Fun with inconsistent gas tests results

[PlumbTired]

Good'ay
Wondering what I have been doing wrong or what I should be doing differently.

Have had some jobs lately where I will carry out a gas test on residential work and it will fail, I will isolate stove, hwu and any bayonet connections and still fail, I can do up to 6 testes on one job and have what appears to be a consistent drop.
But come back the next day with everything connected and will get a solid pass on all my tests.

I tend to use a digital Manometer, weather with be consistent and nothing will be heating or cooling any of the pipework. Rural so always LPG and hook up by disconnecting regulator and attaching a test nipple onto the flared cu pipe.

Any clues as to what I'm mucking up? because I have wasted more hours on gas leaks than I would like to admit

Cheers

 

[Deleted member 120897]

I don’t hold lpg qualifications, only advice I can offer is - check or replace your manometer hose.

 

[ShaunCorbs]

Also is pipework purged ?

 

[Deleted member 120897]

Also is pipework purged ?

Is that how they do it on lpg then?

 

[PETE 123]

Sunlight on pipes or depending on pipes contracting and expanding with heat will cause this sometimes.

 

[EvilDrPorkChop]

Air in Pipes, purge it through then test.

 

[PlumbTired]

I don’t hold lpg qualifications, only advice I can offer is - check or replace your manometer hose.

That's kind what I was hoping at one point, but hoses are sweet

 

[PlumbTired]

Also is pipework purged ?

Not completely with an inert gas no, it's always small residential houses,20m - 30m of cu pipe in total on the whole service, and do not know any plumbers around that do fully purge for testing.

How much of an effect would that have on my testing? More sensative to temperature fluctuations or?

 

[ShaunCorbs]

What happens with the figures do they just keep dropping eg 30-5mbar to 30-25-30-46 etc ?

 

[Knappers]

LPG does eat through hoses and I've lost some hours chasing nonexistent leaks.
Tried using black hose but seems to still leak.
Small volume, relaxing rubber hose, temp all have massive effects on pressure and it can be a bit of a nightmare at times.
Personally (and this really isn't right) If it's an awkward system to test I like to do at high pressure like 110mb and monitor for a prolonged period. If there's an issue you'll see it and can look for leaks but otherwise it may stabilise within 5 min and if it holds pressure (stays in a range) for 5 more then your good.

Believe it or not this does conform to a tightness test procedure for LPG, just prob not one specific to your situation, I'd say it exceeds the requirement and that's that

 

[PlumbTired]

What happens with the figures do they just keep dropping eg 30-5mbar to 30-25-30-46 etc ?

Working with KPA, start the test around 3.30kpa and it will generally drop .01 every 1-3 minutes

 

[PlumbTired]

LPG does eat through hoses and I've lost some hours chasing nonexistent leaks.
Tried using black hose but seems to still leak.
Small volume, relaxing rubber hose, temp all have massive effects on pressure and it can be a bit of a nightmare at times.
Personally (and this really isn't right) If it's an awkward system to test I like to do at high pressure like 110mb and monitor for a prolonged period. If there's an issue you'll see it and can look for leaks but otherwise it may stabilise within 5 min and if it holds pressure (stays in a range) for 5 more then your good.

Believe it or not this does conform to a tightness test procedure for LPG, just prob not one specific to your situation, I'd say it exceeds the requirement and that's that

I might look into getting new hoses even though I can't find a leak on them, and might have to start high-pressure testing more often, it's a bugger to disconnect every but what ever works at this point!
Cheers!

 

[ShaunCorbs]

Working with KPA, start the test around 3.30kpa and it will generally drop .01 every 1-3 minutes

Does it keep dropping or drops a lot and then rises ?

 

[Last Plumber]

Use a water gauge and get yourself a new rubber tube for it.
It is a lot more relaxing to use than some erratic digital readout.
No calibration certificate needed.
No batteries or charging to remember.