which compressor

[ALAN STAMMERS 1Participant @alanstammers1]

I am looking to purchase a low noise small compressor to run my 6 live steam model engines [ up to a twin stuart turner Victoria ] but I know nothing about compressors. SO hoping one of you can help me to decide what I need. a second hand one would be fine.thank you Alan

[ALAN STAMMERS 1Participant @alanstammers1]

[pgk pgkParticipant @pgkpgk17461]

I have no idea about the volumes of air you might need but just wanted to say that owning an air compressor and you suddenly find all sorts of handy uses apart from topping up the car tyres – everything from blowing the cr@p off the lawnmower to cleaning out those blind screw threads and running a mister on the mill.

Mine was a cheapo from lidl that does the job but I wish it was bigger. Noisy- yes – but it's possible to fill the tank then lug it elswhere to use… or run a long line. A silent bambi is expensive.

As an out of the box thought… back when i was a kid and my dad used to take us camping he made up an adapter and filled the spare tyre to high pressure at the first garage we passed am and used that to inflate the air-beds come evening and the inner tubes we used when swimming.

pgk

[John RuddParticipant @johnrudd16576]

How about roll your own from a defunct fridge or freezer?

The compressor units therein are fairly quiet, coupled up to a suitable tank to give some volume..

[RobinParticipant @robin]

I was given a compressor because my brother couldn't stand the NOISE. Neither could I.

I now have 2 Bambi's, permanently on and no louder than the fridge, (probably because they use fridge compressors)

[Mike PooleParticipant @mikepoole82104]

We had a storeroom in our workshop that used to be the sound proof room for noise testing Prestcold fridge units. It had a very strange dead atmosphere when the doors were closed, you couldn’t hear apprentices who were locked in either.

Mike

Edited By Mike Poole on 17/10/2018 13:29:56

[Speedy Builder5Participant @speedybuilder5]

Mike, was it silent enough to listen to your heart beating and the blood rushing around your body – Now that was Eerie!!
Ex Vickers Weybridge.

[Robert Atkinson 2Participant @robertatkinson2]

Fridge compressors ar good quiet option but fairly low flow. A few things to watch out for though. They are normally lubricated by oil in the closed system so you need libricator on the inlet. Not a problem with running engines or misters but you also need a cleaner on the tank outlet for other uses.
They are capable of very high pressures if left to run on their own. A pressure relief device on the output is a must.
It is illegal to relese the gas from a fridge so either buy a new compressor or get a qualified company to de-gas the fridge for you.

Robert G8RPI.

[Neil WyattModerator @neilwyatt]

[ALAN STAMMERS 1Participant @alanstammers1]

Don't understand your post Niel, but then again its hard to understand much on this forum

[not done it yetParticipant @notdoneityet]

Anechoic? Silence? Neil does have a wide ranging sense of humour, so it does make some think a bit harder at times.

Edited By not done it yet on 17/10/2018 17:29:55

[Neil WyattModerator @neilwyatt]

It's a sound-proof room 'anechoic chamber' as described above, but a well-known individual in rather famous shot…

[James AlfordParticipant @jamesalford67616]

I use a compressor regularly, quite late in the evening. I bought a "silent" 24 litre Orazi compressor from Amazon for £130.00: they do a smaller one for under £100.00. They are also on E-bay.

It is not silent, quite, but you can hold a normal conversation with ease when it runs. I only have a 14' x 8' garage, but if I am not next to it, I do not always realise that it has fired up if I am making any other noise.

**LINK**

Regards,

James.

[ALAN STAMMERS 1Participant @alanstammers1]

Thank you James, A helpful answer at last, I will look into the Orazi in the morning alan

[Howard LewisParticipant @howardlewis46836]

Direct drive reciprocating compressors are noisy, even small, 1 – 2 cu ft ones.

Belt driven compressors are quieter, because they run more slowly, but tend to be larger displacement, so are almost as noisy.

Diaphragm compressors are the quietest (Having to open up a Bambi, for a repair, found to my surprise that it is a reciprocating unit, although the packaage looks like a fridge compressor with a clamp around it instead of a welded join.

Machine Mart do a range of diaphragm compressors ranging from a single unit upto a triple unit.

Howard

[Douglas JohnstonParticipant @douglasjohnston98463]

My fridge freezer recently packed in and I looked longingly at the compressor, but a quick check on google soon made me desist. As was pointed out above it is too naughty to release the ozone munching gas. I had to part with 25 quid to get it disposed of properly, but I can sleep with a clear conscience. My new fridge freezer seems to use an ozone friendly gas, so if I am still alive when it packs in I might get my hands on the compressor.

Doug

[not done it yetParticipant @notdoneityet]

How do automotive air-con compressors compare with fridge units? Anyone know? Obviously need a drive, for starters.

[Brian Sweeting 2Participant @briansweeting2]

Posted by not done it yet on 17/10/2018 20:24:30:

How do automotive air-con compressors compare with fridge units? Anyone know? Obviously need a drive, for starters.

Price wise a lot more expensive.

A fridge compressor with starter electrics can be simply plugged into the mains to run.

An auto compressor needs a drive motor, motor pulley, drive belt, 12 volt dc supply to operate the drive clutch and special connectors for the pipeline. Overall, more effort, more noise, more space and more money.

[not done it yetParticipant @notdoneityet]

My take on it:

There are plenty of scrap cars out there.

They will require rather more motor power than a fridge unit, so may possibly be able to run at lower speed and lower power – but have a far better output than any domestic freezer unit (about 160W?)

I would expect the clutch, required for a vehicle air-con system, could be short circuited or removed, so a 12 volt supply may not be required.

Pipes and connectors should not be an insuperable issue for an engineer. – the connectors are already there, in the car, anyway, so it just depends on where the lines are cut?

I was hoping someone would particularly have knowledge of the power and speed options. Possibly just too powerful?

[Mike PooleParticipant @mikepoole82104]

Air con units must use a fair bit of power as I believe they disengage with kick down on automatics. I think 5hp has been mentioned.

Mike

[not done it yetParticipant @notdoneityet]

That would be at fairly high engine speed, but they still work at engine idle speeds, too? I have a spare air-con unit available and that made me wonder whether one might be appropriate as a practical quietish unit. Mine is currently a good working spare and I don’t really need another compressor, so I’m not going to try it at this point in time.

[Howard LewisParticipant @howardlewis46836]

Are automotive air con compressors compressing gas or liquid?

The usual advice is to run the air con on the car for about 5 minutes each week to keep the seals lubricated. That suggests liquid rather than gas. Or maybe the refrigerant is below its critical temperature, and when compressed it changes to liquid, and that is what lubricates the seals.

Anyone to enlighten us?

Howard

[Neil WyattModerator @neilwyatt]

My car troubles relate to my air con pump…

The bearings collapsed and it took out the alternator belt.

Got a s/h pump and took it to be fitted and the aircon regassed and… wrong pump.

Next try somehow I had tuesday in my diary and the garage had monday…

Hopefully third time lucky, but I do have a spare pump now…

Neil

P.S I can't see how it would work without a clutch

P.P.S. they work at scary high pressures.

P.P.P.S. I think 5HP is about right, I think they add about 5% to petrol consumption.

[not done it yetParticipant @notdoneityet]

(PS) Dunno about removing the clutch and replacing with a pulley, but not an insuperable problem?

(PPS) The recharge dispenser attachment indicates only 2.75 Bar (40 psi). It is only a matter of boiling a low boiling point liquid and condensing it.

(PPPS) Long ago, 4HP was quoted so 5, nowadays, seems reasonable – but that is at engine and pulley multiplier speeds. Only 5% for a ~100 HP engine? Common rail diesel injection pump pressures are scary!

Not all pumps will be the same capacity – I expect the one I have is for a fairly large vehicle – but I don’t know for certain. Perhaps the pump speed is altered for more or less cooling?

They all have lubricant in them – whether automotive or fridge type. I know of people recharging a freezer compressor with propane. It worked. The lubricant should remain in the pump if they leak on the gas side, but most automotive pumps are emptied and recharged with lube and refigerant, I believe.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 20/10/2018 22:13:18:

Anyone to enlighten us?

.

This should help, Howard: **LINK**

http://www.airconcars.com/html/how_it_works.html

MichaelG.

[Author]

Posts