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jwasir
30-09-2007, 12:35 AM
Hi,

I am curious to know, why liquid line sight glass start to bubble with kind of white foam during unlading of 1 bank of semi hermetic compressor.

Compressor is 40 HP Copeland compressor. Operating conditions are 25/110F.

Thanks in advance.

BigJon3475
30-09-2007, 12:50 AM
Sounds like liquid slugging from being overcharged or having liquid return back through the compressor.

jwasir
30-09-2007, 02:43 AM
Thanks BigJon,

The foam or bubbles goes away as soon as system unloading is over.

And the Superheat at the compressor is approx 10 deg.

Do U still think, if this is the case of slugging?

BigJon3475
30-09-2007, 05:03 AM
Thanks BigJon,

The foam or bubbles goes away as soon as system unloading is over.

And the Superheat at the compressor is approx 10 deg.

Do U still think, if this is the case of slugging?


What's the amp draw like during startup?

NH3LVR
30-09-2007, 06:31 AM
Hi,

I am curious to know, why liquid line sight glass start to bubble with kind of white foam during unlading of 1 bank of semi hermetic compressor.Thanks in advance.

If it is the LIQUID LINE Sight Glass foaming,that is not an indication of slugging.
My first thought would be that this is a because of a sudden drop of Head Pressure when the compressor unloads.
You can verify this with your guages.

Pooh
30-09-2007, 02:50 PM
NH3LVR
that sounds about right also the suction pressure will come up reducing the pressure differential across the metering device thus reducing flow. Without more information it is difficult to give more advice.

Ian

750 Valve
01-10-2007, 01:53 PM
This is most likely the liquid in the liquid line reaching its flash point, try increasing your subcooling so when you unload the affect is less - although I think its got to do with mass flow rates too and line sizing, I only ever see it on single systems with one liquid line, racks with headers don't tend to see this.

jwasir
02-10-2007, 10:22 PM
Thanks to all for the nice explanation.

John Hunter
04-10-2007, 05:39 AM
Hi,

I am curious to know, why liquid line sight glass start to bubble with kind of white foam during unlading of 1 bank of semi hermetic compressor.

Compressor is 40 HP Copeland compressor. Operating conditions are 25/110F.

Thanks in advance.
Hi jwasir.
What is the refrigerant R22??. Could be oil problem .
JH

jwasir
05-10-2007, 03:17 PM
Hi jwasir.
What is the refrigerant R22??. Could be oil problem .
JH

The Refrigerant is R-22.

I tried to increase the sub cooling , as advised by one member.

This didn't solved the problem completely.

The system is complete with Low ambient package and Hot gas By-pass.

The head pressure is maintained at 225 PSI by dumping hot gas in the receiver and also the HG by-pass is always on to maintain the min required suction pressure of 55 PSI.

Now while charging, LL sight glass get almost clear but again starts to bubble in few minutes.

The subcooling before the receiver is approx 30F and after the receiver is 10F.

The comp. is 40 HP copeland with 2 unloaders. When 2 bank unloads the sight glass gets worst and less than half glass can be seen with kind of white fluid flowing in it.

When both cylinders are loaded, the sight glass gets nice and clear.

Does the system needs more ref. How much?

philjd26
08-10-2007, 07:22 PM
hi jwair, best way to charge your system is make sure ther is a good load on evaporator,possibly do a cuircut at a time.........also you bubbling problem sounds like you cant really help as you are dumping from the recever as you say which is liquid and by opening the by pass and exposing the high side to this pressure drop, will cause some flashing to take place...it acts like a pmv by the sounds of it

rgrds phil

wineman
08-10-2007, 11:05 PM
turn the sight glass round so u cant see it then go to the pub

750 Valve
10-10-2007, 09:30 AM
turn the sight glass round so u cant see it then go to the pub

:D:D:D I like your style ;););)