Heated R134A ??

[craigpcg]

afternoon ppl, I used to work for a large refrigeration company in edinburgh b4 i start my own company but i have a question that id like to ask.

a few years ago i was at job were the condensor fan motor was faulty causing the system to run EXTEREMLY hot, gas used was R134A. Now the question i ask is after i replaced the fan motor, i place my gauges on to find that system appeared to be short of gas. pressure tested system with ofn to find no leak what so ever.

now id put it down to the R134A being heated up that much that it had lost its propertes in which it is made up from causing to appear short of gas.

sooooo i had a little talk with my service manager and he basically laff at me but to this day the system has never lost its gas (as i now have the customer ;) ) and works perfect.

iv i just lost the plot or am i right???

[Brian_UK]

I would have to ask - how much gas did you take out of the system and how much did you put back in after pressure testing?

[chillin out]

Also, did you happen to change the (blocked) drier at the same time??

Chillin:):)

[Pooh]

R134A is a pure refrigerant and does not lose its properties, ot is either there or it has escaped. There may have been a leak as pressure testing with OFN when using R134A is a waste of time as iits molecular size is approximately one tenth of that of OFN, you should have used helium which has a similar molecular size.

Ian

[Peter]

[QUOTE=Pooh;81584]pressure testing with OFN when using R134A is a waste of time as iits molecular size is approximately one tenth of that of OFN, you should have used helium which has a similar molecular size.

QUOTE]

Ian,
Sorry mate 134a molecule is not the same size as helium and is also larger than OFN.

[Grizzly]

afternoon ppl, I used to work for a large refrigeration company in edinburgh b4 i start my own company but i have a question that id like to ask.

a few years ago i was at job were the condensor fan motor was faulty causing the system to run EXTEREMLY hot, gas used was R134A. Now the question i ask is after i replaced the fan motor, i place my gauges on to find that system appeared to be short of gas. pressure tested system with ofn to find no leak what so ever.

now id put it down to the R134A being heated up that much that it had lost its propertes in which it is made up from causing to appear short of gas.

sooooo i had a little talk with my service manager and he basically laff at me but to this day the system has never lost its gas (as i now have the customer ;) ) and works perfect.

iv i just lost the plot or am i right???
Craig.
Could it not just be that when you replaced the condenser fan.
The unit condenced more efficiently, lowering the liquid line and suction pressures.
Fundermental mistake to assume low suction pressure means gas shortage.
I can only assume that you were refering to a lower suction pressure when using your gauges to diagnose a refrigerant shortage?? Or have I missed something?
Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif

[Plank!]

Ian,
Sorry mate 134a molecule is not the same size as helium and is also larger than OFN.[/quote]

Can you back this up with a reference ?

I've always been shown that R134a has a much smaller molecule size, hence we use a 10% helium/nitrogen mix for pressure testing.

[Peter]

Nitrogen or OFN is a much smaller molecule than refrigerants which is one of the reasons it is used for leak testing.
Helium is a smaller molecule than Nitrogen hence a 10% Helium /Nitrogen mixture will find smaller leaks than just OFN. It has nothing to do with the size of the 134a molecule. In fact water is a smaller molecule than 134a which is well documented in filter drier literature.