DIY Pressure test vessel?

[dumpsterDiver]

Does anyone have ideas on resonably cheap and inexpensive DIY chamber that could test a small camera housing down to 250 feet (say 125 psi)?

I did a search and a guy was talking about welding steel which I can not do.

I want to be able to repeatedly check a pretty small housing, it will probably fit into an 8-inch PVC pipe. Any ideas?

I'm thinking of a capped 8-inch PVC pipe, filled completely with water and then using a regulator or something to pressurize via a BC inflator fitting screwed into the PVC wall. Not sure how to secure the removable lid safely?

Could a screw-on plug with maybe a little telflon tape work for a lid? I am hoping that with the vessel filled only with water and using a tiny volume of air to pressurize the device that if it does fail, there will be very minimal potential for personal injury..

Also if the lid of the test vessel leaked a tiny bit of air this should not be a problem since the regulator should keep the pressure up???
?????

 

[H2ODog]

Using PVC will work but you'll want SCH 40 at least. You'll be able to thread a tire valve stem into the end with minimal effort to pressurize your pot and for an actual pressure gauge. The main problem see is 8 inch pvc will be expensive, in the range of $40-60 for each fitting maybe more. I haven't bought any recently (for a year or two) though so thats a guess.

I've heard of people using old steel tanks for pressure pots. This may be an option or something similar even if you have to find someone to do the welding. That may be the cheaper alternative to purchasing expensive pvc fittings. There should be someone around who won't charge you and arm and a leg for a small welding job.

 

[dumpsterDiver]

I can get lotsa old aluminum 80 tanks for cheap and could cut the top off pretty easily with a saw, but how to make a removable top (for cheap with a tank?)

 

[jeraldjcook]

The walls of an AL80 are pretty thick. Cut the neck and dome off the tank. Drill 6-8 holes around the rim of the tanks. Tap holes and insert all-thread (that's what we call it around here, threaded steel round stock) leaving 2" exposed. Make a 1" plexiglass top, drill 6-8 holes to match all-thread, and fasten with wingnuts. Use some sort of flat rubber as a gasket.

What do ya think?

 

[jeraldjcook]

And if you could get your hands on one, I'd use a small compressor instead a regular to pressurize it. Get a 25 or 50 ft hose, most compressor have a pressure regulator, get a safe distance away and start turning up the pressure. Doesn't get much safer than that.

 

[don Francisco]

I use a pressure cooker, the Mirro brand type where pressure is regulated by a weight placed on a valve stem at the top. That and a bicycle pump with gauge is my test vessel for anything that fits. The valve stem is similar to a Schraeder (automotive tire) valve and the pump thumbleck fits on pretty well.

Using the pump & gauge, I can dive anything that fits to about 150 (75psig) feet or more safely and easily. The safety valve blows out at about 125psi. Pressure tests can be done either wet or dry on anything that fits. I've used it on my computer, & camera housing both very effectively over the years. If testing a computer by simulating a dive, remember to bleed the pressure off (ascend) slowly, otherwise it myght go into error mode. The only drawback is that you can't see what is happening so, for example you can't learn about your computers Deco screens.

One caveat, any charged pressure vessel contains lots of energy, so be sure to read the manual for any pressure cooker thoroughly before pressurizing. If you want to test the safety valve, fill the unit with water leaving a minimum air space, then add pressure.

BTW, besides the low cost, another benefit of this pressure test vessel is that between tests it works pretty well as a cooking vessel.

 

[Randy43068]

Check out Oxyhackers book at Airspeed press. It has very good instructions.

Vance Harlow's OXYGEN HACKER'S COMPANION From AIrspeed Press

 

[NorthWoodsDiver]

If you want any welding done I can help. Obviously shipping would get involved then but I can weld just about anything you need. I may even have some 8" steel pipe laying around. Steel prices have sky rocketed though so you are looking at about $1 per pound maybe a few cents less. I can do it outside of work for just a little compensation for time and driving. Let me know if I can help.

 

[1_T_Submariner]

You might want to avoid "Plexiglass" that you would buy at home depot or hardware store. Try to find an industrial supply and get "Lexan" a lot safer.

The walls of an AL80 are pretty thick. Cut the neck and dome off the tank. Drill 6-8 holes around the rim of the tanks. Tap holes and insert all-thread (that's what we call it around here, threaded steel round stock) leaving 2" exposed. Make a 1" plexiglass top, drill 6-8 holes to match all-thread, and fasten with wingnuts. Use some sort of flat rubber as a gasket.

What do ya think?

 

[Brewone0to]

Or you could engineer a tank which when 1/2 full could submerge your item.
rig it with a way to raise your item being tested out of water.
Perhaps a screen or hardware cloth above water level.
I'm picturing a 10 gal fishtank with a pce of lexan glued to the top with an O-ring sealed hinged access door on one side.Fill tank to just under grate,install item to be tested,invert tank submerging test item,perform leak test.
Just for safety's sake, how about pulling a vacuum on the gas/air portion of the tank.
This way when a leak is shown it will be gas/air escaping from tested item, not water entering it.This way one could also test for leaks after battery changes on computers/dive watches.
***If Leak Occurs During Tests,One MUST Invert Test Tank Before Equalizing Pressure In Test Tank.***
Hope this helps you out