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What fittings can I connect together (building an air compressor) ? Answered

Hi,

I'm building an air compressor out of fridge compressors, propane tanks and NPT fittings from ebay, everything was cool until I received a check valve I ordered before all the other stuff (because it was from another seller so no need for a group order :) for one item).

So I ordered a 1/8 female/female check valve (one way valve), and I measured the diameter with calipers, and it's not 1/8" (3.2mm) but a lot more, which makes sense, 3mm would be really tiny so now I don't understand how all of that works

here are the fittings that will compose the system (those are 1/2 I guess but I will order 1/4 and 1/8 as well to make the complete circuit (around 20 fittings total):

http://www.ebay.com/itm/281299625853

here is the check valve I already ordered (1/8 BSPP):

http://www.ebay.com/itm/182025682762

I also noticed the valve is linear while the fittings appear to be the shape of a cone, will it matter ?

Thanks in advance for any help ;)

Discussions

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nazmo76

3 years ago

Good news,

I ordered a while ago some fittings from ebay to see the quality and stuff, they arrived yesterday and today.

It happens that the 1/8" NPT fit nicely into my 1/8" BSPP check valve (same thread and all), also I have an Italy made paint spray gun that has never been used, it happens that the fitting on it is 1/4" (I tested with one 1/4-1/4 fitting I ordered), all of them fit tightly and the males are not too conical, so I think that with teflon tape it will go nicely ^^

Anyway thanks for all your advice, I'm going to order all the fittings I need (but before I'll talk to the sellers to ask a discount because I will order around 20 fittings), I come back when I get some results ;)

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nazmo76

3 years ago

Sure, but you're lucky living somewhere you have access to the parts directly, I checked the local hardware shop, only metric and expensive fittings available (+ low stocks) so I'll have to buy online

Sure about caution, I bought a 120PSI safety valve (+ I have a regulator and a pressure switch on the way, for safety and... comfort :) )

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Toga_Dan

3 years ago

I often bring the pieces I want to assemble into depot/lowes/ace etc. "How the heck am I gonna do this?". Usually somethin works out.

As kaitlynsdad says, be careful with compressed air. I _think_ a fridge compressor can put out humongous pressures, albeit slowly. You may want a relief valve.

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nazmo76

3 years ago

Ah and also, I'm in France, that's why I'm not familiar with those inches fittings but the Chinese Ebay sellers don't sell tools and fittings in metric...

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nazmo76

3 years ago

The pressures will be pretty standard (9 bars max, probably far less), I saw people using (with success) teflon tape + NPT fittings, the part where it comes unhandy is this BSPP Check valve, I searched for infos about the specs but didn't find anything relevant, so maybe I'll order a NPT valve, just to be sure

anyway, if anyone has some knowledge about the possible compatibility, I would be really interested ;)

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caitlinsdad

3 years ago

Before you take another step, read up and learn about basic pipefitting, fittings and threads.Depending on the pressure you want to build up in your compressor, it will be dangerous with your mix of various pipe threads without appropriate adapters. NPT is the usual standard in North America and whatever the metric and those odd British sizes are... Good luck.