Help, pressure testing!!!!

[mutley racers]

hi there, Just need a little advice. Have been pressure testing some pipes today and seem to be having trouble with last run.

I pressure test them for 3 bar and then leave for 30 mins and see if they have dropped. The first 4 sets i tested were fine and did not trop over the period, but the last one seems to drop about half an PSI. Not sure if it is a PSI or not. But half on of one of the five digites that add upto 1 bar.

The thing is, i have went around with my washing up liquid to all my joints and cant find any leaks any where.

Even tightened up all the rad valves but it still drops this amount.

Is this ok? Or is it definately a leak?

Look forward to some advice.

Regards

Leroy

 

[migoplumber]

you need to do the drop test again, sometimes a drop could be down to air locks, repeat the test, if there is a drop however minimal and the air has been totally removed from the system then you have a leak somewhere.
toilet paper dry all your joints, repressurize on your test, leave for an hour, then toilet tissue paper all the joints. you'll find the leak if there is one!
good luck

 

[mutley racers]

hi, my test is with air

 

[migoplumber]

if your air test is showing a minute drop, that you cant find, advance to the wet test which will be easier to locate. make sure you have a good rapid drain off ready just in case

 

[justlead1]

Hi.Temperature drop has a big effect on air tests, also check testing apparatus, gauge etc. Air testing at those pressures can be dangerous it a joint pulls apart. Good Luck

 

[Plucky]

Hi.Temperature drop has a big effect on air tests, also check testing apparatus, gauge etc. Air testing at those pressures can be dangerous it a joint pulls apart. Good Luck

This is new to me, why is air testing at 3 bar dangerous?

We do our initial dry test on underfloor heating systems at 4.5bar

 

[justlead1]

Hi. Air can be compressed. Should for example a push fit plastic pipe pull out of a coupling, the effect could be like that of a balloon when the air is let out suddenly, it flies a round the room. Whether a small or large pipe it can have the same effect. Testing underfloor circuits with joints confined to a manifold and well fixed will reduce risk. (try it out under controlled conditions with a coil of plastic pipe) Water is virtually incompressible. So if the system to be tested is filled with water and trapped air released, when water is introduced to increase pressure on gauge via pump only a couple of pumps increases the pressure greatly (only adding say an egg cup full of water) in the event of a leak any thing more than an egg cup full and pressure is back to atmospheric. With air massive volumes are introduced into the system to increase the pressure and come out rapid in the case of a leak. Good Luck

 

[Plucky]

Hi. Air can be compressed. Should for example a push fit plastic pipe pull out of a coupling, the effect could be like that of a balloon when the air is let out suddenly, it flies a round the room. Whether a small or large pipe it can have the same effect. Testing underfloor circuits with joints confined to a manifold and well fixed will reduce risk. (try it out under controlled conditions with a coil of plastic pipe) Water is virtually incompressible. So if the system to be tested is filled with water and trapped air released, when water is introduced to increase pressure on gauge via pump only a couple of pumps increases the pressure greatly (only adding say an egg cup full of water) in the event of a leak any thing more than an egg cup full and pressure is back to atmospheric. With air massive volumes are introduced into the system to increase the pressure and come out rapid in the case of a leak. Good Luck

I see makes perfect sense. Something that I hadnt thought about but will now keep in mind.