DIY Compression tester?

[Charlie99]

Granted this'll only let you test to 4ATA (130')

I was thinking about 99 FSW at 4ATM.

The linked device can pressurize to the same level as 132 in saltwater.

Gauge pressure vs absolute pressure; atm vs ata; and psig (or psi) vs psia; can be confusing.

The pressure paint pot is rated 60psi, which I assume is 60psi-gauge or 4atm. When used at sea level that will be 75psi-absolute or 5ata (5 atmoshperes-absolute), which is the same pressure level as 132' below the ocean surface.

 

[james croft]

Gotcha!

 

[TravisD]

Just remember the rule about Harbor Freight tools: Eventually, every tool from HF becomes a hammer.

 

[M_Bipartitus]

I hear corny kegs (5 gallon soda/beer kegs) work well, if you have any friends that brew they could hook you up. Sometimes good deals can be found on used ones, too.

Kind of a small opening on the top so might not work for a lot of cameras...

corny kegs are rated up to 130psi.

I had not thought of that, I have a corny keg. I could use that for the light I'm working on.

 

[Divemaster-K]

aluminum 80 with a clear acrylic plastic top which works nice because you can see though the top.

Being able to see the equipment being tested is a must, which is why store-bought pressure tanks will not work. I'm thinking of something along the lines of a cylinder (old A80) sandwiched between two 1" thick pieces of plexi with flat rubber seals and held in place with rod bolts and wing nuts. The cylinder would have two fittings: one for a needle depth/pressure gauge, the other for introducing pressurized air.

I wish to use this for testing home-built lights at depth without getting my feet wet.

See my idea on paper below:

 

[superstar]

I can't seem to upload the pictures of my test cylinder, the photo file is too large?? I will get the wife to do it for me this weekend.

 

[Waterskier1]

I think this is still on subject, if not, just delete it.

I see that Divemaster-K and probably others may be using a depth gauge versus a pressure (in pounds/in or bar) gauge. This makes sense, but what caught my eye on this project was a way to check the accuracy of my depth gauge. My analog depth gauge reads quite different from my computer's depth. But, I have looked around and can't find any way of adjusting (calibrating) that depth gauge. It's an Oceanic, but I don't think that matters. Does anyone know if one can calibrate an analog depth gauge? If so, what accurace and tolerance pressure gauge would I need? It almost seems that the depth gauge has higher resolution than a standard PIS pressure gague. Note: I haven't looked at digital gagues, but in most cases, even though you can read to many significant digits, the actual sensor driving the display is the limiting factor, in that it's tolerance is might wider than the display.

Any thoughts?

 

[superstar]

This is what I came up with.
I welded a plate on the bottom of a piece of pipe. I then welded some square stock on the outside for the cover plate bolts. I milled the end then I drilled and tapped the holes. The cover plate has a 1/2" thick plexiglass window. I turned a 1/2"wide x 1/4" deep rabbet joint on the edge and siliconed the window from the bottom of the cover plate. A rubber gasket seals the cover. I added a presta valve from a bicycle innertube and use a bicycle pump to pressureize the chamber. I also added a pressure guage.

 

[dave4868]

This is what I came up with.
I welded a plate on the bottom of a piece of pipe. I then welded some square stock on the outside for the cover plate bolts. I milled the end then I drilled and tapped the holes. The cover plate has a 1/2" thick plexiglass window. I turned a 1/2"wide x 1/4" deep rabbet joint on the edge and siliconed the window from the bottom of the cover plate. A rubber gasket seals the cover. I added a presta valve from a bicycle innertube and use a bicycle pump to pressureize the chamber. I also added a pressure guage.

Nice job! Thanks for posting the pics!

Is that pipe about 8" in diameter?

Dave C

 

[superstar]

The pipe is 6 1/2" i.d. and 1/4" thick wall.