Air Couplings with CO2- Why are they leaking?

Hi folks. I bought this and this:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34705
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93104

Both are Central Pneumatics. I'm trying to use them as a CO2 Manifold.

When i plug the "male" part into the "female" part, it leaks CO2 like crazy....not a slight leak, but a big massive huge leak. I tried hitting it with 40 psi, and 10 psi....it won't seal. Only way I can make it seal is to pull on the collar on the female part, (to retract the ball bearings), and push the male part until it bottoms out and stops leaking...

Am I missing something here? Should there be o-rings on the male parts? I figured since they are the same manufacturer, they should work.

There are different styles of the male part....maybe those just don't work together.

They could just be crappy, I guess.

Also, compressed air is typically used around 100psi, maybe they only seal at higher pressures.

shortyjacobs said:

Hi folks. I bought this and this:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34705
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93104

Both are Central Pneumatics. I'm trying to use them as a CO2 Manifold.


I figured since they are the same manufacturer, they should work.

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they are the same brand, but probably not the same manufacturer... being air couplers used with a compressor, they probably consider some leakage as acceptable since they're used with an unlimited source of air..

but, if you haven't figured it out already, much of harbor freight's products are junk to begin with... you really do get wht you pay for.

I use a similar QD on my setup and it doesn't leak.

I could see "some leakage" as being acceptable, but we're talking a full blast....like ruffle your hair at five paces blast....

Probably missing the seals on the females. Some one might have liberated them in the store.

The problem with HF air parts is that they are cheap-- not inexpensive: cheap. They are 'good enough' for air use but frequently their tolerances are poor.

there CHINESE!!!!!!!!!!!!!! what do you think red china has to offer us? or perhaps your using a 3/8 short in a 3/8 long female. if it can be inserted more than 1/8" past the lock its the wrong one.

I have had repeated problems with the HB air line QD's and I have only used them for compressed air and never for CO2 for this exact reason. The HB fittings are generally crap. It's hit or miss on these QD's. Some will seal well and others half assed or not at all. I am familiar with the different types and it's not a mis-matched issue. I've totally given up on using them even for compressed air. They are a major PIA and will somtimes spontaneously uncouple for no apparent reason. I would never trust them for use with CO2. I only buy things from HB that are either for one time use or that I can be reasonablly confident that whatever it is won't self destruct before I get my money's worth out of it. It's unlikely something like a plastic tarp will fail. Someone once suggested never buy anything from HB that has more than one moving part or a power cord. I tend to agree with that. I do have a bench top 8" Chinese drill press from HB that I am happy with. I'm out a whopping $69 if it quits on me. No big deal. It's a disposable tool IMO.

By HB do you mean Harbor Frieght?

While almost everything Harbor Fright carries is Chinese and all of it is low quality product, I dont' have a particular problem with things made in china. I have many things in my home that are very high quality that are made in China. (Odds are you do to-- startign with the computer you are viewing this post on).

Chinese supplies are no different than any other supplier in that they deliver exactly what they are asked to deliver and what Harbor Frieght asks for clearly is the cheapest stuff that can still be called 'tools'.

Yes, HB = Harbor Freight in my post. Don't get me wrong. I own lots of Chinese made stuff. I also love their food and fireworks. It's not a nationality thing, it's a HB thing. There's plenty of crap manufactured right here at home in the United Snakes. I also love my cheapo Chinese drill press. My Chinese made refractometer has more than paid for itself in reliability and convenience.

Hmm....so best guess is I'm hosed, with a slight chance of owning "short" male couplers and "long" female couplers. eh?

I CAN push the coupler about 1/8" past the lock point while holding the collar back....I don't know if that means they are mismatched or not...nothing on the packaging or HB's site hinted at "long" or "short"...

Here's a suggestion: count all the couplers you use. Go somewhere that sells high quality air tools and buy a complete new set of couplers there.

One thing that might be happening is the mixing and match of different brands of couplers that were made to slightly different tolerances. Sticking with a single high quality brand might solve your issue.

kornkob said:

Here's a suggestion: count all the couplers you use. Go somewhere that sells high quality air tools and buy a complete new set of couplers there.

One thing that might be happening is the mixing and match of different brands of couplers that were made to slightly different tolerances. Sticking with a single high quality brand might solve your issue.

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Thanks kornkob, that was my plan for today....it's only 3 couplers, so could be worse, but I need the male couplers to have FPT threads, which don't usually come in nice cheap bulk packs....

Think Lowes is high quality enough?

shortyjacobs said:

Thanks kornkob, that was my plan for today....it's only 3 couplers, so could be worse, but I need the male couplers to have FPT threads, which don't usually come in nice cheap bulk packs....

Think Lowes is high quality enough?

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Buy them through McMaster Carr. I wouldn't trust Lowes either.