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Author: Subject: A further fridge pump question....
International Hazard

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[*] posted on 21-8-2019 at 16:53
A further fridge pump question....

Firsty to clarify, in refering to fridge pumps i think we are generally referring to 'squirrel cage motors'.
So my question relates to my air compressor, which is a dentist/bank variety that has a squirel cage motor atop a small holding pressurised holding cylinder that outlets into some filters (oil, water).
These compresors run oil that i assume covers and coats the internals and is largely immiscible with the fluid ordinarily being compressed, which is air, and is rudimentarily seperated from it before leaving the compressor.
The compressd air accumulates into the cylinder whereupon water, present in the air condenses into the bottom of the cylinder, requiring routinue removal, oil not effectvely seperated out also accumulates here and must be replaced from time to time.
If properly cleaned and suitability/compatability assesed in regards to gasket, rubber,oil and flange materials within the pump/compressor there is no reason why any gas connot be fed into the air intake of this unit and compressed safetly.

So my question is, is that last paragraph largely true?

Basically can i use it to compress hydrogen and does anyone have any clear advice regarding this. I have done much reading on this, im very familiar with this gases strict requirement not be compresssd with any oxygen present, requiring flushing and bleeding cycles.
Im after the 'yeah ive done this and watch out for...' style of advice please.
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draculic acid69
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[*] posted on 21-8-2019 at 22:32

I don't know about compressing H2 using a fridge pump but I do remember Cody's lab did a video on compressing H2 and it detailed how he separated O2 from the H2 .it was a pretty simple setup involving jars beach balls and catalytic converter honeycombs.and as far as fridge pumps go I've tried to use them from recovered fridges and at most out of four attempts I've only got one to turn on for like two minutes before it stopped for whatever reason.with the price of harbor freight vac pumps and aspirators I'll never try another fridge pump.

[Edited on 22-8-2019 by draculic acid69]
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International Hazard

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[*] posted on 22-8-2019 at 03:45

if the system has no oxygen (there are a few steps to do this) you are pretty safe with hydrogen. if you want to compress oxygen, on the other hand, you can't use a compressor that uses oil, it can go boom

feel free to correct my grammar, or any mistakes i make
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International Hazard

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[*] posted on 22-8-2019 at 04:01

A hermetic and semi hermetic refrigeration compressor is fine for compressing hydrogen, you do want to aggressively filter and clean the out let gas, best to do this after cooling.

Then run through your drying stack to final storage if storing any amount you want 316L stainless steel, starting from a check valve into the main header of your piping system, all pipes should be 316L as well.

Dental blowers (I would not call them a proper compressor) are ill suited for such use.

Newer compressors you will need to thoroughly clean and replace their oil with a mineral oil as the current oil will become acidic on exposure to moisture.

[Edited on 22-8-2019 by XeonTheMGPony]
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