suspect that the last dam is all that plastic hardware popping out for their port under head and pressure)
It would have been safer, because it would allow a predictable release instead of an unpredictable scalding. Good thing his hands or face weren't nearby when it let loose - could have resulted in some nasty burns. The temperature and pressure valve should ideally be the first thing to release, indicating a problem and alleviating it in a controlled manner while you can make a fix or shut it down safely.
@Henkka i think its probaly going to crack a weld on the bottom or top side those small thread diameters are incredibily stong. Doesnt matter if its softer. Surface is the point which matters most
With the evidence shown at this time, I believe that your boiler did NOT explode.
The canisters in side that you had been using s 'floats' to activate the valve at the top may have been the actual explosion with the first one causing the second (I think the top one first) to explode almost instantaneously thereby creating the BANG and enough reverse pressure to bow out the top.
Imploding canisters would make a vacuum that would be filled with steam and water almost immediately creating enough push - much like a tidal wave in the ocean.
The pressure may not have caused the bow but the exploding float bent the lid as it moved upwards. IMPACT damage.
I am nit at all sure of this but it was what came to mind as an issue when you showed us the flimsy canisters going in.
Just glad that you are OK
Steam boiler explosions can be quite spectacular.
This was my theory as well. The top canister did not look imploded, rather impaled on the inlet valve.
Also just a thought, but if it was pressure related shouldn't there be signs of distortion in the metal on the bottom of the boiler as well?
I agree. I've seen an aerosol spray can blow out the side of a house in a house fire I was on years ago. I think the butane tank blew and did the damage not the steam pressure.
Exactly right
Agreed. I remember the boom when mom threw a hair spray can in the burn barrel bag instead of the regular garbage. Quite violent.
@@jerrystott7780 I agree the top float obviously blew its bottom out sending the top up and impaling it on the valve. What ever gas was in the top canister had expanded until it ex🖌ceeded the cans pressure limit. This probably happened as a result of greater temperatures being achieved as you made improvements to the design Tim.
Inspector of pressure vessels and boilers here.
When I saw the boiler construction build (20 min ago) first thing I thought was "how did you get ALL the gas out of the bottle"?
As soon as the top bottle got hot enough to be ruptured, it did. As it expanded the relief valve was either blocked, or simply too small to let all the pressure out and the flat unstayed head (3mm plate) couldn't contain the pressure pulse.
I'M glad you were using a safety relief valve, though I'm not certain you are using a steam rate valve. Just because they are treated for pressure doesn't mean they are reated for steam.
Use a different sourced float (perhaps welded from pipe), and a steam rated safety valve.
With the length of tubing you had in the chimney I don't think you can count it as an open ended system anymore. Besides the length/twists and turns adding up to significant restriction of flow, you could have had liquid condense at some cooler part of the chimney and block it entirely. You could maybe even get a gravity fed backflow of liquid shooting into your chamber right on the edge of boiling again. Not sure about that last bit, but the coils definitely provide resistance. The channel Practical Engineering had a recent video talking about the calculations for flow restriction from various pipe dimensions. I think it was the video "The fluid effects that kill pumps"
But why wouldn't the pressure relief valve have let that overpressure out? My guess is that he is right, and the collapse of the float cans inside triggered a massive sudden decrease, then increase, in pressure. Perhaps backfeeding near-steam water from the exit loop as you suggest. But the point is that only a very sudden increase in pressure could have resulted in the damage, given that the pressure relief valve was still operational after the incident, and yet was not able to release the pressure fast enough. The real question: What makes a better float, or what do you do for water inlet if you don't use that system at all?
@@JamesNewton at this point you can’t determine if the relief was actually venting so there are 2 possible explanations, first it’s possible it was venting but not quickly enough to prevent pressure increasing and bursting the lid, another is that it failed and didn’t vent at all.
Have you also considered that the float collapse may well have resulted in the boiler being completely filled with water and pressurised to mains pressure which was then trying to boil with no vapour space?
I don't think this is the failure mode, although it could be a future hazard. I'm fairly certain that the entire system (with one exception which i'll get to in a moment) was not pressurized above the PORV pressure.
Instead what i believe happened here is the top of the two floats was either not empty, but regardless i think the top float overpressured, rupturing the steel can and dumping quite a lot of pressure into the rest of the system. However, i don't think the top can had butane in it, instead i think it was water.
The valves on those butane cans are made to keep pressure in, not out. so lets say that can gets up to 100 degrees, the butane left in the can pressurizes, but those valves are meant to release that butane safely. it slowly leaks out over a few heating cycles, drawing in a little water with each cycle. More and more water is added with each cycle, increasing the potential pressure inside the can (keep in mind the can that looks like it exploded is on the top, thus is exposed to a higher temperature than the can in the bottom which will sit happily at around 100C) by adding more water to turn to steam.
eventually the can can't handle the pressure anymore, and by now the valve may very well have softened and jammed shut. pressure builds, leading to a potent little explosion inside of the boiler, overpressurizing it in a split second. With too big of a spike, the PORV wouldn't be able to vent fast enough and the lid would get shock loaded with too much pressure.
As for why i think the top can exploded: An implosion wouldn't separate the bottom of the can like it did. the can was holding quite a bit of pressure judging by how the bottom came clean off (not easy) and the stem of the water in valve had punched through the top of the can. The energy to push the top and bottom of the can came from somewhere between the two parts, and i think that somewhere was some water or possibly even leftover butane.
I think you're right, Ben. Thanks!
@@zerumsum1640 I think this is exactly correct. I just watched the previous video (new to the channel) where this boiler was built and i was wondering about the possibility of exactly this happening. Steam is dangerous stuff, glad nobody got burned or worse.
Interesting stuff:D, glad you and your helpers are ok.
(disclaimer: I'm an thermo- and fluiddynamics engineer...but not a specialist in boilers/reactors)
I can imagine 2 scenarios:
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1: Your theory: I don't know what safetyvalve you used and if it's perfectly suited for this application. maybe the pressure wasn't higher as the relief value of the valve but too high for your lid (as you said)...One could calculate this to see if this is a reasonable explainaition.
2: somehow the top cannister got pushed up over the inlet valve (maybe to thight of a fit from the floats inside the boiler(top float acts as piston)). Since all the connections are at the top, they got sealed with the alluminium sheet from the top float. So the steam couldn't exit anymore and the pressure built up until something had to go...maybe first, the bottom float imploaded and the pressure fluctuations in the boiler were enough to warp the cover...nevertheless, good safety design on the top lid;)
So:
it wasn't an "open ended" system anymore and the pressure reliefe valve was blocked
The steelplate on top is flat and can't handle nearly as much pressuredifference as the curved walls from the tube (and also not welded all the way round like the bottom end). The pipe ends were protected through the alluminium seal (altough i don't think that they would have gone earlier).
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Some thinking about the "open system"
I think you have a pretty long tube from the boiler to the exit...open ended system is kind of a relative term. The steam inside the tube needs a pressuredifference to move(boiler to outlet)...the longer/thinner the tube and the higher velocity of the steam...the higher this pressuredifference needs to be---> increasing pressure in the boiler. So if you would use an extremely long/thin pipe it is essentially a closed system...and if you would resrict the exitpipe with a stick. You increase the pressure in the boiler almost instantly.
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Some thinking about your "Flash boiler"
I get the feeling that you didn't build a "flash boiler" where you superheat water instantly in a continuous structure. I think you created a conventional boiler with a flash boiler like structure attached. The problem for me is that you still have the bomb(boiler) at the beginning of the system which is essentially a closed system...
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I don't think that you should go further with the idea of building your own boiler...The forces in combination with the enginnering challanges created with water and fire are scary and easily harmfull.
hypothetical Suggestions for an improoved version:
I think a pressure indicator on a suited place on the boiler would be very helpfull. On top of that I would implement a valve on the boiler which you can activate with a cable to relief pressure of the system manually (benefit: it makes the train thuuuuting sounds)...and hide in a bunker while testing it;)
What are your reactions? Other ideas?
Pressure relief valves don't just open and relieve. They have to be able pass enough steam/ gas to stop the pressure rising, beyond whatever your safe pressure system limit is. That may not be your actual cause in this instance.but you need to calculate how much steam the valve has to dump to maintain safe conditions and size accordingly. There is a lot of engineering in developing a safe fired pressure vessel. You may be suprised how much force is exerted on the top plate of your boiler especialy if you consider how the ultimate yield strength characteristics on your bolts,plate etc components changes as temperature rises. Take care. Superheated steam can be very unforgiving.
Rgds
Bill 6:39
As for why the plate bulged rather than the olives popping out - remember that pressure is force divided by area, the effective area that the fittings experience is much smaller than the end cap, so they are under much less load. Also as to why the pressure relief valve didn't prevent the event - seems likely that the opening in the pressure relief valve may not be large enough to relieve pressure faster than it can rise, it's probably wise to find a safety valve that opens a large area and remains open until the steam pressure has dropped well below its opening pressure.
A simple pair of rod stays would of prevented the unsupported area from yielding to the pressure this would of precluded the use of internal floats but these would of been much better in a separate chamber
I think a "bell syphon" might be better than a float valve for controlling the water level in your flash steam boiler.
Having fewer moving parts in any system helps reduce the chances of failure.
You also might want to reposition the emergency pressure release valve to a place on the boiler where it is less likely to be blocked or obstructed. In the video, it looks like the float for the float-valve broke and was able to block off the pressure release valve.
I would argue that the float valve should be retained, but simplified.
A short perforated pipe that holds a section of smaller pipe sealed on the top, but open on the bottom.
The "cup" style float is free to move up and down within its "cage", but allows an excess of steam to flow around it to the exhaust and safety outlets whilst being held firming in its position to open or close the water inlet.
The open nature of the float will catch air trying to escape the rising water, thus still floating, but also allow for pressure variation without causing any internal pressure increases or decreases and thus won't fail, explode or implode.
or a float valve made from cork !?
@@lacossanostra steam systems need to take care with materials that can break down and become clogging hazards, so cork may not be the greatest thing to add into a system like that.
Siphon won’t work, water has to be injected at a pressure > boiler pressure
akin to the monotube aka flash boilers used in steam hydroplane model racing boats. hint see video on here "flash steam by bob kirtley"! such boilers avoids pressure vessels completely, and significantly reduce volume of water at temperatures and pressures where it could flash. just a long length of piping with water in one end, heat applied, along pipe, and dry superheated steam out the other end.if driving an piston engine that also drives a water feed pump... * does not need* a feed water control valve at all.
The auto ignition temperature for propane at ambient pressure is about 300C and drops when it is under pressure. Butane is lower temps and also drops when under pressure. I don’t know which fuel cans you used, but in either case you will NEVER have cans that are totally empty. A little leak because of heating them as much as you have with put the mixture in the boiler ready for an ignition point. You have fire on one side of the boiler wall so you’ll reach those temps too easily. Don’t use anything remotely flammable as floats and you should be fine next time.
Everyone has already provided lots of options for what may have happened so I'll not try and add anything there, I'm just glad you're all okay Tim!
It may be sensible to see if you can do some basic pressure testing of the next boiler with water rather than air - it's an established practice at least in the model engineering world and may help avoid loud bangs in the future! Although from what other people have said, it may not have been the boiler that exploded at all...
Here's another theory: the top canister actually had enough gas in it to explode in the intense heat (and relatively low steam pressure of an open-ended system). And it exploded with little impact. It probably would've been a small 'pop' and that's it. But because of that, the top part of the canister became wedged on the top of the primary boiler, blocking the outlet pipe. Steam pressure built up in there, flattening the top of the canister against the top plate, which would then block the blow-off valve, allowing steam pressure to build up and crush the lower canister. After that, the primary boiler became a pressure vessel and eventually popped.
You're probably right that the pipes would've blown out of their fittings first. More likely than even that would be that some part of that soft copper tubing would've split first. I think you need to redesign your float to be something that can handle intense pressure and heat.
EDIT: to be clear, I don't think the canister exploded with fire, just from a gaseous material being heated until the canister could no longer contain the pressure within.
The explosion in the top 'gas canister' float also is my preferred explanation. Using 'used' camping gas cartridges was rather ignoring that there is residual fuel within them. Top one explodes, impales on the pressure relief valve and 'whoopti'! I also agree with other that diameter and length of the tubing in the system rather prevents it from being called an 'open' system - if it were a steam engine it would be a 'closed system' with a 'bit of a leak'.
My first thought to. Leftover gass ignited inside the canisters due to heat. I have seen it before (not in water steam thought). The explosion is impressive.
You don't need to block the outlet or the pressure valve. After the canister popped, and the pressure in and out has equalized there is now empty space in the canister, and water rushed in, slamming the canister into the top, bending it.
Maybe throw another of these empty cans in a fire pit (from a safe distance) or figure out how to test the canisters to see if they explode. It seems pretty likely.
@@fritanke2318 very unlikely he used gas canisters containing any gas and even with just a little residual vapour extremely unlikely that it would rupture without a significant amount of liquid which would have felt by movement as he held them.
Also your theory of that remnant of gas exploding ignores the facts that you still need an ignition source, not just heat so a spark or a flame and if that ruptured inside the vessel the only present is steam which won’t cause ignition inside a steam / water condition of saturation ie boiling and in fact steam is often used in industrial and petrochemical processes for purging combustible gases prior to firing etc.
You also need to have the correct stoichiometric mixture range AND a source of ignition, so no I personally don’t believe it’s possible this was a combustion explosion 💥
It was "water hammer"
When the first float collapsed the pressure dropped , the sudden drop in pressure caused the water in the bottom of the tank to flash to steam and shot the two floats above it like a cannon ball into the 3 mm plate.
The top wasnt damaged by pressure, it's impact damage.
i will respectfully disagree that the 3mm to in fact did buckle from pressure and not impact. the PRV was blocked, the water inlet was blocked, the increasing steam pressure from the blocked outlet caused the mud drum to become an isolated vessel( for lack of a better term ) and with no release available the lid buckled.
It looked like the top can was blocking the pressure relive valve. And if you make more steam than the outlet can handle you get a buildup of pressure and sometimes an explosion. That is why you never extinguish a chimney fire with water the volume of instant steam can blow the chimney apart even if it is a open pipe. ( if I remember well 1 litre of water makes 1800 litre of steam.)
Exactly my thinking. The float was blocking both the pressure relieve valve and the steam outlet, allowing pressure to build. That's pretty much the only way something like this could happen I think.
@@timderks5960 if it would have blocked it it wouldnt give an bang but an more slow release of steam when the lid gives away. So thats kinda unlikely then
Noooo nooo, I will tell you: I am glad nothing happened! Please be carefull!
I dont thing that you can trick the release valve. It is difficult to say from here, but it looks like the implosion of the bottom can sent the top can to the top, deforming it and blocking the valves and pushing your endplate out of the way.
Been thinking about the mishaps, a relief valve is designed for the safety of equipment and people. You appear to have a relief that handles gas or vapor. They may not be able to handle the volume of liquid needed to reduce the pressure expediently. The same may hold true for your port to supply your future engine. If blocked with liquid, neither can move the needed volume. Your not regulating your heat automatically so you may consider a bi metal spring and flapper to regulate the combustion chamber air inlet. I have been looking at those for my wood stoves. You may also may want to restrict the volume of water on the inlet so you never can add more more water than you relief can relieve water or steam, if a float fails. Ducting a small stream of steam into the fire box inlet may also ward off a catastrophic failure. To much rebuild is not economically feasible. It a float fails you may want it to trip the air inlet with a guillotine.
I'd say your top float was (partially) blocking the pressure relieve valve and the steam outlet, causing pressure to build. That also explains why the plate bent and the bolts ripped out, while the pipe fittings didn't: they didn't see the high pressure, because they were blocked. It would probably be a good idea to put your next float under some kind of mesh that's down a couple of cm from the top. That way the float can still control the valve with an extension, but it can never block any of the outlets anymore.
This same thing used to happen on locomotives from time to time. The danger in a boiler is not the static steam pressure, it's the potential energy in the water that has not yet turned to steam. If the pressure in the boiler suddenly drops due to a crack, or in your case the collapsing float, that water will produce FLASH STEAM which will have an explosive force. The flash is so fast that the pressure relief valves can't vent it or even open fast enough.
I was so worried of this happening. So glad you‘re okay. That‘s why overpressure valves are so important. Please invest in really good safety valves!
As others have said, maybe the valve was blocked by the floats, so also check the placement.
Remindes of an steamtrain accident in east Germany when a steam locomotive went out of water. When the train braked all vater disappeard from the part where the fire was heating but when the water went back it resultet in an terrible accident that killed the people in the locomotive as well as people om the platform where the train would have stopped. So my theory is that it was low on water because the valve did not work properly and when it suddenly opened there where a steam explosion exactly as on the locomotive.
The implosion of the float caused a sudden pressure drop. You are right on that. I would add that the higher temp water at the bottom flashed to steam before the cooler water above. The steam bubble at the bottom drove the water and floats straight up impacting the top. In short- water hammer.
i think that that your floats failed you. I can only imagine that the air inside them was getting so hot that they were being over pressurized (a water bottle left out in the sun for instance will swell as you increase the heat inside of it).
-Your top float may have had too much pressure inside of it. It then popped forcing a fair bit of energy down into the lower float crushing it and then the remainder of that energy forced the float into the lid of the boiler. (evidence by the float being impaled on the valve)
-Your valve didn't relieve the pressure because the top float may have created a seal on the lid preventing pressure from reaching that relief valve.
-That same 'new seal' at the top would also protect your fittings.
-im also thinking that maybe just the force of that float exploding inside the boiler, plus the metal being warm may have bent the lid instead of being an over pressure of steam it was just the float hitting with a strong force. After all it did impale itself on your valve there.
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I think the float(s) blew up. Cheers 🇨🇦
The float hitting the boiler top would not have done damage, the float would have just crumpled. The force from that float blowing up was what battered the boiler lid out of shape, aided by the steam already inside the boiler.
I’m just glad you weren’t injured.
@@ajaxengineco fair point, just a thought
I would also guess that the temperature in the boiler was at or above the annealing temperature (between 200c and 300c) of the aluminium alloy that the floats/empty gas cans are made from, so it was probably a combination rupture and then collapse.
To me it looks like the top float burst as it's blown its base out, it may have had some residual gas inside, probably not a good idea using gas cannisters for floats in a hot environment, you purged the larger gas bottles with water before use remember
The residual gas was my thoughts too!
@@barlichebaz8682 that oily residue of the Ethel mecaptin that has the rotting egg odor to warm you of a gas leak is still a petroleum based oil and would eventually gasify. That part of the propane or butane is not exactly measured out with precision and you may have more residue in one vessel than another of the same brand or filling time. Also the float displaced the water in the boiler and made the water boing much more efficiently. Third a pressure vessel does not generally have square lines and plates. Pressure vessels like propane cylinders have domed tops and bottoms. Because pressure exertes in all directions equally.
@@Jimmy_in_Mexico How much volume of mercaptans, organic sulphides and other odourising substances would you expect there to be in a small canister like that? I was under the impression it wasn't a very significant amount considering the extremely low concentrations we can detect it at, I'll admit I don't know that much about gas odourising beyond the basics of how older mid-20th century odouriser units work after reading the USCSB final report on the Midland Resource Recovery odouriser explosions.
@@CATASTEROID934 it's hard to know for certain. The oily residue inside the pipes during filling of the cylinders could vary depending on any number of factors. Temperature, gravity, tine of the shift the bottle was filled, time between filling of the previous bottle and the filling of this bottle. Condensation inside the lines delivering the propane from the stationary tank and the filling station in the warehouse or factory. The difference between the time the propane was delivered from the gas plant to the factory and if there was any settling in the storage containers prior to filling the bottle. I say this because I have a propane fueled truck and the fuel lines and mixer have a coating of residue from the tank. The tank is a large tank and I have used it for over twenty years. This is an extreme example, but the stationary tanks at a factory where these bottles are produced could easily be 20 years old. I have also worked in gas plants in the oil field and propane, butane and other gasses refined from natural gas are not exactly the purest products. There are margins of tolerances and gasses are separated by compressors and temperature. Propane and butane are refrigerants. They have a specific termerature they become liquid. And in a liquid state they can have suspended oils and solvents in them. So the propane is delivered in a liquid state and it remains in a liquid state as long as the pressure holds it there. But pressure increases due to temperature. And that's why the tanks have pressure release valves in them also. There are videos of tests done on propane tanks where it shows the tank being intentionally heated by a fire and how the tank releases pressure till the valve doesn't release the pressure fast enough and the metal fatigue allows the vessel to rupture. So as long as the liquid propane or butane is liquid it disipates the heat effectively from the surface but if it is not acting as a heat sink them the metals strength is compromised and failure occurs. So in this case I would lay the failure point on the weld at the seam of the bottom of the cylinder where the two pieces were welded together and inherently weaker there because of the thermal bonding of the steel. The pressure rating of the fuel tank Is calculated and established taking into consideration where these tanked are coming to be used, camping or some stove. Generally in a ambient air temperature conducive to human life forms. So exposing them to boiling water at over 212°f would not be part of the manufacturers liability. So that little tank had to have something inside it to gasify and build pressure. Also the pressure relief valve on that mass produced tank could have malfunctioned and allowed the (gasious state) of whatever substance inside the tank to build and the explosion would occure by separation of the metal at it's weakest point which seems to be the seam where the bottle was welded together. So my idea probably couldn't be proven forensically because the oils or substance inside the bottle would have been washed away with the boiling water. But something gasified and ruptured the top bottle. The bottom bottle was crushed by the exploding force. So if it was me, and I am not an engineer, but I would build a blast shield around the boiler to protect myself from steam or boiling water spewing out. The idea was interesting, and it probably would be a good float system in a different application. But too many laws of physics were violated here and it is good nobody got hurt. I'm not being critical of the man, because I figured this out the hard way in my life and have made many discoveries and tried to watch videos of things that go boom
@Jimmy in Mexico He mentions that they're of aluminium construction, I think these small cooking gas cartridges are similar to small consumer aerosol cans and don't even have a pressure relief valve but are intended that the rolled joint between the two formed pieces fails before internal pressure reaches the point the container walls could fragment when rupturing.
I think the upper gas canister blew up. Caused all the problems. Either fast, smashing through everything, or slow, causing the fresh water to stop flowing and leading to a fast increase in steam pressure.
That 3mm plate just isnt that strong over a wide area.
Prior to this incident I had considered a couple of points regarding your floats, first being that the float volume was excessive for the vessel and hence you have very little vapour space. I’d personally source or fabricate a heavier float that is actually attached to the valve stem not just pushing it. Also the float needs to be heavy to withstand the pressure inside your boiler without deforming under external pressure.
Your relief must be able to handle not only the pressure but also the maximum design flow under all conditions and I’d suggest what you have experienced that it could not vent enough steam to prevent the failure.
For your own safety and anyone else I’d suggest that you get yourself a bucket pump so you can pressure test the entire system with only the risk of getting wet.
With these sudden explosions of pressure there is no safety in the world which can protect from this.
Thats also why steam hammer and liquid hammer are so dangerous. Only preventable by design not by adding overpressure safety's (it helps a bit in smaller problems)
@@DiyNuke sudden explosions of pressure rarely occur in properly engineered boilers and IF they do anyone of many numerously redundant safety controls will in 99.999999% of cases prevent anyone within the potential blast zone from having a very bad day.
Clearly when people with little idea about the mechanical design strength, safety devices, water treatment, corrosion control etc do things by the seat of their pants engineering, the outcomes are not as predictable
I think it was the floats popping from contained air inside expanding. This caused the bottom to shoot off launching the floats onto the lid impaling it and denting the lid.
This would not cause the fittings to eject and the safety valve would not activate either. The solution is to have an open bottom on the floats so that the pressure can equalize in the floats with the boiler as a whole.
I think that with an open bottom, the floats will not float anymore, they will be at the same pressure than the boiler.
@@milhooz Imagine taking a cup and pushing it upside down into water there's a pocket of air that will cause it to float. If water gets into there it's okay because steam will naturally accumulate in there I believe.
This all theoretical, and would require some physical tests.
@@deathclawow Yes I see, I'm not sure it would work but would be interesting to test.
They did not contain air, they contained butane vapour, which caused the explosion.
I agree. The system is open, but the gascontainers were closed. They probably bulged out, and blocked of the bottom of the tank by pushing againstvthe sides, making it a closed system.
I have no idea but love watching your inventions... BE SAFE
Tim!! Thankfully you two are still breathing and with us! - you insulated the stack and the "heat sink" is no longer there, so the boiler would be hotter. The top gas can looks as and others have pointed out the same, to have been pushed up and blocked the pressure relief valve - put the pressure relief vales someplace else, and even have 2 - 1 on top and 1 on the side. - If you can put some temp thermal readers in the system some place, thermal-couples and a multimeter would work. It also looks that when the top can blocked your pressure relif valve, the water valve was now left open and dumped water into the system, then it exploded, this all happens really quickly...
Your evaluation of the incident is correct, the implosion of the floats resulted in a pressure drop sufficient to cause a significant flash to steam of the water in the boiler resulting in a sudden pressure increase which overwhelmed the relief valve. The boiler cap screws where thankfully the weak point.
I think I'm leaning towards what Matthias is saying, the sealed floats were the problem I think. I know some people are saying there is a lot of resistance from the long steam path, but I don't know enough about that. It certainly seems like the sealed floats could explode under high heat. Possible to find ones with a relief valve, or maybe you can add your own or a tiny one-way valve in the floats so they can release their pressure but not fill with water. My initial thought was an opening at the top of the float to let the air inside equalize in pressure, but without letting in water, but you might have to switch to a single float situation with that.
At any rate, fascinating stuff as always, and I'm very happy nobody got hurt! Cheers!
Wild guess made 2:15 in. That there was residual gas in the canisters which exploded. And this forced the lid up the 3mm. But going to watch to the end very interested!!! - Very glad you and loved ones were all ok!
Think your theory is way better. I couldn't see how the gas would explode by being heated up in a wet environment. But noticed the damage to the canisters and how they could act like a ram and blast up to the lid. But wanted to write thoughts before hearing / reading others.
Hi Tim. Here's the fun thought. Contrary to my previous disagreements with you in the comments, I think for the first time you actually DID have a flash boiler there was some interruption to water inflow, sticky inlet valve or whatever, this meant the boiler was soon way above boiling point. Then when the water flowed again it hit the hot surface and flashed into steam. Which is a violent process. And I would suggest that because of the lower surface area that yes the steam fittings were stronger than the 3mm steel plate in this instance given the pitch of the clamp bolts.
Whatever you do next, please as others have said, do a static hydraulic test before you operate any kind of closed system. A simple way to get the pressure test done is to temporarily fit a grease gun into the system. Add a pressure gauge, then fill with water and pump. I would like to see a test done at twice safety valve pressure to give that 2 : 1 confidence.
Also please read the comment by Steve Allen on here. I totally agree with his engineering view on this, and he's explained flash boilers better than I did . Regards Gary
This type of group conundrum is awfully good for the comments, more please..!
Awesome Build!! I typed two paragraphs and then realized Matthias Wandel already wrote basically the same thing. I do have a few things to add. Pressure relief valves of that style are not designed to handle explosions, only bleed off pressure to prevent an explosion. You may want to consider building yourself a rupture disk of large diameter so this cannot happen again. A large diameter pipe can be added to the exhaust side of the rupture disk to divert steam away from the operator. Also don't use floats with flammable gas inside that are only rated for low temperature and low pressure, that is the root cause of your issue.
Your explanation seems reasonable. I think the float system is almost certainly the culprit. You should replace the water inlet valve with a more traditional CLACK VALVE. A simple stainless steel ball bearing one way valve. As far as the pressure releasing valve I would replace that as well with a more traditional spring loaded stainless steel ball valve. It is essential that any boiler system has a blow off valve that is capable of relieving pressure faster than the boiler can increase pressure. The standard boiler test for locomotive type boilers is to bring the boiler up to valve relief pressure then crank up the boiler by opening up the valve that fires steam up the chimney, cause a massive rush of air through the fire increasing steam pressure. The safety valve blowing off must stop any further rise in boiler pressure. Another issue with boilers is having to high a water level, the small amount of steam space allows pressure to prevent the water from boiling off, this causes a buildup of potential steam held back in the form of super heated water, as soon as steam is released the water instantly replaces the steam and water level drop steam space increase causing a rapid boiling off. The relationship between pressure, temperature, steam space is controlled but has a hysteresis loop involved thus the right combination can cause a massive spike in pressure, easily enough to remodel the boiler shape. May I suggest you build a real flash steam boiler , they are much safer as the do not use a volume of pressurised heated water. The concept is simple, create a very long coiled metal tuBe, place this in a fire, when you pump water into the tube it will instantly flash into steam, this then progresses along the tube increasing its pressure and becoming superheated, dry steam. At the end of the pipe connect your steam engine with a bypass valve to allow all the steam to escape and not power the engine, by varying the water pump and adjusting the bypass valve you can control the engine speed. It is best to ad a safety valve just in case the engine stalled when the bypass valve is closed. Often two water pumps are used, one is a priming pump used to start things up and the second is driven by the engine and maintains the flow once started. A typical coil would be like the one brewers use to condense, but more overlapped coils. Consider yourself luck superheated steam will melt the flesh of your bones and from memory the largest ever (until recently) civilian explosion was caused by a factory boiler exploding in an American town.
That's what I'm trying to make, Steve. The problem is balancing the water input with the heat. Hence the float valve. It's easy with a gas fire - you know how much water to allow into the system - but this is wood fired so it has to be balanced continuously..
@@wayoutwest-workshopstuff6299 hi there, you are missing the point, you are using a reservoir of water that is being heated, this requires time and a lot of heat to get to the point of creating steam. An analogy if you put a pot on a wood fire it will take several minutes to come to the boil, if however you put a teaspoon of water on the fire it would boil really fast. So you take 30m of coiled copper tube right in the middle of the fire. If you force a tablespoon of water through a one way valve into the pipe it will flash boil into steam within seconds, now add another tablespoon, it will push the steam further into the pipe making it hotter and will boil itself. The important thing is to let the pipe get up to temp before introducing the water. The small amounts of water added will have no effect on the temperature of the copper pipe because the fire can add heat energy faster than the cater can use it to boil.. check out this video it uses blow torches for a high speed boat. Your system relies on bringing the water up to boiling point than as you bleed off steam you introduce more water, instantly chills the boiler and it stops producing steam so the pressure drops.this is why most full sized steam engines have a variable volume pump run from the steam engine that adds a small amount of water to the boiler right next to the firebox, with every rotation of the crankshaft. This avoids the chilling effect. Out of curiosity what size engine are you hoping to run?
@@wayoutwest-workshopstuff6299 th-cam.com/video/fPWuW8kBM5c/w-d-xo.html. Missed the link. Note there is no water reservoir in the heated area, just the tube.
@@steveallen8987 I know well how they work, Steve. But you're missing the point now - as I said, it's easy if you have a constant heat, but I'm trying to allow for variable heat...
@@wayoutwest-workshopstuff6299 ok I get you now, so the floats appear to be the main source of failure so how about a smaller rigid float with a very small hole in the to to allow equal pressure inside and out and small enough to prevent water entering or perhaps a small curved pipe connected to hole to keep out water. If the size is smaller perhaps a guide to keep it in position?
My theory! ::
If you look at the dismantling of the boiler and removal of the floats in sequence, and then also watch the video of the boiler being made, with the insertion of the floats, the construction of the floats (used gas canisters) have a rolled joint at the base of each cannister (a weakness). and the top part of the cannister is press formed from one piece of tin. - the rolled joint is the weak point of the can.
So I think that the top float expanded and exploded and impaled itself over the inlet valve and PRV and caused the tank lid to buckle from the overpressure reaction.
In the overpressure event, it caused the lower float cannister to implode (because its all crumpled up when removed from the chamber)
The floats use basicly the same construction method as a coke can but are used upside down - watch a coke can explode and they nearly always blow on the rolled joint as that is the weak point!
Give me your thoughts,
Im just a farmer :P
we all learn from our mistakes, i built a donkey (wood heater for water) but the chimney goes through the centre of a 3mm rolled steel vessel, the chimney was a 2mm thickness x 76mm square tubing, m/s , it worked like a charm, then i connected it to mains water, 450kpa, with a relieve valve !!! but.... the chimney was squashed flat as a pan!!! the full lenght of the water vessel, causing a tear around the bottom and top, remedy... i used a 76mm round pipe 3mm thick, this time it works, now 13 years later i learned from your project :)
This was a happy learning experience because nobody was hurt.
your theory makes perfect sense. As to "why is the plate bent instead of the tubes popping out", itll have to do with how pressure works.. pounds per square inch.. the ends of the pipes only endured a fraction of the energy because less square inches. the plate however has a great big surface area for this pressure to work on.
One of your two floats still had a little butane/propane in. The vapour pressure of the butane/propane is always greater that the vapour pressure of the water at the same temperature and so the bottom blew out of one of the floats and the pressure wave crushed the other one.
My theory? You're an utter genius whose R&D is unparalleled. My only observation was that the upper cannister was impaled by the valve at the top. There must have been a lot of force under the upper cannister for that to happen.
I think it's pretty cool that two of my favorite TH-camrs follow another of my favorite TH-camrs! Nighthawk, Matthias and Way Out.
No "I told you so", just an, "I'm glad you didn't get hurt."
To pop the lid is easier than the pipe because the area of the lid is larger. Like a hydraulic piston, where your lid is the piston base with seals, and the steam is the oil.
You found the top aluminum float crushed against the boiler top! clearly it got pushed up hard enough to obstruct the pressure-relief valve and push out the top of the boiler. I would guess that it's implosion dynamics widened it to form some sort of seal that allowed steam pressure to build under it.
yeah this result is exactly why i said i was so relieved last video, when you mentioned adding in the pressure relief valves, etc.
steam engines are novel and great, but they really are not something to mess around with. and there's always something you could never predict that messes it all up
My theory is that the top cylinder definately exploded because there was no deformation of the cylinder walls but it blew its end off, that means the force came from within the top gas cylinder, I therefore believe there was spontaneous combustion of the remaining gas left in the assumed empty gas cylinder the result being the bottom cylinder imploding and the top of the top cylinder forming a seal against the pressure relief valve so the boiler top ended up being the new safety valve.
I wrote my theory and then read the other comments, it looks like a lot of others have come to the same conclusion, Tim, have fun but play safely.
I think you are on the right track. That’s what I was thinking! Make On my Friend and nice to meet you.
I think you are right on the money there. Sounds perfectly feasible to me, altho' I never did much fancy those roofing bolts! Brave fellow, be careful and can't wait to see where you go with it. Cheers!
I was thinking along the lines of your theory and that the pressure relief valve didn't work because the pressure changed too quickly for it to cope, but I don't think that the stick had anything to do with it, I think that the pressure inside the chamber was just simply too high for the floats to handle.
I agree with Matthias Wandel - a solution would be to make floats that were slightly flexible so they could expand or contract with the temperature changes to a point where they were stable.
This is what I think happened, which explains what you can see very well:
So the float either explodes from internal pressures, or the lid collapses into the float. This suddenly means there is a lot of space on the top, as the float is now open and empty and WATER RUSHED IN TO FILL THAT SPACE. That means you now have a body of water moving towards the top. And when the space is gone, that water will slam into the top, bending the 3mm top. Basically, it's a water/steam hammer effect.
So the pressure valve doesn't trigger, because there is no high pressure at any point.
I wonder if you filled your canisters with spray foam if that would give them enough structure to not collapse under the pressure. I am looking forward to seeing what you come up with. Thanks for sharing.
Nicolai Itchenko already said it, but I’ll say it again for emphasis. It looks like residual gas in the lower canister auto ignited, and exploded, throwing the upper canister into the relief valve, blocking it, and the steam outlet. Then (my own analysis) I think the water in the tank expanded, with all the new area available with a blown open canister, causing a huge spike in pressure, which blew the top can up hard enough to puncture it and deform the 3mm steel lid upwards, creating an escape path for the pressure. Which probably saved your life. God bless you man, keep up the project, but please be careful
I’ld back up your theory, and add, with the sudden collapse of the first float, or a leak from the cap, the pressure drop could have flash boiled nearly all that water. I think steam is 13x volume of water (temperature dependent?), probably caused a shock wave that deformed everything before the relief valve could relieve anything. Same for the open vent. A shockwave would have deformed everything in its path as fast (speed of sounds) as it moved.
Really really happy you were moving away from it, how’s you hearing?!
I don't agree with the collapsing float theory, I think the top float exploded and crushed the bottom float while also denting up the lid when it impaled itself on the valve.
It's an open system, but those gas canisters are very much well sealed. With butane/propane they turn to liquid in such a container without too much fuss, but at those temperatures even the remnants of gas or even water inside the canister would cause this.
Get another empty canister and throw it on a bonfire - you'll soon find your problem! :)
I think this is correct, Either in the form of water forming a steam bomb as the temperature goes above boiling in the float, or if there’s a little oxygen and fuel in there, you could also have an explosion. But my guess is the former-The close environment the flow became over pressurized by internal water turning into steam. Closed floats inside the boiler is probably an idea that needs to be re-thought. So glad you’re OK! PS Pressure cookers have multiple forms of steam release. The pressure release as well as a gasket that will blow out on overpressure. Maybe you should adopt a silicone gasket in addition to the relief valve?
Keep your chin up and keep going! You're work is amazing!
I just read some of the other comments I have to agree with the combustible fuel in your floats being the issue. That was a fast and obvious volatile detonation. Kind of a bomb in the bomb theory. Very cool project.
Looks like the feeder broke and ran out of water. But I guess the pressure in the tank was to much for the cans and the can blocked the relief valve. I really love the videos
Your theory sounds plausible and very interesting. I was also wondering if the float bottle smashed against the top of the boiler somehow sealed off the valves, couldn't quite tell from your disassembly.
I think it's more likely that the top butane canister suffered an overpressure failure due to either super heated butane or more likely steam trapped behind the one way valve. It probably developed a low pressure condition after the first use and water was drawn in as it cooled. This water was boiled during the second test but couldn't escape. The pressure relief valve on the main boiler chamber probably couldn't reduce the pressure quickly enough and may have been obstructed by the sheet metal from the butane canister. Glad nobody got burned.
I agree with alot of the other comments in that basically you need a redesign of your feed water system. The float valve is an excellent idea for a small boiler system though the float size is a bit of an issue. Ideally you would probably want a float that is ¼ or less the size of your tank so that you reduce the risk of running your boiler dry and blowing up your set up. It also ensures that in the event of a catastrophic failure of the float, the pressure relief valve doesn't get blocked. It may be more prudent to use a continuous feed water supply and have it come in from the bottom.
3 effects did happen here:
1st pressure: it raised against the air filled gas bottles and started to compress them because the bottle walls were much thinner than the outer steel wall.
2nd the temperature: also air expands in rising temperatures and pushed against the pressure from outside.
3rd the stick: What did you think when putting a stick in the outlet?
Now combine all. Bang!
You can be happy that you weren't injured.
Thanks for posting the details of the mishap. It would have been easy to just keep that a secret.
Flat plate is _terrible_ at resisting any significant pressure. Domes and cylinders are far far better. Of course sometimes there is a need for a flat surface in a pressure vessel. They fix the weakness with stays that tie the flat surface to a strong surface facing it. Do a search for boiler stays and you'll get loads of information.
My other thought is your safety relief valve. Is it for water or steam? If it's designed for a water heater, it will not function as intended for live steam.
Vessels here in North America designed for >1 atmosphere need to be ASME rated. Pressure vessels are a big difference, for safety reasons. Your top wasnt domed, and your pressure raised. You are measuring temperature, but not pressure. I caught your other video, but i forget if you had a PRV release valve. Install a pressure gauge.
A pressure gauge won't help either if it's blocked, like the pressure release valve and the steam outlet probably were by the float that was impaled. It might even give you a false sense of security.
@@timderks5960 Your PRV and pressure gauge can be in different locations. The float didn't create a full blockage, as the top of the can ruptured by the seal. A gauge is standard for all ASME rated tanks. As well, the float wasn't big enough to seal the outlet in the first place as it was functional. If the float had completely sealed it, it would have been perforated on both sides and wrapped around the PRV and the steam outlet.
@@BeeRich33 It's almost like you have X-ray eyes that can also go back in time. Impressive. The float doesn't need to create a full seal, it only needs a tiny part of metal to block the openings, either fully or partially, to cause a problem. Given how messed up those cans were, there's a high probability that something like that happened.
About the boiler being functional: Who's to say it wasn't just residual steam coming out of the pipes, and the outlet was actually blocked at that point? You can't know for sure, neither can I. You say "install a pressure gauge" as if that's the end all ultimate solution, and I'm just saying it's not, which it isn't. I'm not saying it's not a good idea, but it definitely takes more than just installing a gauge to prevent this from happening again.
Glad you’re safe Tim! You will get this sorted.
I am going out on a limb here to say water hammer. Check out the forces involved when a vacuum chamber implodes under water, which is essentially what you had. All of that energy from the implosion would have been transferred to the water and from the water to casing. Flash boiling can be violent as well which could happen with a sudden drop in pressure as you discuss in the video.
I think the pressure in your boiler got high enough to crush your float cans, this could be combatted by pressurizing the floats.
The top float looks like it got melted by the hot steam a bit and the weakened aluminum was punctured by the pressure control valve it was supposed to operate. This covered the release valve for the steam and built pressure in the tank. Then "bang".
Basically your boiler couldn't release enough pressure through the holes it was given, especially after a restriction was introduced by the top can crushing into the ports.
My husband was a Journeyman fitter/welder for 42 years for one company. He believes your pressure relief valve was blocked by the implosion of your float. Not that it was an issue this time, but he recommended 70/18 rod for your welds. Incidentally, he said steam pipe blowouts at the power plant (which was where he worked for 42 years) can cut a man clean in half. Happy building, good luck and be safe.
I am glad that you are safe.
In a previous comment I suggested modular, separate systems.
As I understand your analysis: You have combined a water-level governing device with a water-boiling device. "Bang!" because if conflicts between the two sub-systems contained within a single space.
Proposal: Separate these two components into modules so that one module CANNOT interact with the other.
Then at least you have removed one BANG possibility.
Here's a poor analogy: My toilet system has a module that governs the input flow of water and shuts off when enough water is in the cistern. A second module uses the water to flush wastes into the sewer system.
Chris
Here in the South of US steam locamotive excursions and old steam engines at County Fairs are popular. Every few years one explodes and causes tragic events.
I believe your theory is correct.
In addition the heat may have weakened the aluminum float.
A safety valve can’t overcome a pressure spike.
I don’t believe your safety valve should be used for boilers, It looks like something from a hotwater heater.
If you ate trying to create high pressure flash steam use copper everything, it will split but shouldn’t grenade like steel.
Your lid wasn’t stayed properly, I wouldn’t use steel less than 1/4-5/16” and much much heavier if it isn’t stayed.
I never build anything that runs higher than 150 psi.
Personally I would build a porcupine or water tube boiler & stay well away from high pressure, at some point scale factor no longer applies, heat & pressure do weird things and stuff HAS to be properly engineered to avoid injury.
I hope thats helpful.
Please keep in mind that the forces of the steam do not only depent on the preassure but on the area. With a force of one kilogram per cm^2 at a pressure of one bar, I assume that the force on the top of your boiler was (at 3 bar) around 1-2 tons. But I don't think that this is enough to harm your steel plates or the bolts.
Why did the relief valve not work? Take a look at 2:22 and you'll see the answer: The upper float was pressed against the fitting of the relief valve and thus blocking the passage.
The open exit pipe, reduced or not, has not enough cross-section to handle a sudden increase in pressure. It is more like a choke. So the increasse in steam pressure could've not been held in check by neither the exit pipe nor the relief valve resulting in blowing out the weakest point.
Why it bend the top and didn't blow out the fittings is simple: Force is pressure times area and the top has way more area than the cross-section of the fittings. In addition the fittings experience an outward force from the pressure inside their passages (the bore from inside to outside) which presses them firmly into the bore of the boiler. So the big massive plate became the weakest point. The most impressive thing about the bent top is that the screws were able to hold it in place. I'd have expected them or their bores in the plate to give in first and let the top fly away (which thankfully didn't happen, the results could've been much worse).
Just out of curiosity: How much water held this boiler?
Sorry I have not been back with those ideas to share. :(. Knowing your working with higher pressures and superheated water radically changed what I was going to suggest so I've been reflecting on the designs relevance in light of these new pressures. I'll make suggestions when I have a better understanding of what your trying to do and the parameters. Glad your not hurt! 🤕!
I'll take a guess that the top float blew the bottom off from low pressure in the boiler. I've seen canisters like that before where the valve is designed to be filled by pressure and engagement much like a schrader valve. When the boiler was pressurized might have been able to push the valve in allowing steam and air to enter the canister till the high pressure side of the boiler and low pressure of the canister met equilibrium. When the boiler cooled or was operated at lower temperature the pressure in the canister cant escape and it blew up from being over pressurized and being open ended didn't help it because without building enough pressure in the boiler there wasnt much pushing back on the canister to keep it from yielding.
Your theory sounds correct to me.
The lesson is that you need to make the next float out of stronger material.
So it can build up more pressure before it explodes?
@@ShadeTheif that's how boilers work 😉
@@ShadeTheif
The thing didn't explode simply because there was too much pressure because the pressure relief valve will let excess pressure out.
He explained the chain of events that caused the tank to blow, and it looks like you don't understand what he said.
The floats imploded, and that caused a sudden DROP in interior pressure. A tank of water that's already above the boiling point is kept from turning into steam by the vessel keeping that hot water contained under pressure. When something gives and the pressure drops quickly, all the water that's hot enough to boil will instantly turn to steam. Since steam takes up much more space than water, you have a SUDDEN and LARGE increase in pressure inside the tank. It's so sudden and powerful that the pressure relief valve is unable to let it escape the tank fast enough. Only a ridiculously overbuilt tank can handle a huge pressure shock like that.
My suggestion to make the floats tougher is the sensible thing to do because the floats' ability to resist imploding is just as important as the tank's ability to resist exploding.
Clue 1 don't use propane cans as floats. They are made to hold pressure not be compression.
The pressure valve is not under pressure but the propane can will have the internal pressure vent when hot then it will implode and drop the pressure in the chamber thus boiling the water.
Maybe do what all pressure vessels are required to do and get it certified before use.
After all the law (UK) was brought in to stop tinkering with steam vessels because they like to explode.
Biggest lesson I have for you would be to ALWAYS have the camera running.
It does mean you will have a lot of junk footage to discard, but you will never miss a moment to upload to TH-cam, as a bonus if your quality is good enough, you can actually get clues to the failure in the moments prior to the explosion as well that can make the forensics a lot easier.
Glad you were not injured. A potential major "brown trouser" incident.
The relief valve will have a maximum flow it can release. It may have released for a short time but the volume of steam needing to be vented was far too much for the small relief valve. Pressure vessels often have a busting disc to prevent the pressure vessel catastrophic failure under a rapid over pressurization. You can achieve the same effect by having a piece of pipe with a cap which is the weakest link in the chain. The big challenge is figuring out the maximum volume you need to release and the thickness/strength of the material. Complicated calculations.
I think water may have been trapped under the lid in some way. If this happened, it would not take long to create a pressure wave to cause the bang.
Dave.
First off I'm glad you're safe. I'm sure you gather that the floats were the problem. Based on how you plan to use the boiler, it would make sense to manually control the feed water flow since that would be your "throttle" and not have to worry about the floats. Add a sight glass or test cocks open to find the water level. For what it's worth. I think the float expanded from the heat and sealed the bottom half of the boiler from the top where the safety valve was.
My theory: I think your bottom float imploded under the pressure from within the boiler, being closer to the heat source it weakened first,
That volume of air from within the float is then forced out at extreme pressure, hitting the top float and launching it into the roof of the boiler, impaling itself on your fittings and releasing it's pressured ait in the same moment.
The force of the top float hitting the top plate combined with the increase in pressure, buckled the boiler roof until it broke the seal.
Despite being open ended, the sudden increase in pressure had nowhere to go but through the top/main gasket.
🤷🏼♂️? Thoughts
There seem to be good comments guessing what happened, so my only thought would be to add a rupture disk in the future to prevent explosive failures.
I think the top float (the silver can) was touching the side of the boiler and the air in the can expanded and because the float itself was a pressure vessel the pressure kept builing inside until the bottom of the float gave way crumpling the bottom float (the red one) and the top rocketed up and deformed the top of the boiler causing the explosion.
I have no training in anything to do with this. I am just an Australian who really enjoys the content you produce and thought they could give their 5 cents as to what may have occured.
I think your dissection was spot on.
Not a stream engine doctor but maybe use a high temperature resistance, low density solid material instead of the cans. Some sort of plastic foam might give you the boyant force but remove the risk of rapid collapse. The foam could be crushed but it might happen progressively. Instead of boom you just get a fizzle as the boiler floods...
Alternatively a composite float with a "hard" outer casing and rigid foam internals...
I think about an idea of cutting a hole in the bottom plate of his boiler then using a fire extinguisher vessel with the bottom cut out and inserted into the bottom of the boiler and welded into place would give him the flash boiler efficiency and having a domed top would resist the pressure because that's why vessels have domed ends like propane cylinders. Then coming up with a positive displacement pump to inject water at the same rate as the water is being converted into steam.
My best guess looking at the outward bend in the boiler as shown, is that you did indeed have a blockage preventing release of pressure, then kaboom! Lol. 😂
Glad your not hurt as it could have been lethal.
This accident gave me a great idea 💡! Design in a replaceable weak spot using smaller guage steel that will give way before ruining your tank if the other fail safes fail. Just make sure this replaceable thinner metal is located in a safe place, jic. :)
Redundance in safety is key!
To bend the top plate as such, shows the immense power of steam. I am impressed. But, was the relief valve new, used, perhaps corroded inside from prior use? But I would imagine you had used a new one. It does look to me that the system had a need for twelve bolts as opposed to the six. Hot water will only turn to steam when it hits air, so if a few inches of metal between bolts bent, suddenly giving a lot of air, perhaps the major portion of water turned to steam all at once, giving you a nice awakening. But the other explanations below sound reasonable too. Good luck.
If you open propane tanks there's sometimes a little bit of oil in the bottom which they use to make the characteristic propane smell. I say there was a little bit of that oil in the top float can and it built up pressure until the bottom blew off. If you pay attention to the direction of force the top of the can blew upwards and the bottom of the can blew downwards crushing the can underneath it. This problem could have been easily avoided by either drawing a vacuum inside of your floats or by putting a small valve or hole in the cans.
very interesting and yes. A simple pvmrt function expessed as a time dependent differential equation would support your hypnosis.
Looking at the two floats, the bottom float pretty clearly was crushed, but I think rather than being crushed, the top float exploded - the bottom of it popped off neatly, with the seam between it and the top being the weakest link, and is bulged outwards, while the top got jammed up close against the top of the boiler, certainly tightly enough to prevent steam from leaving it. That would also explain why the fittings did not pop off - they were shielded from the increase in steam pressure by the top of the top float, and so the pressure was able to rise until the top sheet of the boiler failed.
Now, why did the top float explode? The simplest explanation would be that it wasn't quite empty, and the remaining gas inside it expanded with the heat and caused the explosion. Though then the question becomes, why did it only explode now, and not the first time it got heated?
You are right. Floats inside a pressure vessel would have to be non compressible and also float (?) 3mm not thick enough also twice as many bolts in the circular flange.
Your theory seems valid...lower pressure/dry steam deformed the upper chamber, superheating the lower chamber, and the vaporized wet steam expanded rapidly causing the over pressure, which hit with a surge, which the relief couldn't handle fast enough. Wow, that could have been worse on you...so, you might say, going for the camera, and YT saved ya! Keep learning for us...way cool content...
It's asking for trouble using enpty gas cannisters for floats, what gas was left inside got so hot it exploded creating in effect a bomb. It wasn't the steam pressure that caused the failure it was the floats
I think you need a pop off in addition to your pressure relief valve.. I deliberately made weak point that can pop off in the event of a failure like you described at the end of this video rather than potentially causing catastrophic failure.
Really good video! We learn more from unexpected results because they make us stop and think.
Hi Tim, I believe it to be residual L.P.G in the cylinder, which then became pressurised L.P.G which then ignited at compression point which caused flash explosion within combustion chamber(float area) which then combined with superheated steam which instantaioniously released to atmospheric pressure, also imploding cylinder blocking P.R.V thus resulting in it being non functional..a scary moment!👍
I agree with the float idea. The heat from the steam increasing the pressure in canister, (and if there was some gas in it) Stay safe. Remember, even Whistlin Diesel almost got killed recently, even if it was faked for Diesel Brothers
Also consider testing the system with compressed water, you'll need bungs. But you can generate the same force a lot safer using uncompressible water rather than steam which is a big scary spring storing vast amounts of energy.
Auto ignition of the gasses in the one of the gas cans seems the most likely explanation. I experienced something similar when I used silicone spray on my car's spark plug connectors - a few minutes of running the engine caused auto ignition of the propellant dissolved in the silicone and blew all the connectors out of the engine.
The top can was squished against the top and probably blocked the safety valve and outlet, so the lid deformed instead.
As you noted it's hard to explain the steam doing that.
Could it have become completely filled with water, which then expanded when heated?
Were your float cans completely purged first? Any amount of fumes left in them could easily be explosive at that temperature. You may have had a contained explosion within the boiler.