Results 1 to 20 of 20
Thread: Charging by weight
-
30-12-2010, 10:47 PM #1
Charging by weight
Hi ive come across some machines that specify that the refrigerant charge gets weighed in. Now the question remains which im just verifying the answer i was given, does it have to be charged in with liquid or vapor?
-
30-12-2010, 10:59 PM #2
Re: Charging by weight
Ah the old refrigeration conundrum - What weighs more, 1lb of vapour or 1lb of liquid?
What answer were you given and what's your thinking behind it mate?Health and safety first..........unless I'm in a hurry.
-
30-12-2010, 10:59 PM #3
Re: Charging by weight
It depends on the refrigerant, if its a blend then yes it needs to leave the bottle as a liquid.
It depends on a lot of things such as system size, ambient temperatures, type of refrigerant, if you need to get the whole charge in before running the system, as to which method is best at the time.
What type of system are you working on?
-
30-12-2010, 11:10 PM #4
Re: Charging by weight
the systems vary, but mostly R22, R134a and R404a, sometimes R410a. I normally would charge 134a 404a and 410a as liquid, the reason i ask. I recently worked on a scotsman ice machine that spec was 1.5kg of R22. Now i replaced the compressor tecumseh FH5522e originally had AH5522E. but when i charged 1.5kg in it was way overcharged.
-
30-12-2010, 11:27 PM #5
Re: Charging by weight
R134a and R22 can be charged as either a vapour or liquid as they are single component refrigerants.
R404A ,and R410A less so, need to leave the bottle as a liquid to ensure the propper blend is maintained.
-
30-12-2010, 11:40 PM #6
Re: Charging by weight
thought as much, but in the case of the R22 ice maker. 1.5kg of vapor or 1.5kg of liquid? I normally just charge until the superheat is right
-
30-12-2010, 11:50 PM #7
Re: Charging by weight
1.5Kg is 1.5kg. If its over charged with 1.5KG of liquid it will be overcharged with 1.5KG of vapour too. Its the same volume once its in the system.
The main thing with liquid charging is that it is easy to slug the compressor, dilute the oil or overcharge the system as the refrigerant is entering the system relatively quickly.
-
31-12-2010, 12:06 AM #8
Re: Charging by weight
My electronic scales know when it's weighing liquid or vapour and that makes it easy to use as well.
Lawrie
-
31-12-2010, 12:10 AM #9
-
31-12-2010, 12:12 AM #10
-
31-12-2010, 12:15 AM #11
Re: Charging by weight
I may get shot down in flames here, but as a general rule charge any refrigerant that begins with a no.4 only in it's liquid phase...
-
31-12-2010, 12:15 AM #12
-
31-12-2010, 12:18 AM #13
Re: Charging by weight
everyone hold up their hands that don't charge with liquid .... be truthfull now
Reality is an elusion created by alcohol deficiency. Quaff and enjoy. [Yorkshire, UK]
-
31-12-2010, 12:53 AM #14
Re: Charging by weight
nevgee,
when i place an empty cylinder on my scales it reads that weight,,,,when i place a full cylinder on my scales it reads that weight too.
-
31-12-2010, 01:48 AM #15
-
31-12-2010, 09:05 AM #16
Re: Charging by weight
R400 gases are zeotropes and as Monkey says they need to be charged as a liquid (unless I suppose you are going to use the whole bottle up).
R500 are azeotropes which can (along with the other remaining refrigerants) be charged as vapour or liquid.
If not, I'm next to you in the firing line.
Happy New Year!
Andy.Health and safety first..........unless I'm in a hurry.
-
31-12-2010, 12:10 PM #17
Re: Charging by weight
-
31-12-2010, 01:31 PM #18
Re: Charging by weight
Assuming the rest of the system was functioning correctly and the compressor was the correct replacement then I'd have charged by the data plate as well. I've been caught out though taking the plate as gospel I now make sure the charge is correct by measurements afterwards. This particular unit had head pressure through the roof, I recovered roughly twice as much as the data plate, discovered the defrost heater wired permanently on, recharged to the specified weight after rewiring controller. Went back the next day with my tail between my legs to find the system short of charge. Only then did it click that the charge was right all along
Still, got another free lunch out of it!
Cheers,
Andy.Health and safety first..........unless I'm in a hurry.
-
31-12-2010, 04:13 PM #19
Re: Charging by weight
thats what i thought monkey spanners. Bloody so - called senior technicians poking holes in my brains. He claimed that i must only charge with liquid no matter the refrigerant, that if i charge with vapor that not enough liquid will be in the system. LOL
-
31-12-2010, 04:59 PM #20
Re: Charging by weight
hi
you mention that you have replaced the compressor&refrigerant r 404 has different structure and it has different molecule so that is the reason of over charged scotsman ice machine you can charge it by throttle way thats mean thru suction open and close suction must be at 55 psi at the begenning of the refrigeration cycle&32 psi at harvest
Similar Threads
-
Liquid charging through the suction side
By deu58 in forum FundamentalsReplies: 13Last Post: 02-07-2010, 05:23 AM -
Why is suction gauge reading retard during charging?
By acrefconsultant in forum Technical DiscussionsReplies: 10Last Post: 27-09-2009, 08:57 PM -
Frequent refrigerant charging
By desaipt2003 in forum Trouble ShootingReplies: 16Last Post: 31-03-2009, 02:37 AM -
HELP with charging
By damo1206 in forum RefrigerantsReplies: 4Last Post: 27-11-2008, 12:37 AM -
18 seer AS charging problem,best way?
By nagzul in forum Air ConditioningReplies: 3Last Post: 01-05-2008, 07:44 AM