how to remove air from R22 refrigeration system

[Lc_shi]

Who know the practical way of removing air from R22 system? Now I recycle the refrigrant and recharge it. I think it's not effecient. :(

thanks

LC

[clearchris]

Can't you recover to a tank, check the r22 temperature pressure chart for non-condensables, let the tank sit for a few days and you can bleed the air off the top.

It's not a quick answer though, and not really practical in the field.

[Peter_1]

Lc, if air has entered the system, then the LP safety cut-out was not set correct.
Of how many weight of refrigerant we're speaking?
The methods for incondensable removal varies with the weight.
Method used in NH3 system: cool down the liquid to -33°C and open a valve on the cooled receiver. All what escapes is air.
For R22, cool it down to -41°C.

How we remove it?
Empty recovery bottle = 20 kg
We recover all the refrigerant, let's say 60 kg total (20 kg bottle + 40 kg R22)
Vacuum the system
Refill in only-liquid state 39 kg and the remaining is all the air and 1 kg of R22.

@clearchris: your method isn't allowed - theoretically - in the EU.

[clearchris]

Regarding the first method, that won't bleed off *all* the non-condensables, will it? There is still a volume of air space in the tank, at least 20% over here.

[mofrobaggins]

the best way to remove air is to reclaim all the gas in the system and take to an authorized handler to dispose of it (because u suspect it for contamination) for you and then to start again put on vac pull it down to 200 microns and recharge with r 22 but whoever what is the system used for and and running pressures etc for all u know u may even have an inefficient compressor

[Peter_1]

Mofrobaggins, expensive for your customer if you remove all the refrigerant. We use the method sometimes in supermarkets. Air can't contaminate a refrigerant, it only can remain as an incondensable on the top of it.

[Grizzly]

Lc, if air has entered the system, then the LP safety cut-out was not set correct.
Of how many weight of refrigerant we're speaking?
The methods for incondensable removal varies with the weight.
Method used in NH3 system: cool down the liquid to -33°C and open a valve on the cooled receiver. All what escapes is air.
For R22, cool it down to -41°C.

How we remove it?
Empty recovery bottle = 20 kg
We recover all the refrigerant, let's say 60 kg total (20 kg bottle + 40 kg R22)
Vacuum the system
Refill in only-liquid state 39 kg and the remaining is all the air and 1 kg of R22.

@clearchris: your method isn't allowed - theoretically - in the EU.

Useful tip their Peter.
Grizzly

[Aik]

In such cases we unify two bottles: one empty, one with refrigerant and air. Bottle with refrigerant and air remove on warm place, empty bottle leave on cold room (-18 C for example). After 24 hours refrigerant migrate from warm bottle to cold empty bottle, air and refrigerant in gas phase would be in warm bottle.

[billy7]

in my understanding without all the bumf and cost is reclame of top of condenser or discharge if no nrv, air usally sits on top of condenser and this can be found with cool condenser at top and hot twords bottom

[gman082]

Who know the practical way of removing air from R22 system? Now I recycle the refrigrant and recharge it. I think it's not effecient. :(

thanks
LC

Hi LC,
you're right, it's un-economical to keep reclaiming and recharging refrigerant, for you and your client.
As I understand, if there's air getting into your clients sealed refrigeration system, I'd say start looking for a leak.

@clearchris: Neither can I recomend this practise, our job should be to minimalise refrigerant expelled to the ozone.


... Air can't contaminate a refrigerant, it only can remain as an incondensable on the top of it.
@Peter_1: True, air is made up of lots different parts, that may remain uncondensible and un-noticed, but the moisture carried in the air can affect the hydroscopic oils and cause problems.

Hope this helps!

-Gr.

[Fri3Oil System]

@Peter_1: True, air is made up of lots different parts, that may remain uncondensible and un-noticed, but the moisture carried in the air can affect the hydroscopic oils and cause problems.

Hope this helps!

-Gr.
Normally R22 uses MO which is less hygroscopic than POE. Anyway, once you have removed the uncondensables, as Peter_1 smartly suggested, you can then recycle the gas, and remove oils and moisture.

Regards,

Nando.

[NoNickName]

Lc, if air has entered the system, then the LP safety cut-out was not set correct.


And this reminds me about the deprecated habit of german supermarkets (BILLA, REWE) especially with TEKO equipment to use R134a in freezer cabinets. Only because R134a has a lower TEWI than R404a.

[gman082]

I almost forgot, (credit where credit's due, they say)... I agree with Mofobaggins (post #5), contamination is the word on the street kids. I'd suggest a dry nitro pressure test too, just to be sure I got the leak.


Mofrobaggins, expensive for your customer if you remove all the refrigerant.
It maybe an expensive exercise, but I find clients warm to the idea of having a fresh, clean charge of refrigerant with a guarantee.



Normally R22 uses MO which is less hygroscopic than POE. Anyway, once you have removed the uncondensables, as Peter_1 smartly suggested, you can then recycle the gas, and remove oils and moisture.

Regards,

Nando.

Hi Nando,
now I not arguing with you, I'm whole-heartedly agreeing instead; You say less hydroscopic, very true, but is still hydroscopic all the same. Furthermore, your acid test kit will only tell you acid is present in the oil, not the quantity.

[Peter_1]

Gman082, if you recover the liquid without the 'gas-mixture' above the liquid through a burnout filter - in case you suspect acid in it - then you will have pure R22. Sometimes more pure then the R22 in new bottles because they don't clean each bottle when it's coming back in the refilling stations.
We've done it so many times with 100% good results that nobody can convince me from the opposite.
Then, what's better for the environment, me reclaiming it or your giving it back to destroy?

[gman082]

Gman082, if you recover the liquid without the 'gas-mixture' above the liquid through a burnout filter - in case you suspect acid in it - then you will have pure R22. Sometimes more pure then the R22 in new bottles because they don't clean each bottle when it's coming back in the refilling stations.
We've done it so many times with 100% good results that nobody can convince me from the opposite.
Then, what's better for the environment, me reclaiming it or your giving it back to destroy?


Peter,
I understand your reasoning, thanks.
I have one last question if you'd be kind; When your recovering liquid from a unit that has a suspected leak and an unknown refrigerant charge, how do you know how much refrigerant to take out, so you avoid recovering any vapour?

-Gr.

[Peter_1]

How we remove it?
Empty recovery bottle = 20 kg
We recover all the refrigerant, let's say 60 kg total (20 kg bottle + 40 kg R22)
Vacuum the system
Refill in only-liquid state 39 kg and the remaining is all the air and 1 kg of R22.

I have to add to my 3th post, we recover everything, liquid, gas and also the non-condensables.
We then recover only +/-95% from the recovered 'mixture' - in liquid phase - and let the remaining liquid with the gas and the non-condensables still on top of this mixture in the recovery bottle.

[NoNickName]

Just a thought: if one recovers refrigerant and installs a liquid receiver, through-type, in between the condensing unit and the bottle, incondensables should float in the receiver? Is there a risk of exceeding the safety pressure?

[Peter_1]

When you start, when there's no liquid yet in the, non-condensables will flow through it.
If you have vacuumed a cylinder where the recovered R22 will flow to, then even with a liquid seal in the receiver, the liquid will flow so fast to the bottle that it will empty.
High pressure NNN: in many occasions, we see that our recovery station, cutting out at 26 bar actually cuts out on it's safety pressure. We end up many times with cylinders R40c or R404a at 25 bar when we come back the next morning.
We therefore installed a safety HP between the mains of our recovery station, cutting out at 23 bar.
And...also a LP cut out just above atmospheric pressure.
Most recovery go to 500 mbar absolute or lower (=vacuum)
EN378 states that you have to recover till 300 mbar absolute before opening the system. Typically, a rule invented by peoples not working in the field with their hands but only behind their desks.
Why? If you have a leak in the system - often the reason for a recovery - your recovery unit will continue to recover through the leak, sucking in air resulting in an increase of pressure of the recovery cylinder.
Therefore, the 300 mbara rule is for me not a good rule.

[Peter_1]

But we use a vertical receiver if we need to charge a lot of oil in a compressor/system.
Filling up the receiver via a funnel via the rotalock, 4 l at once. Screwing back the rotalock, vacuum out the air via the intake service connection. Pressurize then the receiver with HP refrigerant when system is already running or with the gas from a cylinder if system is at vacuum and pushing out the oil via the receiver outlet. We fill in this way 20 l in +/- 20 minutes.

[icecube51]

I am used to work whit two filter/dryers on my recovery station. one when i am recovering and a other one when i am refilling the unit. That way i am always sure to have clean refrig in mi installations.
The cost of the filters is negligible to the cost of say 25 kg of refrig.

One rule of thumb do, never take so much refrig out of the bottle so the station go's in vacuum.
Ice

[Fri3Oil System]

Hi Nando,
now I not arguing with you, I'm whole-heartedly agreeing instead; You say less hydroscopic, very true, but is still hydroscopic all the same. Furthermore, your acid test kit will only tell you acid is present in the oil, not the quantity.

My acid test? Which acid test? :)

[shooter]

**** all illegal answers!!
the only way in a running installation is to use a purger on the receiver or condenser.
It cools the gas very low so all R22 will condense and flow back.
the air will be purged by a very small hole.
look for grasso purger.
you can use it on many systems as the only connection is one pipe.
and when it runs for a month all air will be out.

all other methods are illegal.