Secondary Filter Stack Advice / Chinese Filters?

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macado

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Cozumel, MX por el invierno
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I'm in process of purchasing a small 3.7cfm electric compressor and I am looking to add a secondary filter stack. The compressor I am buying uses a small P0/P21 type filter which I have been told by many is pretty small. Boston in the summer gets pretty hot / humid, not like Florida obviously but 90 degree high humidity days are not uncommon for us.

My reason for adding secondary filter stack is mainly for redundancy but I honestly just like having piece of mind since I want to make sure I'm also pumping close to Modified Grade E Air (Oxygen Compatible Air). The compressor will be in stored in my relatively cool basement with the compressor intake going out to the basement window to my backyard (relatively clear of running motors / exhaust / etc ).

Currently I am partially pressure blending with regular Grade E air now and I don't really have any issues. I just like the idea of secondary / backup filtration on my personal compressor since I am doing some pretty deep dives. I'll be adding a Nitrox Stick to my setup in the near future as I have helped other friends build them in the past. I've got CO analyzer already rigged up to flow restrictor for testing gas.

I intend to fill the secondary stack with Activated Carbon + Molecular Sieve 13x + Monoxycon (Hopcolite) from Lawrence Factor. I know some people debate if you really need hopcolite but I figure it's good insurance and I could always re-evaluate if I really need it in the future.

Right now I am trying to research smaller filter stacks that would be suitable for this project. I was looking at this secondary filter 16" Filter Stack from Filter Techs. Obviously I don't want anything too massive as the compressor is small and has to fill the stack first. Any thoughts?

PU-530001-AF, Filter Techs

I know in addition to the filter stack I would add a check valve, bleeder/bump and a priority valve to keep the stack pressured to prolong filter. All that fun stuff adds up $$

I know occasionally used stacks pop up online / eBay and I have been looking around.

Currently there is a cheap Bauer filter stack on eBay. Would this be a good deal?
Bauer scuba air Compressor Filter | eBay

Of course in the quest to save money I also looked at AliExpress and found a few Chinese-made filter stacks which are repackable This is the one in question I was looking at. US $79.0 |4500PSI air compressor filter water oil separator absord moisture filter absord water filter on Aliexpress.com | Alibaba Group

Has anyone used one of the Chinese filter with good or bad results? I know that I would still need to add a check valve and priority valve to this unit, bleeder but not sure it's really designed for those things. The Chinese stuff sometimes scares me but I am curious if anyone has used them for secondary filtration or should I stay far far away?
 
Cool. I sent Jim an email. Hoping he might have a smaller stack available that's not listed on his website.
 
Cool. I sent Jim an email. Hoping he might have a smaller stack available that's not listed on his website.

He did for me... I run a MAKO that is 2.4 CFM, and after talking with him, we came up with an appropriate sized one. The one I got from him uses the standard LF Mako cartridge, but he also made me a packable insert to do it on my own, sourcing pads and media as necessary.
 
I have the LF one, works fine and I swap the filters after 12-14 months.

I would not but a used ebay filter stack unless it was in pristine practically new condition. Stacks do have a finite life in pressurization cycles, and can get corrosion or pitting and need to be condemned. Just not worth the risk to me
 
I would pass on that used eBay "bargain" with all the exposed corrosion and also on the Chinesium system. That other one from Filtertechs is one that almost all of us sell and we swear by them. While their price is a tiny bit elevated, that is because they buy from a distributor instead of the guy that actually makes them.
 
https://www.shearwater.com/products/perdix-ai/

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