Charging liquid through suction line?

I was taught to add feon in a system that lost some charge do to a leak, after repairing leak of course. To charge system with liquid through suction line at 10 lbs. over low side pressure. I never had a problem. I was told this is a very bad way to charge a system. Unless there is a accumulator installed and you charge through the accumulator. have i been damaging the compressors by charging liquid through suction line? I thank everyone of the mechanics who has been helping in the past. This site has baled me out many times!!!

possibly yes sir :D
as a we all know airconditioner compressors cannot compress liquid refrigerants. if your accumulator will be flooded by the excess liquid refrigerant then chances are you will be damaging your compressor

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Originally Posted by SloFuse

I was taught to add feon in a system that lost some charge do to a leak, after repairing leak of course. To charge system with liquid through suction line at 10 lbs. over low side pressure. I never had a problem. I was told this is a very bad way to charge a system. Unless there is a accumulator installed and you charge through the accumulator. have i been damaging the compressors by charging liquid through suction line? I thank everyone of the mechanics who has been helping in the past. This site has baled me out many times!!!

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Hi SloFuse.
Have a read of this post.......
http://www.refrigeration-engineer.co...ad.php?t=13526

I hope it will clarify things a little?
Grizzly

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Originally Posted by SloFuse

To charge system with liquid through suction line at 10 lbs. over low side pressure.

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I dislike statements like this because they imply if you keep the pressure at or under 10 psi this process is acceptable. I think it is more prudent to charge the liquid at a low enough pressure to ensure the oil does not foam or the discharge temperature does not drop. If either of these occur then you are charging too much liquid, regardless of pressure over suction.;)

I was always taught that this is acceptable as long as you "pulse" the refrigerant in to avoid stripping oil and injecting liquid directly into the compressor.

The issue here is the controlled introduction of refrigerant into the system. Slow and steady is the way to do it.

I concur with previous mentioned steps, go easy charging liquid, don't rush it... I've been to the copeland coss classes more than once and the experts say the same thing, don't rush it.. Meter the blends in slowly, take the time to explain the process to your customer so they have an idea why it takes all the time that it will take, and charge (your billing) accordingly... If charged too fast the liquid will take the place of the oil and damage metal surfaces inside the compressor... Gentleman, or ladies, take your own sweet southern time, patience is a virtue..
cheers, kooler

I will describe how I do it when I charging thru low side.
If I know total amount, I charge by weight reading the amount drawn on scale and throttling on manifold valve.
I usually keep rate of charging by 2-5% (higher at beginning and lower at the end of charging process) of total charge in one minute, while watching that sight glass on my Refco 4 valve manifolds is not full of liquid (I keep sight glass with lots of bubbles). After 1/2 to 1 minute, I stop feeding refrigerant and wait for another minute or two that accumulated refrigerant (if any) evaporates. Then I start feed refrigerant again.
If I don't know total amount, I charge slowly, keeping sight glass on manifolds without liquid and interrupting frequently to check pressures. When they are near to be good, I look in scale and proceed with charging about 1-2% of total amount charged so far.
Now, I measuring subcooling, after some time system stabilize, and judging if it is more needed.
That is my way, which I adopted from my experience and after reading a lot of articles about proper charging methods. It works relatively fast and it is accurate and don't make any damage to system.

I think you sould do it the way nike123 described it and also check oil foaming if you have oil sight glass in site.

Yo Nike,

i think you had lessons from an oldtimer in the business ;) , its true that we play on sure.

keep up the good work,

Ice

Quote:

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Originally Posted by SloFuse

I was taught to add feon in a system that lost some charge do to a leak, after repairing leak of course. To charge system with liquid through suction line at 10 lbs. over low side pressure. I never had a problem. I was told this is a very bad way to charge a system. Unless there is a accumulator installed and you charge through the accumulator. have i been damaging the compressors by charging liquid through suction line? I thank everyone of the mechanics who has been helping in the past. This site has baled me out many times!!!

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blended refrigerants like R404a should only ever be liquad charged.
ive been to many jobs where its been flooding back due to evap fan failing etc and the compressor is a block of ice and it still runs and has a full and prosperous life , think of how much liquad a 7/8" liquad line and 2 big tx valves can throw at a 20 hp compressor during flood back compared to your 1/4" gauge line,conversly i wouldnt go dumping liquad flat out into a small display icecream freezer etc

You have to charge by liquid with the newer blends. Meter it slowly. I have an "Bulls Eye" sight glass on my suction hose at the manifold so I can see how much is going through. Been doing it this way for eeons. Just don't open it up so wide or you will hurt the compressor.

Guys
I have always taught the apprentices under my supervision to look at the suction pressure and feed the liquid in at 0.2 bar above that as the suction pressure rises due to the extra refrigerant the flow of liquid stops thus reducing the chance of overcharging. When the flow stops check the suction pressure and repeat the process.
Personally over the last 30 plus years I have charged liquid into the suction of many compressors and to this date have never damaged one by hydraulic lock due to liquid, however I do accept that unless you are vigilant it is possible to wash the oil out. As previously stated slow and easy is always the best route to take and at the end of the day as engineers we are getting paid to be there so think of the overtime.

Ian

As always the oldsters know best lol
New blend refrigerants should ALWAYS be added as a liquid otherwise the final blend will be wrong.
However you should NEVER put too much liquid into the suction line especially on a recip as you could damage the reeds
It would be advisable to fit a length of capilliary, a carrier accurator or a kwic-charger (available through HRP, other distributors are available) to your charging hose so the refrigerant enters the suction line as a gas.

Brit

can i add 410a refrigerant to the suction side, while the unit is running. i understand i have to crack open the service valve a little

Tigers 90, you're asking twice the same question in a thread of 2 years old and in one you even respond to your own question...: