Vacuum and High Pressure Pump

About: I am a teacher who enjoys environmentally responsible woodworking. Most evenings will find me in the shop working with my now 8 year old son Shay who is both my greatest helper and biggest fan.

Intro: Vacuum and High Pressure Pump

Introductory primer on converting a refrigeration pump into a high pressure air compressor or vacuum pump.  If you are planning on doing this you need to evacuate the refrigeration unit in a responsible way.  That is beyond the scope for most people.  I would look to appliance repair places for a pump.  They have to evacuate anyway to dispose of old units removed from customer's homes.  Tell them you are wanting to build a vacuum pump. Cash talks.

You also must heed my warning on using a pressure cutoff switch and an over pressure protection valve.  I can not stress this enough.  Left on and running with no protections this pump could generate over 400psi, way beyond the rated pressures of most tanks, piping and hoses.  If you do not have over-pressure protection it is a bomb.  Oh and NEVER use pvc piping, even if it says it is rated for the pressures.  When if fails because of age, defect or impact it send out shrapnel.  Use hard copper or rubber or other rated lines.  I have been hearing of people using pex water line to run less than 150psi air.  That might be worth looking into.

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    8 Discussions

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    mr fat

    4 years ago on Introduction

    Brilliant work! I have upcycled a refrigerant compressor as a vacuum pump and I had never thought about the other side

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    hohum

    4 years ago on Introduction

    thanks for posting, might you have plans towards making a unit for air brush? fitting with a tank and shut off valve? how would I do that? what might an estimated cost be?

    great instructable.

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    Chris Logan

    4 years ago

    To clarify..... 400psi is noisy. An actual hand grenade explodes with 150,000psi of force. ...... Wear safety glasses.

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    antagonizer

    4 years ago on Introduction

    I'd be a bit concerned about soldering that reamed brass fitting to the copper line. It'd be a lot safer to use a compression fitting, or if your compressor is running 1/4" O.D. tubes, then first solder some 1/4" I.D. tube over top, then add the compression fitting.

    2 replies

    So it isn't the soldering itself that bothers you but that I drilled the brass? Strength issues? I guess I could see that. I soldered it with the line all but flush. Hopefully it is essentially fused, one with the steel line and not subject to the pressures on its own.

    Pretty much. I make working air compressors with fridge compressors and even did an instructable on it a while back. Soldering 1/4" copper to brass can be tricky, even for larger pipes, whereas compression fittings actually hold better as pressure increases. Kind of like a Chinese finger puzzle, if you know what I mean.

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    VadimS

    4 years ago on Introduction

    Nice. I have a larger scrawl compressor sitting in a box. Not sure what I'll do with it, though this is an option. Soldering to steel is fine, just harder to do (need a good flux).

    1 reply
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    NelsonStudiosVadimS

    Reply 4 years ago on Introduction

    Well that tinner's flud seemed to work great I got a very good bond but I have no idea where one would go to get it.