Pressure Loss during a Hydro test.

[steakman911]

thread404-318773

I was looking for some good info on chart recorders and came across this thread. i find it interesting that this fellow was losing 2% of his pressure during the test. Aside from the obvious, leaks, no one mentioned or asked about whether there was the possibility of any air trapped in said system or entrained in the test media while filling.

If I was losing pressure on a regular basis after trying the same test more than a couple of times, I would think that somewhere, somehow air was trapped in the system...no? Theres a reason Hi point vents are incorporated into piping systems...as are drains.

just a thought..

Cheers,

stk

 

[racookpe1978]

Volume of assumed air trapped is meaningless unless you are going to ALSO tell the observer whether ambient temperature rose or fell during the hydrotest. Further, if the hydrotest ran during "any" period of direct sunshine, the simple presence or absence of direct sunshine on the tank, pipes, or area might - or might not - be important!

However, you imply that having air inside the pipe might "increase" the pressure rise (hide the loss of fluid, reduce the measured pressure drop - however you want to phrase the situation.)

False!

A "solid system" - and I have run many hundred hours of solid system reactor and power plant systems with no air bubble or steam bubble! - is much, much faster at responding to ambient temperature, fluid loss, fluid gain, or even room temperature changes than a solid piping system with even a few cubic inches of water vapor or compressed air.