OFN Cross contamination

[Argus]

There is an interesting problem that crops up from time to time.

EN 378 is quite specific on the subject of pipe work pressure testing using OFN.

However, there comes a time where pipes have to be pressurised on existing systems where the condensing unit or pack contains refrigerant, or even new systems that come with an operating charge. All that stands between the refrigerant and the high pressure OFN is often a quite basic service valve ? frequently the shut off rate is less than 100% and they let by.

Inevitably if the pipes are coupled when the pressure test and the drop test take place, some of the OFN enters and contaminates the system. This happens more often than people admit to, I think.

If the pipes are tested separately from the unit before coupling to the unit, the final joint to the service valves will not have been tested to the same integrity as the rest of the system.

The real answer, I know, is to remove the entire charge and to pressure test the whole system, but in the real world this isn?t going to happen?..is it?

Interested to hear your views
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