Liquid charging through the suction side

I work on ships as ships crew, In my job I'm pretty much all by myself, Generally I will be the only person on board that knows anything abut the reefer systems, I am mostly self taught by manuals and experience, Every manual or publication I have ever read concerning charging a system specifically states do not charge as a liquid through the suction line, Obvious, Liquids do not compress,

So if a system is a little short I dutifully charge as a vapor through the suction line always with out exception, Works great for smaller systems, But on large systems even with a heat blanket on the bottle it takes forever and a day,

When in Port we do have a service contractor that occasionally comes to the ship to look things over, I asked their guys about a faster way to charge and they all say just charge liquid through the suction line, I thought HUH??? so when off the ship and hanging around the hiring hall I asked some other older more experienced reefer's the same question and I get the same answer,

I have been told that if you just crack open the liquid valve at the bottle it atomizes the liquid and all will be well, I have not tried to check this theory yet, Reason being that almost every new ship I go to the compressors have just been rebuilt due to broken rings and valves,

I do know that Robinair has a fitting that can be used to charge liquid through the suction side, But I am worried to even use that, If I were to screw up the ships AC in the Indian Ocean I would be very unpopular,

I am asking about just topping up a charge that is short, I know that on large installations if a full charge needs to added/replaced that they will use a small pump through the King valve, Or breaking vacuum charging liquid through the king valve on a smaller system and then start the system and finish charging as vapor,

Any tips advice corrections etc would be appreciated,

deu58

Deu58
You are right to be cautious when charging with liquid but it is a very common way to quickly get a bit of gas in. The charging device you mention is used to ensure a full blend of the refrigerant is charged and not the individual element of a blend. This is the easiest way in which to safely charge a blended refrigerant. If you do want to charge with liquid into the suction try and stay as far away from the compressor as possible (this will give the liquid time to boil off) and constantly watch for icing, (not so easy on larger kit). Listen for any pitch or noise change in the compressor and monitor the run amps as you charge. I'm sure you will get some other interesting advice.

cheers

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I do know that Robinair has a fitting that can be used to charge liquid through the suction side, But I am worried to even use that, If I were to screw up the ships AC in the Indian Ocean I would be very unpopular

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You can also charge liquid slowly before the liquid separator.

The Robinair "thing" is OK, Imperial makes olso such a "thing".

If I were you, I would worry more from the sharks in the Indian Ocean.........;)


Chemi :)

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Originally Posted by deu58

Any tips advice corrections etc would be appreciated,

deu58

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First what refrigerant is it?
Is it R22?

I you charge a zeotropic refrigerant as a vapour then you will cause seperation of the individual gases that make up the refrigerant.

All refrigerants should be treated as a zeotropic which means chargeing shold be done as a liquid only.

Now as you well know you must never let liquid enter the comp so there is the problem!!!
We need to charge the lquid into the system as the system is running and the way it is done is by chargeing as a liquid into the suction line.
There are a few ways to do this without causeing harm.

1 Throtle the liquid into the suction by restricting the flow of liquid by controling the gauge valve. Let the liquid enter at about 1/2 a bar (5 or 6 psi) above the suction running pressure.

2 Throtle the liquid by useing a vaporizor. A device that vaporizes the liquid.

If you are working with R22 then you can charge with liquid but you must be very, very, very careful.

Cheers taz.

Hi guys

Thank you for your answers, So I guess the verdict is in, Yes you can as long as caution is observed, Most of the ships are old so they are still using r-22, Some of our control air driers and galley equipment are still r-12 even,

Not sure how all the new rules affect the maritime industry, Most of the ships I ride are on the Asian run and we try to buy all our gas over there, But any vessels that are coastal or inland surely will have to comply ASAP, In our industry what is sauce for the goose is not always sauce for the gander,

As to Indian Ocean sharks, If I screw up the AC that could be a real problem!!!:D

deu58

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Originally Posted by deu58

Hi guys

Not sure how all the new rules affect the maritime industry, Most of the ships I ride are on the Asian run and we try to buy all our gas over there,
deu58

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I'm not sure about that because a ship is mobile and anything that is classed as mobile does not as yet conform to the same regulations as static refrigeration. So that may give the ship owners a getout clause regarding cfc phaseout.

Cheers taz.

Apart from the risk of damage to the reeds etc it's as well to be aware of the damage that can occur as a result of oil dilution. As others have said - be very very careful.

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Originally Posted by taz24

I'm not sure about that because a ship is mobile and anything that is classed as mobile does not as yet conform to the same regulations as static refrigeration. So that may give the ship owners a getout clause regarding cfc phaseout.

Cheers taz.

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Right, There are all kinds of things that go on that are all above my pay grade, Companies get waivers and all kinds of stuff,

Eventually they will all have to comply though,

Matson for instance had three new ships built fairly recently, I was on one awhile back and the AC's on there were 407-c I think it was,

But now all I have to do is convince the chiefs that it is ok to charge as a liquid through the suction side:o

I will be getting a chance to do that soon, I am flying out thursday morning to meet a ship that goes through the Suez and operates in the Red Sea,

Sea temps are so high there in the hot season that when you land a fish it is already cooked!:D

Again thanks to one and all for all the input, This is really a great site for learnining and asking questions, and glad I found it, Lots of things that I wondered about and found answers just by browsing the old threads here, To bad I have to leave so soon

deu58

Why not make a charge-valve in the liquidline from the liquidvessel?
It makes charging much easier.
Rob

can i charge liquid thur the suction line on a new unit. if i crack the guages valve slight open. i know i have to charge by the sub cool method on a lot of 410a new systems.

i know i can add 410a on the suction side in liquid if i just crack the manifold guages valve slightly open.

You could charge liquid by front seating the King valve

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Originally Posted by tigers90

can i charge liquid thur the suction line on a new unit. if i crack the guages valve slight open. i know i have to charge by the sub cool method on a lot of 410a new systems.

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Yes you can charge as a liquid.

YOU MUST charge as a liquid

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Originally Posted by tigers90

i know i can add 410a on the suction side in liquid if i just crack the manifold guages valve slightly open.

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Yes just bleed it into the suction. The further away from the comp the better. If you are working with 410 then I assume you are working on air conditioners?
Most good air conds have suction accumilators before the comp to stop liquid entering the comp..

coolrunnings

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You could also put a shut off valve in liquid line, mostly ball valves used here and add 3/8 access port to evap coil side of valve, slow liquid flow down by closing ball valve watch your guages make sure you don't pump her down to far when doing this... Now connect your bottle with 3/8 nipple and line to system and purge line to system... Now open up your liquid on bottle to system and close liquid port line. System will suck in liquid straight from bottle. Get about 60kg's gas in, in about 5 mins or there abouts.

If 3/8 to big put 1/4 line in or 1/2 inch if system takes hundreds of kg's. Of course it's a quick way to add gas to system when you need at add large amounts of gas you can as a liquid. But would have to add valves etc when system offline being repaired if not already there.


I've only worked on a few reefers here, most 20ft chillers running on 134a I think had about 10kg or there abouts. You could vac system and dump 7~8kg liquid in liquid/discharge side of system if fixing system after vac...

You could also throttle the liquid into suction side slowerly, by this I mean open manifold for a second close say 3 to 4 seconds. Listen to compresser etc make sure no weird sounds happening... Watch your guages too if you start to see lines and pipe connecting into system freezing up slow up a little as there's a bit of liquid there..

Anyway hope I helped, or confused the absolute hell out of you lol...

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Originally Posted by Bones

You could also put a shut off valve in liquid line, mostly ball valves used here and add 3/8 access port to evap coil side of valve, slow liquid flow down by closing ball valve watch your guages make sure you don't pump her down to far when doing this... Now connect your bottle with 3/8 nipple and line to system and purge line to system... Now open up your liquid on bottle to system and close liquid port line. System will suck in liquid straight from bottle. Get about 60kg's gas in, in about 5 mins or there abouts.

If 3/8 to big put 1/4 line in or 1/2 inch if system takes hundreds of kg's. Of course it's a quick way to add gas to system when you need at add large amounts of gas you can as a liquid. But would have to add valves etc when system offline being repaired if not already there.


I've only worked on a few reefers here, most 20ft chillers running on 134a I think had about 10kg or there abouts. You could vac system and dump 7~8kg liquid in liquid/discharge side of system if fixing system after vac...

You could also throttle the liquid into suction side slowerly, by this I mean open manifold for a second close say 3 to 4 seconds. Listen to compresser etc make sure no weird sounds happening... Watch your guages too if you start to see lines and pipe connecting into system freezing up slow up a little as there's a bit of liquid there..

Anyway hope I helped, or confused the absolute hell out of you lol...

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