View Full Version : Methol Chloride

29-07-2002, 09:46 AM
Just curious, has anyone ever used Methol Cloride as a refrigerant. The only experience I ever had was breaking a phail on a thermost as an apprentice, only to discover that it contained the nasty gas.
I hear it was used before R12 on apple stores and I noted that BOC had it stocked one day I was looking through their refrigerants.
Regards. Andy:o

29-07-2002, 10:16 PM
An interesting question.

Methyl Chloride is still used in some applications, but not as a refrigerant any more.

I came into the trade in the mid 60?s and the old refrigerants were still in some rare systems but were getting more scarce. Methyl and Ethyl, along with NH3 were in universal use.

As I understand it, the development of Fluorinated gases were in large measure an effort to get rid of these old style refrigerants. They were either toxic or flammable and given the level of maintenance in those pre-war days, leaking seals etc presented a real hazard. People were actually killed by leaks and explosions in the States where the acceptance of home fridges were on the rise.

Methyl has a sweet etherish smell, as I recall. What you remember from thermostat phials, especially if it had a pungent, acrid smell that made you choke, was probably Sulphur Dioxide (SO2 ). If we found an old ?stat with some sulphur in you could sneak in the office and break it off and try to scarper before they caught you. It was guaranteed to clear the place in minutes ? It was probably SO2 that you had.

Hermetic systems were quite common in the 60?s, but 10 years before that a lot of small commercial stuff were small open cabinets and cold rooms etc. and these were converted to the new ?*****s? (usually R 12) whole sale in the 50?s. Most of these old Methyl systems were filthy inside, full of Krud and water and finding a small phial of alcohol or two under the unit was certain give away because alcohol was used to dilute water in the systems to prevent it freezing in the (automatic) expansion valve. Methyl Chloride is also highly flammable. How we never blew ourselves up is beyond me. Bear in mind a lot of motors were split phase start, or in the remnants of district dc supplies on the railways still in use, induction / repulsion. The risk of a spark was all around.

The last SO2 plant I acme across was due to be ripped out and this coincided with the declaration of UDI in Rhodesia in 1964. Ian Smith closed the rail line from Zambia to the Mozambique coast because of trade sanctions and the price of copper on the international market quadrupled overnight and kept rising. This thing was a pre-war Frigidaire unit and had two low side float evaporators with SOLID copper plates 6mm thick. This Was RICHES. Not the paper-thin fins you get now. How we got those coils out without killing ourselves is beyond me.

It also coincided with a miraculous clearance of local rats. Legend has it that they were dying in scores??..

There are probably a lot of engineers? tales waiting for the telling.

Good luck
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Peter Croxall
30-07-2002, 09:49 AM
I am a newcomer to the R.E.forum and I think it is great that engineers from the refrigeration industry, can talk their problems through no matter where in the world they live. It also reinforces the adage "that you are never too old to learn" KEEP UP THE GOOD WORK GUYS !

I also came across Methyle Chloride during the 60's whilst an apprentice.
If I remember correctly there were a couple of cold rooms with open compressor condensing units. The gas had a pleasant sweet smell and it wasn't until many years later did I find out how dangerous this gas was if you were overexposed to it.
From all accounts, if exposed to this gas in large quantities, no imediate effect is apparent. It is only after the water in your body combines with the gas and turns to acid, (I think it was Sulphuric acid) that the damage began, usually after a day or two. NOT A NICE WAY TO GO !!!
We also had an older unit that ran on SO2, if you got a wiff of this gas you would know it for sure. Coughing, weezing and gasping for breath. Decidedly NASTY.

Best regards "The old codger":)

30-07-2002, 07:38 PM
Sounds like it, Peter.

The old timers said that you wrap a wet towel around your face when exposed to SO2. Combined with H2O and some air you should get dilute sulphuric acid, eventually.

That would account for the piles of dead rats, then.......!

They also said that you never get a cold if you worked on ammonia!

We really took some risks in those days. I hate to think of the stippled asbestos that lined coldrooms.

There's no doubt about it, whatever you think of Health & Safety, COSHH, Method statements and all the rest of it, the insidious creeping effect of accumulated exposure to all that nasty stuff has been removed.....

Or has it?
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Peter Croxall
31-07-2002, 08:51 AM
Hi Argus,
I don't think the problems have been removed as newer ones have come on the scene. I was talking to some of the York engineers recently and they were saying that one of the new refrigerants designed to replace R11 in large centrifs, require an oil that is slightly acidic and it was noted by several of the lads, that they were breaking out in rashes whenever they came into contact with this oil. It got to the point where they were refusing to work with it. Of course they were told that it was completely harmless....(Ha ...Ha ..if you believe that you will believe anything) I guess, it must have been in their imagination.


"The old codger"

31-07-2002, 08:14 PM
Hi, Argus, Peter,
Well I learnt something today, many thank's for posting and putting me right on what I tried to gas myself on. The only refrigerant of the lot still in wide-spread use is NH3 a great gas to refrigerant with, an even better on to clear you nose.
Technology has moved on a bit, but we still keep going back to the old stuff, the likes of NH3 and screw compressors, or and pumped circ, I even hear some people are considering Propane again for industrial use.
:( Regards. Andy.

31-07-2002, 08:52 PM

Even I heard that thing abt propane!!
The ban on R 12 greatly intensifies the fascination of being able to use ordinary propane.I heard that propane is compatible with the mineral oil that is used in R-12 systems.
is that true?


31-07-2002, 10:15 PM
I'm convinced, Dan, always been a CFC man, myself!
lots of Carrier 19 series and the like, big absorbers are good fun too, if you have a week to spare.

On my infrequent brushes with NH3, years ago I usually ended up ill for a week so I gave it up as a bad job.

I think that HCs are compatible with mineral oils, though it depends on the purity and the application temperature. Always best to check with the manufacturer first, though.

I agree that NH3 as is Hydrocarbon is important in the right place and has enviable thermodynamic properties. But I think that the problem with all A3 gases is that they have to be confined to specialised systems with secondary refrigerants. Coupled with the added energy costs of pumping the stuff around, insurance and public liability, plant room costs, engineer's costs (I mean someone who knows what they are about), plus scrubbers, leak detection systems..... etc. costs go up and it rapidly looses attraction. After all, nobody wants it in their back yard, do they?

I believe that Star in Glasgow have installed some industrial Hydrocarbon installations, offshore petrrochem, I think. But i don't know any more than that.

I'm all in favour of the right formulation in the right application and that applies to ALL gases.

Our local paper ran a full front page piece last week about a leak of "killer" ammonia gas in a hospital ward at 3 am. The fire brigard turned out and dragged the fridge outside with breathing gear after evacuating the place....
Why do people defrost evaporators with a knife?
No doubt someone got a king size 'counseling' session afterwards

Bring back SO2, I say!

Good luck to all the fridge blokes out there, whatever your prefered poison!
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01-08-2002, 12:10 PM
Yes I beleive Star have some plant running on Propane, but the big thing at the moment is C02 plant, if you have access to this months RAC magazine their is an articile in it about a C02 job, early days, but it looks very promising for the low temp side of a cascade system.:)
As for Propane for a R12 drop in, I stand to be corrected but the pressure would be too high, Propane is a virtual drop in for R22. R12 can be replaced by a mix of Iso-butane and propane. If you go to the post on what refrigerant is best for low temperatures their is a number of very good posts there. Oils used in Propane are usually mineral based, but of a higher viscosity due to it's high misability with mineral oils.
:) Regards. Andy.

Peter Croxall
02-08-2002, 10:42 AM
Hi Guys,
NH3 is a great refrigerant and I believe that it only lost favour because of it's abverse properties, (flamability and health problems). It was used extensively on large plant in the 20's and 30's, i.e. ice making plant, swimming pools etc, but with the technology we have in this day and age, it should not be too much trouble to have leak detection sensors fitted in machine rooms to safeguard personell. Mind you, saying that, when I worked for British Aerospace, (Vickers Armstrong in those days), we had a stratosphere chamber that was cooled by an ammonia plant and you could smell the gas from a long way away. It seems that the old open compressor shaft seals always seemed to leak. A Canadian friend of mine was telling me that there were quite a lot of residential absorbsion units in use now-a-days in the States.
As for HC's, Calor are still trying to push their products and I suppose if good refrigeration practice was followed, it would be one way to go in certain applications. After all they have been using HC's in domestic fridges for the last 20 years in eastern Europe.
Calor also say, on their web site, that Care 30 can be used in automotive applications.....anybody know an car airconditioning unit running on HC's ???? if so it might be interesting to hear from our cousins from across the pool with their opinions on the subject, (as my old Jag's A/C is in dire straights, very low on R12 and I am not convinced that R134a is the way to go in relacing it)

Regards "the old codger"

02-08-2002, 01:55 PM
Hi, Peter,
Nice to hear from you again, old coddger or not.:)

Most of the plants I work with day in and day out are NH3. Nowadays these plants are sited in purpose built plant rooms with leak detections and ventilation, refrigerant charges have decrease significantly even in my short working life time of 12 years. I have under my care a number of low charge systems (Star LPR) coldstore and blast freezer plants up to a capacity of 170 KW none of these plants have a charge of more than 250Kg.
Life is much safer now with eyewash stations and emergency showers fitted outside most NH3 plant rooms, also gone are the days when a leak meant having to add a good 10 bottles to top up your 3000 Kg charge.
I will post a photo of one of my plants, when I get the picture down to size.
:D Regards. Andy. (young pup)

Peter Croxall
03-08-2002, 09:44 AM
That would be great Andy, I look forward to the photo's.