pressure testing

[bangoman]

hi all , In splits is it a gud thing to pressure system on service valve wen checkin for leaks.Is there n risk of passing nitrogen into the system if it exceeds the standing pressure of refigerant inside .Hw long does it take to break a vacuum assumin the system has a leak.

[Brian_UK]

It all depends on the quality of the valve. If you are unsure then it would be better to recover the refrigerant.


How long does it take to break a vacuum assuming the system has a leak.Sorry, don't understand this bit.

It takes a moment to break a vacuum but if there is a leak I wouldn't think there is going to be much vacuum anyway ;)

[Grizzly]

hi all , In splits is it a gud thing to pressure system on service valve wen checkin for leaks.Is there n risk of passing nitrogen into the system if it exceeds the standing pressure of refigerant inside .Hw long does it take to break a vacuum assumin the system has a leak.

Hi bangoman.
I don't know if it is politically correct.
But personally I never introduce nitrogen to a part charged system.
Because if you have a leaking valve and you cross contaminated the refrigerant, you have got a real problem.
If say you have pumped a system down and have worked on the de-pressurised side of the system.
Pull a deep vacuum on that side if you can pull one and it holds over a period of time.
Then it's likely that it's sound.
Break the vacuum with refrigerant by cracking the isolation valve (open and shut quickly).
Monitor the system pressure and leak check the work area!
And repeat until the system is back in balance, checking again once the system is back up and running.

Anyways that's how I do it, others may do it differently?

May I point out that Leak checking is not Pressure testing!
I don't mean to be rude but lot's of people refer to the fact that they are leak checking with nitrogen as Pressure testing.
When that is something totally different and most of us rarely have to do it!
If I have got completely the wrong end of the stick, then I apologise.
Because you could be asking about pressure testing newly installed pipework.
In which case it is safer to plug the 2 ends and test the pipework independently!
Cheers Grizzly

[dogma]

Hw long does it take to break a vacuum assumin the system has a leak.


extract from Australia and New Zealand refrigerant handling code of practice 2007 • Part 1 — Self-contained low charge systems

6 Evacuation
This section refers to evacuation in the field only – not evacuation during the manufacturing
process.
As the systems covered by this code are supplied pre-charged with refrigerant there is
no need to evacuate the system upon installation. If evacuation is required at a later stage,
however, the following procedure must be followed:
6.1 Instructions must be followed if the system manufacturer has supplied instructions
for evacuation, except where the instructions specify a practice that will lead to
emission of refrigerant.
6.2 The system must be evacuated to less than 117 Pa absolute (900 microns of mercury)if the system manufacturer has not supplied instructions with the system for
evacuation.
6.3 After the system has been evacuated the vacuum pump should be isolated from
the system. As a guide, with constant ambient conditions, the vacuum should not
rise more than 13 Pa (100 microns of mercury) in one hour. A greater rate of rise may
indicate a leak or the presence of moisture (see also 7.1.9).

[dogma]

..... and bangoman.... if you think there may be a risk of N2 pushing through the valve seat... then leave the bonnets on, put your guages on, check the system pressure. front seat the valves, take off the bonnets, blow out with a bit of N2 and use your digital leak detector to make sure the valves are sealed then charge the N2 into your pipes at slighty less pressure. leak test and away you go.. :)

[bangoman]

dogma,wot r bonnets ?

[dogma]

dogma,wot r bonnets ?


sorry mate... the copper/ tin caps under the flare nuts on the outdoor unit... Sometimes they are plastic caps