Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
(OP)
All;
As an AHJ/Owner's Rep, we get called to accept new sprinkler installations. From time to time, we have installers that will fill the new system, then immediately pump the system up to 200+ psi, and allow the water to heat up in the South Texas sun. At the end of the two hour test, our pressure has risen (both due to the coefficient of expansion of the water and the dissolution of air due to increased temperature).
We can't tell from a pressure rise whether there are no leaks - the system might have a bleeder that lets 2 psi off, but the system temp creates a 7 psi gain, or it might be tight and the system temp has created a 5 psi gain. Since we can't tell, we reject the test. However, the result is "no pressure loss," which meets the letter of the code.
We prefer that they allow the water to temper for 24+ hours, but this doesn't always happen.
We can model temperature effect on pneumatic systems pretty well by applying PV=nRT, but hydrostaic testing is a little more finicky. How do you, my fellow AHJs, react to pressure gains on hydrostatic tests?
As an AHJ/Owner's Rep, we get called to accept new sprinkler installations. From time to time, we have installers that will fill the new system, then immediately pump the system up to 200+ psi, and allow the water to heat up in the South Texas sun. At the end of the two hour test, our pressure has risen (both due to the coefficient of expansion of the water and the dissolution of air due to increased temperature).
We can't tell from a pressure rise whether there are no leaks - the system might have a bleeder that lets 2 psi off, but the system temp creates a 7 psi gain, or it might be tight and the system temp has created a 5 psi gain. Since we can't tell, we reject the test. However, the result is "no pressure loss," which meets the letter of the code.
We prefer that they allow the water to temper for 24+ hours, but this doesn't always happen.
We can model temperature effect on pneumatic systems pretty well by applying PV=nRT, but hydrostaic testing is a little more finicky. How do you, my fellow AHJs, react to pressure gains on hydrostatic tests?





RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
Especially if you can see most of the pipe and heads
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
would stick with two hour test even if you can see every inch of pipe
have not found an inspector that sets at a gage for two hours, some like to mark it and come back, now depends on the building, if it is going to take two hours to walk the entire buidling, than they can do that while the pressure sets.
It is better to have a problem during the test than in the future during a fire, or failure for some other reason.
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
So from the rule point of view if you cannot see all the joints, this "OR" means if the gauge keeps above the test pressure it is OK.
I think that if it does not leak and the pressure is above the 200#, it does not matter what happens inside the pipe.
All the test may behave different and ideally it is better to specify to the contractor what sections shall be visually inspected for leaks and what sections may be witnessed just by the gauge reading.
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
RE: Fire Sprinkler acceptance testing: Pressure rise during 200 psi hydrostatic test
jdelahunt
the attached link explain the relationship between Density of Fluids - Changing Pressure and Temperature
i hope it help.