is this check valid for non condensables

[devlin maguire]

I am checking for non condensables in R22 balanced pressure on both guages is 8.9 Bar
@23C on the PT chart this corresponds to R22, I then put gauges on a bottle of reclaimed 22 at the same ambient and the gauges read 9 and a bit bar, can I now assume hat there are no NC's present, the PT's were taken at the compresser service valves which has been idle for 24 hours the ambient at the comp was 21.9C
Devlin

[Tesla]

Hi devlin
The above method is not acceptable for checking non condensables. Your reference is reclaimed refrigerant which could have non condensables or contaminants in it. Also the ambient temp is constantly changing.
The way to check it is to either pump down or reclaim the system refrigerant, measure accurately the temperature of the refrigerant and the pressure of the refrigerant then compare with a PT chart.

[stufus]

Tesla Virgin R22 is not available over here any more ! Only reclaimed or recycled .
Devlin ideally you need to recover a couple of kgs to a clean cylinder and check using a PT chart
Cheers
Stu

[devlin maguire]

Thanks guys just to clarify, the cylinder of 22 I have is newly purchased recycled 22 that I got to top up this system, and, it is this I used as a base line and refered to the R22 PT chart, the figures there obtained were compared to the system charge pressure as read from the gauges and as in my original query, the results from the bottle of "new" R22
and those from the system gauges are as close to identical as you can get so in conclusion system PT and Bottle PT are the same wouls that then not indicate a NC free system
Dev

[mikeref]

Devlin, i would have thought that standing pressure and temperature could only give guidance to "type" of refrigerant. Non condensibles, depending on percentage of refrigerant charge, will hang around the highest point of the system doing nothing untill refrigerant is circulating, then causing havoc to system pressures.. Mike.

[devlin maguire]

My understanding is that in a balanced system IE standing idle with high and low sides at equal pressure and at a given ambient and a known refrigerant, R22 in this case, any NC's present will alter this PT regardless of where the NC's are hiding as they will affect absolute pressure due to the fact of their prescence and the more knowledgeable of chemistry can in fact tell what those NC's are although that may be speculative, my reasoning is if a bottle of "clean" R22 gives the same results as the system in the same location and ambient then there is no NC's present,
Devlin
PS found this which would indicate I am on the right track 2nd page
http://www.refrigerants.com/pdf/NRInews-Smr11.pdf

[TRASH101]

Dev unless you can be sure that the temp of all the major refrigerant holding components are the same(ish) your results are a guess at best especially if there is no saturated vapor present, as a gas will take a sensible heat gain with no significant rise in pressure.

Best practice is to pump down into the condenser and leave the fan running on the condenser until you can be confident that the refrigerant is at ambient temp.

[Tesla]

Hi devlin
It clearly states to isolate refrigerant in the condenser (unless I read page 2 wrongly) which would indicate that you are incorrect. Please reread your reference on page 2 and point out where it states your method is accepted or admit you have misinterpreted this information. The ambient temperature is constantly changing and the temperature of the refrigerant in a container could be different to the temperature of refrigerant in a condenser.
At the end of the day the only way to do the test is with accurate measurement of the refrigerant temperature and accurate measurement of the pressure of the refrigerant isolated in the condenser or where the whole charge has been reclaimed into a container. There must also be liquid refrigerant present. These values are then compared to a PT chart and where a few PSI difference is measured there are non condensables present in the system.

[devlin maguire]

Hi guys, fair point(s) I may have mis read or interpretated it wrongly, although I still maintain that if I have identical figures for both system and known NC free samples at the same ambient same location then that wouls indicate a NC free system,However I will today extract 4 Kilo of gas from the system and recheck, it is not feasable to pump down the system or run fans mainley due to time constraints today, thanks for your input it is very much appreciated
PS would'nt the sight glass indicate moisture ?
Dev