refrigerant quantity

[bob gibson]

how do you determine a refrigerant charge for a system that is customized by using the pressure readings and sight glass.it is a york 209 and needs from 500 rpm and up

[Forum Tech]

"Bob,That sized compressor is probably using a TXV. Systems using a TXV require a liquid refrigerant receiver. The maximum correct charge will be 80% of the receiver capacity. The pressure readings are useless for determining a proper charge. The sight glass appearance may be different, depending on the refrigerant used. What refrigerant are you using? Forum Tech"

[bob gibson]

will be using r134.The evaporator and compressor were taken out of an older rv van which had an after market ac system installed with no stickers stating its charge.The evaporator looks very similar to a danhard unit of about 16000 btu rating.I put this system together on a work bench powered by a 3/4 hp electric motor and compressor reving at 600 rpm.the shop temp was around 65f.i was getting 20-30 psi low side and 100-110 psi high side.The clutch was just wired on all the time so it wasnt cycling.outlet temp was 38f.This is going to sound like a stupid question but what is a liquid refrigerant receiver.yes it does have a txv .thanks in advance for your assistance.I have been doing automotive ac work for 30 years but never delt with one that didnt have some way of knowing the recommended charge.Also any idea of the btu rating i could achieve?

[bob gibson]

If by liquid refrigerant receiver do you mean the receiver dryer?If so this one is approx 3in x 7in.