Dismantling fridge/freezer

You just turn your head and cut one of the pipes (outdoors). Walk away until it's finished hissing, and you're done. I've done this at least half a dozen times in the past.

Make sure the compressor is upright when you do this, and that it has been upright for a couple of hours (with the main heat exchanger above it). Otherwise you're likely to lose all the oil along with the refrigerant.

Some fridges used ammonia as the refrigerant. When I was at school, I once removed the compressor from a fridge containing ammonia. That was an unpleasant experience. Just make sure you do it outside, away from other people/animals etc.

I thought ammonia based frigs didn't have compressors?

IIRC an old book of how things work that my father has, ammonia was used as a refrigerant in early compressor fridges as well as in those which operate(d) with a heat source. I am sure that I can also remember there being gas fridges in the past which presumably used a heat source in some way, but I can't think for a moment what the principle of operation would be.

.andy

To email, substitute .nospam with .gl

Ah, thank you. I didn't know that.

They use the heat of solution of ammonia in water. A heater drives the ammonia out of solution from the water, a radiator cools it, convection causes the water to circulate back into the frig, wherre the ammonia is redissolved and the heat of solution absorbed from the frig interior. Entirely silent and no moving parts.

My parents had one for 30-odd years until they emigrated to the USA and left it behind.

Yes, the water/ammonia mechanism you describe was used in heat-driven fridges, but neat ammonia was also used as a refrigerant in some old compressor driven ones.

Ta.

You learn something old every day!

I am sure that I can also

Not only in the past - very much in the present for caravanners!

Caravan fridges invariably work on the absorption ("Electrolux") cycle principle - rather than having compressors - and usually have 3 alternative sources of heat:

1. Mains electricity
2. 12v DC (for use when travelling only - and powered by the towcar's alternator)
3. Calor Gas (for use on site when no mains electricity is available)

Roger

Ammonia is still used in very large industrial fridges, like coldstore warehouses.

The compressors are very useful - but make sure you fit a pressure relief valve, although their capacity is low they will happily go up to inordinately high pressures (many hundreds of PSI) before something gives.

Just what can they be used for? I cant think of much offhand. I heard they make usable vacuum pumps, but must never be tipped up once de-fridged.

Regards, NT

Having learned how liquid nitrogen is made in O-level physics, I recall trying to get hold of one to make some. It would probably have never worked, but I never got to try.

I've got a freezer which is on it's last legs (has to wear a large incontinence nappy due to failed insulation). The compressor seems fine however, so I could perhaps try it with that one when I finally chuck it out.

I don't know how long it would last when asked to provide much more pressure than it was wont, without any lubrication in the working fluid which is now nirogen, and with much less flow through it to carry away waste heat.

However I'm looking forward to reding about what happens.

I used to mess around with compressors a lot, and they don't do too badly as long as you keep them upright and keep the oil in. I had one that was still pulling good vacuum after 2 years of vacuum use.

How did you get the dust out?

Vacuum pumps, as you mentioned, excellent airbrush compressors (look at the ones sold for GBP100 plus and see how they are made). Good compressors where the need is pressure rather than volume - I know of a complex watering/misting system for orchids controlled entirely by pneumatic pressure from an old fridge compressor.

Presumably that's missing a smilie, right?

Here it is ;o)