R410a pressure testing

[djwilson77]

We have been queried on the pressure testing we do on R410a AC.

Any feed back appreciated on this one please 😃

We strength test at 43 bar (1.3 x MWP) for 15 minutes and leak test at 37 bar (1.1 x MWP), always have done. This is ok isn’t it? Its never been a problem before.

There’s been a couple of coils leak when we’ve tested AHU coils once installation has been completed but I’m sure the coils are at fault as the pressure was dropping at 20 bar.

[al]

Coil should be rated for 410a, did you check the plate for its rating? I've no issue testing split indoors to those pressures but on ahu coils i go max 30b, if they leak at 20b then it suggest a weakness in the coil.

[djwilson77]

Hi, thanks for the reply.

Found out the coils are tested to 33 bar only. They are used in reverse cycle as well.

What about strength test pressure? I assumed that it would be capable of that too? We do all of our VRV and splits to strength and then leak test pressures. Surely it should be the same?

We only done 20 bar on this particular one when we found the leak but would have carried out our normal testing. Leak on one of the elbows/passes on the coil.

[al]

Strength test is generally only on interconnecting pipe work, but unless you've valves fitted to isolate coil probably best to just test to leak test pressure and hold.

[ed00s]

Strength test is generally only on interconnecting pipe work, but unless you've valves fitted to isolate coil probably best to just test to leak test pressure and hold.

I agree but there is more, if system is new i was learned to leave separate all pipes with pressure up to 55 Celsius degree for minimum 1 hour/ big system for minimum 24 h .
But what my bos told me ( when i was working in Poland ) 1 rule is
RTFM, then labels and at the end rules like condenser 55 evap 45 water evap 45 * there is condensers for R134a they can reach 75 - 80 degree still RTFM)

In existing systems start from 2 bar then 5 and what manufacturers/labels/55 say.
Once my bos ask 2 installers to check 1 mitsi electric to check where is leak, they spend 5 days and i help them to deduce ( i told them to split pipework/indoor units in second day from condenser and dont disconnect gauges) ...the use UV dye but they did that wrong and whole condenser was gloving :P
After they left i did pressure test and nothing ..... i remove whole coil and put in plastic container and find little burbling in manufacturing joints. After remove from water i spray on this place .. and nothing, when i drop pressure to 1 bar its start bubbling ....
We lost 14 kg refrigerant in 7 days, mitsi send new coil its still working :F
find leak sometimes is just headache...
I have good for learning book in PDF if some is interesting its 4 th edition .
For the Horde