PDA

View Full Version : Newbie question on gas recovery







bigcw
21-02-2017, 11:32 PM
Hi everyone

First post, and newbie refrigeration engineer here. I qualified just before Christmas so I am just finding my feet hence why this is probably a very simple question.

I have been tasked with decommissioning an old Denco R22 water chiller but am struggling to work out how to connect my gauges, and therefore my recovery machine, to it. It doesn't seem to have any service valves anywhere, just these schrader-type connections on the high and low pressure sides of the compressors. I seem to remember from my course that we used one of these for the vacuum gauge when pumping down the system.

So my question: can I use these valves for refrigerant recovery?

If I can, do I need some kind of adapter to push down the valve or will my standard hoses work? I've got a Javac gauge set and the standard hoses that came with it if that makes any difference.

If not, what should I be looking for instead to connect to?

I've attached a photo. Note that it has been sat outside for a while hence the rust!

Would appreciate any pointers.

Thanks, Chris

The Viking
21-02-2017, 11:51 PM
Hi Bigcv and welcome to the forum.

The standard hoses for your manifold will have shrader depressors in one of the ends. Technically you can use these to connect to the system BUT this takes a lot of practice before you can do it safely without risking burning yourself on liquid refrigerant and loosing gas.
The safer option is to use Quick Couplers on the end of your hoses and if you are looking at recovering a lot of refrigerant then the fastest would be to connect your hoses to the system using core removal tools.

:cool:

Grizzly
22-02-2017, 07:12 AM
Hello bigcw.
Yours is what used to be a common dilemma, where old R22 systems were built with little or no access points.
Because back in the dark ages 22 was just blown off. (Released to atmosphere.
Since then system designs have evolved to comply with the new legislations!

Looking at the state of the system I wonder if any refrigerant is still in the system?

Quick couplers are indeed the way to go.
Given your lack of suitable valve locations you could use a line tap attachment,
Just google "Refrigeration Line Tap" and you will see what I mean.
A 1/4" tap on the Liquid line (Say by the filter drier- Condenser side would be good)
They are listed as around 5.00 and are reusable. So they are a useful addition to the toolbox.
Grizzly

Rob White
22-02-2017, 08:22 AM
.

Schrader type connectors are extremely slow for refrigerant
recovery due to the restriction of the valve. The kwick couplers
are good for measuring pressures and such but again slow the
refrigerant transfer down.
There are schrader valve removal tools available and they allow
you to pull the valve out of the scrader fitting and then you can
move refrigerant as quick as possible.

The hoses you have will have schrader depressors on the 45 degree
angle end and they will work.

Rob

.

frank
22-02-2017, 07:33 PM
Hello bigcw

What did you qualify as before Christmas?

bigcw
23-02-2017, 01:27 PM
Thanks for the advice everyone.

Those line tap things look like a good way to go. I assume they have a valve on them so the gas doesn't escape in the time between putting them on the line and fitting the hose?

Intrigued by this tool that can remove the schrader valves. Surely this can only be done once the system is empty as the gas would pour out if the valve was removed?

frank: by 'qualified' I mean passed the f-gas course (class 1 C&G if that makes any difference). I'm only working on my own equipment at the moment; I own a business in the telecoms sector that uses a lot of air conditioning equipment.

Cheers, Chris

Brian_UK
23-02-2017, 02:30 PM
Mutters quietly, "Boy he's got a lot to learn", and sits back in the corner again. :p

bigcw
23-02-2017, 03:35 PM
Mutters quietly, "Boy he's got a lot to learn", and sits back in the corner again. :p

Don't I know it! :)

Rob White
24-02-2017, 01:16 PM
Thanks for the advice everyone.



Intrigued by this tool that can remove the schrader valves. Surely this can only be done once the system is empty as the gas would pour out if the valve was removed?



Cheers, Chris

No it is a valve arrangement that allows the valve core to
be removed while the system is still pressurised with
refrigerant.

By attaching and opening the valve in a select way the core
can be removed while refrigerant is present.

Rob

.

bigcw
27-02-2017, 11:51 AM
Thanks for explaining, Rob.

Sorry to sound dumb (as above, I'm a complete newbie!) but is this the right thing?

https://www.airconspares.com/product/1359/Javac-EL41550-Standard-Valve-Core-Remover-Installer

*Admin note: I have no affiliation to that company, it just came up when I searched

Are they all the same? As in there are no 'different' valves that this won't get out?

Do I need to get one for each side? When we did recovery on the course we pulled from both the high side (with the valve just cracked open slightly to only get gas out) and the low side? Presumably I can just pull from one side and just suffer the extra time it will take?

By the way, thanks again for the advice everyone.

Chris

Brian_UK
27-02-2017, 01:19 PM
Yes thats the beastie, make sure that the one you get has both adapter sizes, R410a and regular. Having more than one is always good.

bigcw
27-02-2017, 01:37 PM
Thanks Brian. Have ordered one, hopefully it will be ok just pulling gas from one side. If it takes a while I don't actually mind too much as I'll be on site doing other jobs anyway so can just leave it running.

Don't have any R410a stuff yet but keeping an eye on eBay for a decent set of gauges at a good price. All I have done so far is R407 or R134a (the latter to gas down a car system before I took it to bits)

Chris

Contactor
03-03-2017, 10:40 PM
You could close service valve, remove the shrader core if you must, attach line without quick coupler and then open the valve again. Apply voltage to expansion valve or use magnet to open it so that you can recover both sides of the system through your service valve. Quick couplers are a gimmick, use the valve

Contactor
03-03-2017, 11:15 PM
That thing is a service valve, remove plastic valve seal cap to gain access to valve stem. You often find service valves stuck on the side of compressors, you might get some oil but you can recover from anywhere. If its a chiller you might find another shrader by the expansion device, often used to check depth of vacuum, but you could recover from there as well

bigcw
06-03-2017, 10:02 AM
Thanks for all the advice. Did the job on Saturday. The schrader tool worked a treat and I recovered about 7kg of R22 out of it.

Interesting point: the data plate on the unit said 1 circuit with 1.4kg of R22 but it was not the case. The system very clearly had two large hermetically sealed compressors, two separate circuits, and I got about 3.5kg out of each one. Is it common for data plates to be 'wrong'?

One idea I had: could it be that the unit was retrofitted with a different gas at some time in it's life? Do keep in mind though that the building has been mothballed since 1990. I've no idea if R22 was still current back then and/or whether that is before people knew/cared about how bad it was for the environment?

Chris