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joe magee
13-01-2007, 08:34 PM
I recently started up a walkin freezer box. Receiver at 50%. temp in box is fine. How come the sight glass does not clear? 2 ton condensing unit 404a refrigerant suction @ 13 psi discharge at 200 psi no head master.Unit on top of box in a 70 ambient no restictions . This seems to fool a lot of techs They always want to clear the glass without torching the receiver ending up with an over charge.:)

chillin out
14-01-2007, 12:25 AM
I think it's something to do with the way it is piped. Liquid line oversized? or just the fact that the pipe is going straight down to the txv.

Just a thought.

Chillin:) :)

joe magee
14-01-2007, 01:53 AM
possibly. The company I work for has a large engineering department and they can't give me a good answer. Oh well. We also design and build racks for many of the large supermarket chains.
Cheers

Andy
14-01-2007, 02:35 AM
I recently started up a walkin freezer box. Receiver at 50%. temp in box is fine. How come the sight glass does not clear? 2 ton condensing unit 404a refrigerant suction @ 13 psi discharge at 200 psi no head master.Unit on top of box in a 70 ambient no restictions . This seems to fool a lot of techs They always want to clear the glass without torching the receiver ending up with an over charge.:)

flashing in the sightglass indicates a lack of subcooling, this maybe from and undercharge OR it is a restrictive liquid line causing a drop in pressure, flashing off the liquid partially to gas.

Alternatively the sightglass maybe too close to the expansion valve, showing the every opening of the valve:)

The techs should charge to a known weight or the subcooling off the condenser;)

Kind Regards Andy:)

Pooh
15-01-2007, 09:30 PM
I have had this sympton when a insufficiently sized receiver was fitted to a system the tubulance of the refrigerant entering the rceiver was causing bubbles in the outlet of the receiver showing in the sight glass. Fitted a larger receiver and the problem went away, took a bit of sorting out though.

Ian

hem057
16-01-2007, 04:12 AM
I remember reading too that with the 400 series refrigerants that the sight glass may not clear, due to the different components seperating and therefore a little vapor pressure shows up in the sight glass, therefore the danger of overcharging trying to clear the sight glass.