refrigeration system air-tightness test

[Lc_shi]

Hi sirs
We usually use Nitrogen gas to test the referigeration system. Is there any problem if changing to compressed air(of course,by drier filter)?

thx

LC

[Dan]

Moisture. The filter drier will not collect all the moisture in the air. This will complicate or extend your vacuum process, perhaps even resulting in residual moisture resting in the oil and other odd places.

[raviperumal]

Can you able to heat the air further, so that the moisture can be removed.The condition of air may at superheated zone.

Best regards,
ravi perumal

[The Viking]

No problems at all technically.

But it's not a cost effective way of doing it.
The air you need is Breathing quality (Scuba diving), this is as dry as OFN.

The big question is why.....
You will still need OFN for your brazing and the cost of Breathing quality air is probably higher than OFN, add to this the cost of cylinders, regulators and so on......

[Lc_shi]

it's not O2.Just using air compressor and drier filter to produce the needed compressed air.

[Cofreth]

Better to have the compressed air passed through an Air Drier or if possible, a Munter dehumidifier before charging into the refrigerant system.

[Peter_1]

Lc,
Will contact you soon.

Just an idea, why not pass the air over a coil held at -80°C (moisture trap) and then let is pass through a filter dryer.

But Viking has a point, you still need OFN for brazing.

Lci, you also can use a small OFN generator (membrane technology) and a manufacturer in your country makes these incorporated in a tire inflater for cars.

[LRAC]

Sorry to butt in on a air pressure testing system discussion but not sure if i'm being hood winked on the following.

We have been informed by a manufacturer that has equipment running on R410a that they do not recomend pressure testing with OFN, due to the fact that the molecules on R410a are much smaller than nitrogen and may still leak.

They suggest using helium is someone taking the Micky out of me?

Kind regards
Lrac

[Peter_1]

What kind of b.s. is this your manufacturer is telling you?

For me , there's a big difference between pressure testing and leak testing or leak searching.

If a leak is that small that only the size of a molecule of helium or OFN or dry air can escape through that leak, then what sort of leaks are we talking about?

Pressure testing is a holding test. Leak testing is done with an electronic device which can detects the tracer gas inside the system.

At Copeland, they told me that they use helium because it has smaller molecules but the main reason was because there are leak testers available on the market which can detect helium very fast and more reliable then our commercial leak testers.

They place the compressors in a closed doom and they insert some helium in that doom. The same time, the compressor is heated (DC through the motor windings) and vacuumed. On the outlet of the vacuum pump is the leak detection. So the helium is going from outisde to inside the compressor.

If you can pressure test test for 24 hours and the pressure doesn't change, then the sort of gas you've used doesn't matter any longer.
That's my vision.

[Peter_1]

What kind of b.s. is this your manufacturer is telling you?

For me , there's a big difference between pressure testing and leak testing or leak searching.

If a leak is that small that only the size of a molecule of helium or OFN or dry air can escape through that leak, then what sort of leaks are we talking about?

Pressure testing is a holding test. Leak testing is done with an electronic device which can detects the tracer gas inside the system.

At Copeland, they told me that they use helium because it has smaller molecules but the main reason was because there are leak testers available on the market which can detect helium very fast and more reliable then our commercial leak testers.

They place the compressors in a closed doom and they insert some helium in that doom. The same time, the compressor is heated (DC through the motor windings) and vacuumed. On the outlet of the vacuum pump is the leak detection. So the helium is going from outisde to inside the compressor.

If you can pressure test test for 24 hours and the pressure doesn't change, then the sort of gas you've used doesn't matter any longer.
That's my vision.

[US Iceman]

I would agree with Peter.

Helium leak checking is an extreme form. I can't believe Nitrogen would not suffice for any pressure test.

[peterwatson4]

Hi to all, I was looking on the internet for info about tube bursting pressures etc when I found your site.

While searching I found this Advice, it seems to suggest 'Dont use compressed air for pressure testing, as it is not inert'
regardless of moisture content.

[chemi-cool]

I have just repaced a 15 hp Coplematic.

It comes from the factory charged with dry air so I dont see any problems with that.

Chemi

[peterwatson4]

yes chemi,
sure, they do supply compressors with a shipping charge of dry air, but pressure testing a system is a completely different animal, dont you agree?

[adams?]

on the helium thing what lrac has been told is in a sense correct although the molecules are not nessecarily smaller but different shape. crude examlple, if cfcs and hcfcs are football shaped nitrogen is tennis ball shaped therefore nitrogen is effective. however hfcs are sausage shaped and can leak out of a hole that nitrogen cant - this is why they can be a nightmare to find. helium is expensive but you can get a ofn he mix which is what i use on troublesome systems helium being table tennis ball size - always does the trick!

[Pooh]

LRAC
is actually correct due to the size of the R134a molecules, R134a is approximately a tenth of the size of R12 which we used OFN quite satisfactoraly to pressure test with however due to the reduced size of the molecules helium is a better bet for leak testing and several manufacturers recommend its use. I know of lots of companies using helium for this purpose.
On the subject of using compressed air, no matter how well dried it is not the correct gas to use and why go against standard industry standards unless it is to save money, if so you reap what you sow.

Ian

[Peter_1]

....d. helium is expensive but you can get a ofn he mix which is what i use on troublesome systems helium being table tennis ball size - always does the trick!

What sort of leak detector are you uising then to find the leak?

[adams?]

old fashioned bubble spray, never really got on with electronic ones

[Lc_shi]

I know helium detection is applying in PHE production line and also used in many large air conditoner manufacturer in China and then it warrant the system no need adding charge within 8 years.

[adrian m]

Agramkow do these helium pieces of kit they are for commercial high volume fridge companies you connect via speed fittings to the section and discharge line and it can even tell you if the the capillary is blocked or narrowed full pulldown and leak detection in 50 seconds multi banked very expensive indeed

[adrian m]

Peter at Cornelius we use mass spectrometers set to each specific refrigerant not very portable but will pick up down to 0.4 of a gram per year can go lower but we only give a years guarantee on equipment