Pressure test failure?

[Sammy0815]

Hi guys,

I am a little worried about my plumbing at my pool that is almost done, except for plaster.
After all equipment was hooked up, we are doing a second pressure test with air.
I have simple pool plumbing setup with 1 pump, 1 filter and 8 on/off valves connected with all lines at the pool with glued on end caps.
So they (air) pressurized the system with 21 PSI and now 2 days later I am at 15PSI.
Is my system ok or not?

 

[Bperry]

Hi guys,

I am a little worried about my plumbing at my pool that is almost done, except for plaster.
After all equipment was hooked up, we are doing a second pressure test with air.
I have simple pool plumbing setup with 1 pump, 1 filter and 8 on/off valves connected with all lines at the pool with glued on end caps.
So they (air) pressurized the system with 21 PSI and now 2 days later I am at 15PSI.
Is my system ok or not?

Why are they doing a pressure test now?

 

[ajw22]

Did the temperature change between pressurizing the system and 2 days later?

It is better to pressurize a system with water. The pressure does not change with temperature and you can see the wetness where a leak is.

 

[mas985]

So they (air) pressurized the system with 21 PSI and now 2 days later I am at 15PSI.

That is about 17% decrease in absolute pressure 35.7 PSIa to 29.7 PSIa. So according to the gas law, absolute temperature and pressure are directly proportional, therefore air temperature would need to decrease 17% on an absolute scale which would be over 85F drop in temperature. I don't think that amount of pressure change is due to just air temperature.

Is my system ok or not?

Doesn't seem to be ok. Pressurizing with water would make it a little easier to detect a leak if it isn't buried yet.

 

[Sammy0815]

Well they first pressurized it without the equipment with water, and everything seemed to be ok.
Now, a couple of weeks later with the pool almost done and equipment hooked up, they pressurized it again with air.
And in regards to the temp: Yes, it dropped from 60 to 32, but I also think that wouldnt explain such a huge drop in pressure.

So I am a little worried what the problem could be...

I guess wait for the freeze to be over and then pressurize with water again?

 

[Bperry]

Well they first pressurized it without the equipment with water, and everything seemed to be ok.
Now, a couple of weeks later with the pool almost done and equipment hooked up, they pressurized it again with air.
And in regards to the temp: Yes, it dropped from 60 to 32, but I also think that wouldnt explain such a huge drop in pressure.

So I am a little worried what the problem could be...

I guess wait for the freeze to be over and then pressurize with water again?

I’m not understanding why they would do a second pressure test when it would be impossible to fix anything that was underground and buried under concrete. Unless something was changed or had an accident that they suspect that the system was damaged and needed another pressure test.

 

[JoyfulNoise]

If it passed its water pressure testing before the equipment was installed, then it's most likely fine. From a practical standpoint, it is very very difficult to get pool equipment to be be "air tight". All it takes is for one gasket to be slightly misaligned or something like the multiport valve to be slightly off, and pressurized air will leak way more easily than water will. Air is also a lot more compressible than water so it doesn't really make for a good test in this context.

My guess is if you removed all the equipment and manifolded all the pipes back together and did an actual water pressure test, you'd get the same results you got last time.

 

[Sammy0815]

I’m not understanding why they would do a second pressure test when it would be impossible to fix anything that was underground and buried under concrete. Unless something was changed or had an accident that they suspect that the system was damaged and needed another pressure test.

Yesno... there was a small accident that was repaired and then we realized that we never tested the system with all the equipment hooked up.

If it passed its water pressure testing before the equipment was installed, then it's most likely fine. From a practical standpoint, it is very very difficult to get pool equipment to be be "air tight". All it takes is for one gasket to be slightly misaligned or something like the multiport valve to be slightly off, and pressurized air will leak way more easily than water will. Air is also a lot more compressible than water so it doesn't really make for a good test in this context.

My guess is if you removed all the equipment and manifolded all the pipes back together and did an actual water pressure test, you'd get the same results you got last time.

Thats kinda what I was thinking/hoping, that the equipment is not 100% airtight cause its mostly screwed on and not glued on.

 

[FloatOnFrank]

A drop from 21 PSI to 15 PSI could mean a minor leak or air loss, but it might also be normal due to temperature changes. Double-check all fittings and caps just to be sure.