Cheap Compressor Filters

[SurfLung]

Update...
- I realize this subject was not welcome on this forum in the first place. But now with the China Virus raging thru the country it's even worse. For me, it is still unfinished work which I hope to wrap up in just two more postings. I set out to see how well these things work or can be made to work.
- I was trying to do this alongside my restoration of the Tornado/Kidde compressor. But complications and set-backs with the compressor kind of forced me to set this aside until the compressor issues were solved. I think the compressor is out of the woods and so I am finishing up with these filters.
- I have run the compressor and filled a test tank several times thru these filters.
1. The moisture condenser appears to work fine. The humidity in my basement was very low on my first try with this system and I wasn't getting very much moisture condensation in the filter when filling a 42 cf scuba tank. But later I discovered a lot of the moisture had condensed in the hose running from the compressor up to the filter. So, yesterday the humidity in my basement soared to 62 and filling the one 42 cf test tank resulted in a substantial amount of condensed moisture to drain.
2. On the other hand, the original FILTER tube contained only activated carbon (no 13X Sieve) so no further moisture absorption there. I thought about re-packing it with 13X but I don't have any of the blue test strips.
3. Thought about modifying a Lawrence Factor filter and I really didn't feel like doing that. THEN, I discovered I already did it when I modified a LF filter for re-packing to use on my little Aerotecnica MCH-6 compressor. The modification requires it to be a little shorter to fit the Chinese filter tube. Notice I moved the original internal spring to external use.

The media retaining screen is held in place by a snap ring.The mod is on the left and original Lawrence Factor on the right.

- I filled my 42 cf test tank last night through this condenser/filter combination and it seemed to work fine. What I'd like to do is fill it several more times and see if the blue test strip starts to change and how many fills it takes to change as the 13X Sieve soaks up moisture. My little Aerotecnica has a similar 2-tube condensation and filter system that I can compare with.
- When that's done, I'll consider this review finished and post one final update.

 

[CuriousRambler]

Thank you for your concern.
For an air gun application I really like the idea of cadmium plating especially in parts in contact with aluminum, just not in breathing gas applications. Alternatively if I don’t use it then I don’t need to worry what’s going to happen or any health implication even should I decide to lick the coating off with my tongue every day for the next 10 years in gratitude to China for making such a splendid product.

The thread gauge is more interesting, and your right I dont know much but I know what it isnt after tested with both a NPT and NGT stepped thread plug gauge also a standard UK BSPT taper. Now I do understand the differences and the fact that the filter in question had the fitting removed by others prior to the gauge test that may have had an effect on the original thread with the elbow fitting being turned to both seal and for the elbow to position correctly must have adding additional stress or strain to the soft aluminium. At first was thought NPT was the nearest thread,

The alternative NGT thread gauge was used to test if the 3 thread additional minimum effective length difference than the standard NPT made any difference.Granted the test gauges were different in tolerance one was to ANSI B1 and the NGT gauge was to ANSI CGA V1 but the thread being tested fully matched non.
Now I also understand that it is possible that they are manufactured to another thread form ANSI CGA V1 CSAB96 or ANSI B57-1 even to the old NGO thread form but as we don’t have those gauges to test with I cant be certain. Hence the BSPT thread was thought. Again it is possible that they made it to a modified 55 degree Whitworth form, Or with some degree of truncation or with some older or class of ISO 228 G standard. Class A or B was another consideration.

So in conclusion this is a product for cheapskate air gunners who are not going to know or care one thread from another. And on a scale of importance if the customer don’t care why should a manufacturer in China.
Its not like your going to catch a cold with it. So your right I dont know much, I only know what it isnt. LOL

So wait. You personally tested the threads on one of these filters with gauges?

But it's unacceptable for anyone else to get their hands on one to do any testing with it?

I fully appreciate your safety concerns. As someone whose work occasionally has to follow BPVC guidelines, I really respect pressure vessels and their stringent engineering. Nevermind the potential breathing air implications of low grade filters.

I'm also glad safety codes have existed from the beginning of time, and everything your LDS uses in association with their compressor is strictly designed for their purpose. I'm especially happy to know no dive shop has ever fixed any issues with unknown off the shelf parts from the local hardware store. Clearly, thousands would die as a result.

Seriously though, if you're not a fan of it: go away. That's infinitely more valuable than contributing your conjecture and (quite possibly very accurate) unfounded assumptions about what the product is.

I'll ask what's already been asked: have you personally verified the threads are Cd plated? I don't want to hear why you think air gunners don't mind. Yes or no, have you?

You imply that you personally tested with thread gauges, but claim it's unacceptable for somebody else to get their hands on one for testing. What makes you special? How did you come into possession of one to perform your testing? Why didn't you share that information publicly, in a place like this, where people might benefit from the information?

Your posts are tired, and utterly useless in the context of this thread. I'm not suggesting you don't know what you're talking about; I don't know you. You could very well be a professional at these things. I'm not even suggesting you might not be correct. But I absolutely applaud @SurfLung for the efforts, and for sharing the information openly, to inform the public and promote civil discourse regarding the potential cost/benefit.

Share a word of caution, then hope/expect he's aware of the risks. But do so in a civil tone, not an aggressively posturing one. If you're not satisfied, simply don't follow the thread. Repeatedly editing posts with childish snark and trying to bully everyone out of experimentation is simply pathetic.

Edit: P.S. The potential risks associated with getting an inferior quality filter seriously cannot be over-stated. IMO, one of Iain's best points is that of corrosion: just because it works fine this week, doesn't mean it won't become a bomb next week, or 6 weeks from now. The applicable codes do exist for a reason. Just be aware of the risks before you play the game. It could very well be Russian Roulette.

 

[Miyaru]

For my mobile compressor, I needed a filter housing as well and had a look at the AliExpress offered filter housings.
Since I'm usually standing next to the compressor to disconnect tanks when the pressure is highest, I decided to keep looking.

Found this filter housing second-hand:

Since it was a few decades old, I called the hydro-technician. First thing he said: when it's aluminum, don't bother. We won't pressure-test it.
But this one was steel, rated to 350bar, and the technician pressure tested it to 500bar. No issues.

Now look at the filter size, and the thickness of the filter housing.
Which one would you rather stand next to when it's pressurized?

Note: the picture was taken after the filter arrived. It was of course thoroughly cleaned before pressure testing.

 

[SurfLung]

@Miyaru Yes I encountered the "Old Aluminum Filters" issue as well. There is a useful lifetime in the specs of some compressors on how many fills you can do on aluminum filter housings. I think the aluminum flexes and work hardens with each fill... Eventually becoming brittle and less flexibly tough. I actually had a crack in the 3rd stage (HP) aluminum condensation tower of my RIX SA3 which I bought used and is pretty old. I had to buy a new tower and replaced the cracked one. Fortunately RIX still sells these parts. My 1980s era Aerotecnica MCH-6 has aluminum filter housings but it is in almost brand new, unused condition. I'm thinking its the number of fills rather than the number of years but I may be wrong.

On the other hand, my Tornado/Kidde compressor is even older and has STEEL condenser tower and steel filter media canister. But in this case, the media canister is rusted severely and the condenser is just plain OLD technology. I wanted to keep it original but it is so much easier to just get the compressor running right and install a NEW condensation and filter system. BTW - This is the compressor I'm using to test the 2-tube filter system in this posting. So far I have filled my test tank to 2,000 psi 9 times. I want to see how many fills I can get before the blue strip changes color.

Finally, when I bought the RIX SA3, I needed a media filter system and bought a 4 tube filter array that came off an old Olmeva 6000. This filter array is all aluminum and uses the same sized Lawrence Factor filters as the Aerotecnica MCH-6 and MaxAir 35. I don't know how old it is, but I've filled a lot of tanks through it... Some up to 3400 psi. (Note: I bought it from a reputable compressor technician)

So, aluminum filter housings are quite common and well accepted when they're new. But you are on your own and at your own risk when buying them used. Jim Shelden builds new filtration systems at reasonable prices. @rcontrera Sells new Coltri Sub filtration for reasonable prices, too.

 

[SurfLung]

Final Thoughts...
- I hate to say it but, the "Cheap Chinese" Filter System appears to be working very well with my re-packable Lawrence Factor filter modification. First, I think the moisture condenser tube is working as well as (but probably better) than the repair-job we did on my little Aerotecnica MCH-6 condenser. And second, I think the re-packable Lawrence filter is serving well at absorbing the remaining moisture, oil, smells, and tastes. I can't see any way that the air can go anywhere but through the filter media. Compared to the Aerotecnica MCH-6 filter media it seems about the same capacity. The specs in the manual say the Aerotecnica should last for 19 or more fills of 80 cf tanks. This is under fairly moist humidity conditions. I have done 23 fills of my test 42 cf tank and the blue strip has not yet started to change color... But I'm filling less volume and probably drier humidity conditions.
- I think a big part of it is the internal design of the condenser. Look at the drawings showing the insides above. The condenser is capturing a heck of a lot of moisture and oil from the air before it gets to the filter media... Extending filter life. I have breathed the air from a scuba tank and it has no taste or smell. I've also breathed it from just turning the tank valve on and standing in the air stream.
- Here's a BIG Factor: Remember I'm using a Back Pressure Regulator, so there is very good efficiency in the condenser and filtration system. From a purely mechanical perspective, there's no reason why this system shouldn't work as well as it seems to be working.
- Safety Factors: Being manufactured in China, some here have questioned the safety of this filter system. I don't have the capability to test metallurgy, plating content, etc. The threads and O-ring recesses all seem precise and snug. Although my test tank is only filled to 2,000 psi, I have a 2900 psi safety Over Pressure Valve which I have run the pressure up to several times to check the valve. I haven't sent an air sample in to see if the air is officially Grade E breathing quality. But, I haven't done that for my other compressors, either. Yes, I know I should do that.
- So here ends my evaluation of the Cheap (and highly controversial) Chinese Compressor Filters.

 

[SurfLung]

Replying to Questions...
- I received a lengthy private message that brought up some valid points and questions so I thought maybe others had the same thoughts but were afraid to ask.

1. The warranty limits on aluminum filters. I think he said a major compressor company listed 15 years or 50,000 cycles. And he added that the 15 years might be more of a liability issue than the 50,000 cycles... Which makes practical sense to me.
2. He also questioned whether my filling a test tank to 2,000 psi was sufficient to demonstrate the condensation and filtering efficiency.
3. And finally, he didn't see a check valve and PMV (Pressure Maintence Valve) on my system... Which is necessary for condensation and filter efficiency.

Here's my answer:

Testing with 2000 PSI Tanks. I'm a "Vintage Equipment" diver and the tanks I use the most are Navy Surplus 38 cubic foot steel tanks marked 1800 psi. I wear them as doubles and fill them +10% to 2000 psi. This gives me 84 cf of air in a more comfortable, more buoyancy friendly package. These tanks are totally re-qualified with fresh hydro and visual. I have kind of a crappy looking single 38 I have been using to test compressors so that if I get moisture or oil in there its confined to the one tank... Which I can have my hydro guy clean up easy enough.

But my point is that low pressure tanks are alot more common than you might think. 1800 psi is quite common in CO2 for beverage systems, O2 and Argon for welding systems, etc. I'd seen lots of tanks marked 1800, 1880, 2015, etc. These all have the same requirement that you don't want moisture condensing in them.

PMV and Check Valve: I DO have a check valve and "BPR"... Back Pressure Regulator. This accomplishes the same thing as a PMV but is a more versatile... It has been explained to me a few times that the BPR is better than the PMV but frankly I couldn't tell you why. Mine is set to 1800 psi... Which is the setting recommended in my RIX SA3 manual AND, is the default setting when you buy a BPR new with the Bauer label on it.

I have seen guys recommend even higher PMV pressures than the 2030 psi you mention. Supposedly to squeeze every drop of moisture out. I went this route for awhile. Until a friend of mine laid out a more logical approach. Remember both RIX and Bauer spec the BPR to be set at 1800 psi...

If I am filling tanks to 2000 psi, but I set my PMV/BPR to 3000 psi, I am forcing my compressor to work harder than it needs to just to fill tanks to 2000 psi. And, setting for much higher than 1800 psi gets into the realm of diminishing returns. 1800 psi gets the vast majority of moisture into the condenser and the rest is absorbed by the 13X sieve. Why overwork your compressor to save a few pennies worth of 13X Sieve?

 

[PR_SMITH]

I realize this is an old thread, but I found something relevant to the conversation.

I have been looking at a small filter system for my Walter Kidde 4.2cfm compressor. I originally had it configured with a Bauer P21, which now has too many issues and is rather old, so I began looking for a replacement that wouldn't require a mortgage.

I settled on this unit: MCH3-MCH6 Filter Tower Add-On Kit , with the breathing air upgrade(a better filter) At about$310 USD, it's comparable, price-wise to the Chinesium filter kits on Amazon, but from a reputable manufacturer. I just ordered it today.

 

[Ghost95]

How's the filter life on that tower and filter? Are you happy with the performance? Face you had an air test?

 

[PR_SMITH]

How's the filter life on that tower and filter? Are you happy with the performance? Face you had an air test?

I just ordered it yesterday; I'll let you know how it performs once I run it.

I only fill my own hp100's and a set of double 80's, so it should be reasonable for that level of usage.
I will be getting an air test.

 

[Ghost95]

I just ordered it yesterday; I'll let you know how it performs once I run it.

I only fill my own hp100's and a set of double 80's, so it should be reasonable for that level of usage.
I will be getting an air test.

Thanks. Looking forward to your reports. I'm looking at the same thing.