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zetreque » Thu Nov 13, 2014 7:12 pm wrote:I'll check them out. Pretty sure it's going to be pricey though.
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CanadysPeak » Thu Nov 13, 2014 5:11 pm wrote:zetreque » Thu Nov 13, 2014 7:12 pm wrote:I'll check them out. Pretty sure it's going to be pricey though.
Any inexpensive pressure gauge will give psig rather than psia. You could always use a reference pressure and 2 cheap gauges. You can get pretty inexpensive gauges off old pressure washers - they go up to 1800 psi or above. You can make a simple reference with a 1 atm cast iron sphere, like a Magdeburg sphere except clamped shut.
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zetreque » Thu Nov 13, 2014 11:36 pm wrote:CanadysPeak » Thu Nov 13, 2014 5:11 pm wrote:zetreque » Thu Nov 13, 2014 7:12 pm wrote:I'll check them out. Pretty sure it's going to be pricey though.
Any inexpensive pressure gauge will give psig rather than psia. You could always use a reference pressure and 2 cheap gauges. You can get pretty inexpensive gauges off old pressure washers - they go up to 1800 psi or above. You can make a simple reference with a 1 atm cast iron sphere, like a Magdeburg sphere except clamped shut.
Not sure I understand. The gauge is submersed in water so the needle side is open to the water environment, and the liquid side is sealed to the iron sphere? A pressure washer gauge would be opposite. The hose side is connected to the fluid/liquid and the gauge side is open to the atmosphere.
Actually, it doesn't matter if the pressure is acurate at all. I just need to be able to tell an increase in pressure as depth increases, and it needs to be able to read up to about 900 PSI
How well would it work if I did something like encase the needle atmosphere side inside a clear acrylic epoxy or something and just left the liquid side open to the water?
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zetreque » Fri Nov 14, 2014 10:50 am wrote:In the past, I've not been able to find one that ranges up to that high of pressure, additionally being able to waterproof it....
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zetreque » Fri Nov 14, 2014 3:17 pm wrote:I thought I gave plenty of information for my task.
Looking for cheap method to read pressure under water up to 1000psi (lets go with that nice round number instead).
Does it help if I say to pretend it is a scuba diver that wants to read a change in pressure up to 1000psi? And the scuba diver is not close enough to the surface to connect any sort of hose to the atmosphere.
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zetreque » Fri Nov 14, 2014 5:31 pm wrote:Thanks Dave,
I wonder though for that gauge. If you were to drop it in the ocean, and it sunk to a depth of ~2000 feet, would it still function since it was designed to work in the atmosphere and not underwater?
I'm imagining that if you took any ordinary gauge and put it deep down into water, the pressure is just going to be equal on both sides of the "diaphragm" at any depth. Correct me if I am wrong, but gauges like that work by starting out with the same pressure in two spaces (the atmosphere, and the container) and then changing the pressure of one space, and the gauge reads the difference of pressure.
If that thinking is correct.
One idea I just had this morning was to take a gauge like that and attach it to a metal sphere. Charge that sphere up to a pressure of the gauge (1000psi) then as your gauge sphere combination sink into the water, the increase in water pressure is going to push the pressure back down, and you would able to read pressure, just in reverse.
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Dave_Oblad » Fri Nov 14, 2014 2:40 pm wrote:Aw Haw..
So you are reading the differential pressure between inside something and outside something?
Anyway, the specs should explain that.. but as you say, you can seal one side at standard pressure and it will display the difference between the sealed section and the high pressure side.
CP is correct.. but a Scuba tank is rated from 3000 to 4000 PSI, and they also have Gauges for charging them.
Regards,
Dave :^)
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Dave_Oblad » Fri Nov 14, 2014 5:40 pm wrote:Aw Haw..
So you are reading the differential pressure between inside something and outside something?
Anyway, the specs should explain that.. but as you say, you can seal one side at standard pressure and it will display the difference between the sealed section and the high pressure side.
CP is correct.. but a Scuba tank is rated from 3000 to 4000 PSI, and they also have Gauges for charging them.
Some more (not too expensive) stand-alone Gauges:
http://www.ebay.com/bhp/scuba-tank-pressure-gauge
Regards,
Dave :^)
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