Results 27 to 39 of 103
10-18-2009, 01:14 AM #27
10-18-2009, 01:22 AM #28
10-18-2009, 01:31 AM #29
Its late Saturday night I'm visiting with my buddy Weiser. Are messing with me?
A bottle of refrigerant open on a liquid line I don't think you will be in a vacuum if done right.
10-18-2009, 01:59 AM #30
10-18-2009, 02:04 AM #31Professional Member
- Join Date
- Oct 2007
Thanks for all of the help so far. I am majorly confused over the Sporlan info on charging. I have tried my best to understand how to apply the information and the table 2. I don't know if the design temp is the evaporator design temp or the anticipated outside ambient that is being referred to?
If anyone can make sense out of how it works please take this scenario and please tell me how to make sense out of the Sporlan data tables.
Here is the scenario:
Walk in freezer that has -20 cooling capability.
The system is charged with an outside ambient of 60 degrees and the sight glass has cleared and stabalized.Non unloading compressor.
Now say that I want to make sure that the charge for the headmaster is correct for the upcoming cold weather which could be as low as 20 degrees.
What data on table 2 do I use to determine the extra charge needed?
10-18-2009, 06:48 AM #32Professional Member
- Join Date
- Mar 2008
As was stated earlier, close the king valve ( outlet of the receiver ) and charge liquid into the liquid line supplying the TX Valve. If that is not an option charge liquid in the suction line as far away from the compressor as possible ( usually at the evaporator coil ) I close the hand valve at the case and meter liquid in the suction slowly.
In the case of shutting the condensor fan off, I have only used this method to empty the system quickly into reclaim cylinder at low ambiant conditions, shut off bypass and cycle compressor building discharge pressure to force liquid out of receiver.
10-18-2009, 10:25 AM #33Banned
- Join Date
- Dec 2006
- Middle Tennessee
10-18-2009, 10:53 AM #34
When initially charging ANY system, after drawing the vacuum down to the proper micron level, I charge as much as I can into the liquid line, until the flow out of the charging cylinder pretty much stops. Then, I start the compressor and begin metering refrigerant into the suction side.
I've never tried to close a valve between the compressor and the point where I am adding refrigerant into a liquid line. I would imagine you can't do this for long before the pressure in the receiver gets too high.
I'd like to hear more about it, though.
10-18-2009, 12:17 PM #35
10-18-2009, 12:19 PM #36
Type of refrigerant.
Number and size of return bends on the condenser (remember to EXCLUDE any subcooling coils)
Length of the condenser tubes.
type of refrigerant.
Given that data and a few minutes and I wil give you the flooding charge.
10-18-2009, 12:21 PM #37
10-18-2009, 12:40 PM #38
Now, with an ambient below 70, you need to be extra careful with this as it is fairly easy to overcharge. At an ambient of 60, it might not be too bad, but get down colder, and you can put an awful lot of gas into the unit.
At 60, you have already flooded part of the condenser, so you have to figure THAT amount out and also the total flooding charge out.
total flooding charge of say 8.5# (to flood from 70 degree ambient.)
At 60 degrees (use 60 as minimum ambient) your flooding charge is let's say 2#.
8.5# (total flooding charge) - 2# (amount ALREADY added) = 6.5# (amount left to add)
Clear as mud?
10-18-2009, 05:20 PM #39
On a more serious side, I have seen a very experienced refrigeration man "turn the bottle over" into the suction side and in a flash 10 lbs liquid straight to compressor. We were out in a week or 2 replacing the reed valves. He's getting old and I think he just screwed up due to his age.
And yes I am speaking from experience-albeit limited-and I understand the gap between theory and what real experience has to say about it.