Nitrogen present in a system

[Koopy]

What wOuld be the expected charateristics of a air cooled system on r22 if it were to have a nitrogen mix inside. High head pressure obviously but liquid line temps subcooling superheats etc?
Say 24c ambient for arguments sake fully loaded chiller 10.2c suPply chilled water 12c return.

[SkyWalker]

well as the nitrogen distorts the pressure temp relationship, the pressure in the condenser increases without temperature so you would be reading high "sub cooling" for sure

[Tesla]

Hi Koopy
One way of testing this is to close the liquid line either valve or remove the solanoid don't forget to put a fat screw driver or bolt in the coil to stop it from burning. Then pump down the circuit. Manual on the condenser fans to cool the refrigerant to ambient. Then compare press and temp of refrigerant with PT chart. I would expect around 1700kPa Hp and around 480kPa Lp for normal operation depending on the load. Symptoms for noncondensables are high Hp, high current draw for given load and of course insufficiant cooling. Is it a recip and what make? For the above test a direct measurement of the refrigerant is best - you can buy a superheat calculation kit from RES I think they are now located in Alexandria.
I would imagine low subcooling and possibly high superheat.
The SH would depend on if there is a receiver or critical charge and how it got there in the first place. What are your suspicions on how it got there?
To remove it I used to pump down and blow of from top of condenser into a big cylinder of course. Depending on how much in in there if you confirm that is the problem. You could pump out most of the refrigerant with the chiller compressors into large cylinders and reclaim the rest then vac system. Then blow off from the top of the cylinders into another empty large cylinder allowing gas to settle each time and repeat a few times until the gas reads right on a PT chart. Then recharge chiller and weigh the gas as a check measure - but personally I charge by SH and SC, load and current.

[Gary]

Since air is about 80% nitrogen, I would expect the symptoms would be the same as air in the system.

[Magoo]

Well put Gary. definite non-condensibles in the system

[Koopy]

My suspicious arise due to the adjoining circuit being recently leak tested and before this there were no issues. I suspect the leak to be coming from the Evap end plate. One of the coolers where liquid/vapour and suction lines of both water and leave the one end of the cooler. I reckon the gasket division on the end plate has leaked during the pressure test. Never the less it will be interesting. I was confident about the mixture was just putting the question out there to hear what every one else has experienced. Cheers for the help guys.

[Fidge]

I had this in a toshiba multi system. Reclaimed all refrigerant into a large reclaim cylinder and let settle for about 20-30 minutes. As tesla said blew off from vapor into a vacced out small reclaimed cylinder and put on a new suction line drier just in case. Never had a problem since. Good luck

[Roger Hatt]

Hi I have had this problem a couple of times this year it seems to be more of a problem in the colder weather for some reason? however the symptoms are similar to air in the system, switch off the system and let the pressures settle out, using a pt chart you can determine the amount of non-condensables in the system even though the system may have been running for some time in this condition don't rule out some OFN in the system.
Conclusion: recover and vac recharge with new gas.

[jatinder.bharga]

i think compressor 'll blast.. it happened here on one hotel site during servicing the unit.. technician was checking leaks by charging nitrogen in R22 system at about 400 psi... suddenly somebody from the hotel room put the indoor unit on & comp started,, then blasted immediately.. Both technicians found dead on the spot. NITROGEN

[monkey spanners]

i think compressor 'll blast.. it happened here on one hotel site during servicing the unit.. technician was checking leaks by charging nitrogen in R22 system at about 400 psi... suddenly somebody from the hotel room put the indoor unit on & comp started,, then blasted immediately.. Both technicians found dead on the spot. NITROGEN

This is why systems should be electrically locked out and all non technical people removed from the area that pressure testing is taking place at.

[Gary]

i think compressor 'll blast.. it happened here on one hotel site during servicing the unit.. technician was checking leaks by charging nitrogen in R22 system at about 400 psi... suddenly somebody from the hotel room put the indoor unit on & comp started,, then blasted immediately.. Both technicians found dead on the spot. NITROGEN

I'm betting someone filled the nitrogen bottle with oxygen.