Building a Pressure Tester with Sharkbite

Marvin007

I have built a 1/2” pressure tester with sharkbite. I have it connected to a straight piece of pex 300ft room temperature. I have tried it with a few different 300ft straight pex loops.

I have put air in the pex at 100 psi. After 6 hours I have lost about 7 PSI from my current loop. I have use tape and pipe dope on the metal fittings not the sharkbite connector. I have also put soap water on the connections but have not noticed any bubbles forming.

Does sharkbite seal correctly with 100PSI of air or should I expect problems?

Here is a picture of my connections.

EdTheHeaterMan

Air temperature change may account for 7 PSI change. I bet if the tube is placed in the sun, the pressure would increase.

Gsmith

Try repressurizing to 100 psi then observe for about 24 hrs. As above, air temp change and slight relaxing of the Pex on initial pressurization my account for your initial loss.

hot_rod

If you pump air with a compressor the air is warm or hit. As it cools you could lose some pressure. Put the whole test set up in bucket  of water to find any small leaks. The air valve itself could be leaking 

hot_rod

If I were to build a reusable tester I would use the Nibco Wrot Racer fitting. The release collar is much, much easier to release. No need to use that cheesy plastic release tool. Or hammer a channelick against the ring🤓
And they claim it is a reusable connection. I don’t think SharkBite are intended to be reusable

mattmia2

let's see p1/p2 = t1/t2
let's say it is 20c and falls to 0c
114 psia/p2 = 293k/273k
p2 = 106 psia ~= 92 psig

so it if falls from 70 f to 32 f your change in pressure is plausible. if it is in conditioned space you have a leak.

ethicalpaul

Pex stretch

ratio

Does it stop dropping after a while? When I'm pressure testing, I'll top it off once it twice during the first few minutes/half an hour—but I usually leave it under pressure for at least a day, often longer.

PC7060

hot_rod said:

If you pump air with a compressor the air is warm or hit. As it cools you could lose some pressure. Put the whole test set up in bucket  of water to find any small leaks. The air valve itself could be leaking 

Agree, I learned the hard way 30 years ago that gauges leak!

Marvin007

hot_rod said:

If you pump air with a compressor the air is warm or hit. As it cools you could lose some pressure. Put the whole test set up in bucket  of water to find any small leaks. The air valve itself could be leaking 

The valve in the valve stem was leaking. I have since started over with a new valve stem and used a 6” long piece of 1/2” aquapex wih a plug in the end and 2 cinch clamps. I have tested it in a bucket of water no air bubbles forming that I can see. Once I can get it to have a somewhat stable psi (as expected over 24hours or so) I will know my pressure tester works. Is 50 or 60 psi using air ok or should I be testing at 100 psi? This is for radiant loops.


I am still testing to see if I have a tiny leak over a 24 hour period.

hot_rod

Never hurts to put a cap on the valve stem after you pump it up. The tube and fittings can certainly handle 100 psi.

It’s hard for any size leak to hide from 100 psi🧐

mattmia2

You can put a piece of tape on there and make 3 marks, one at the needle, and 2 at 2 of the marks on the scale and can tell very precisely if the position of the needle changed. Sort of a poor man's mirrored scale.