DIY Compressor Filter and Dryer designs

[maniago]

This is a split off of another thread on compressor air testing. To be clear, I just finished a Rix SA-6 rebuild, but have not started filling tanks with it. I am highly interested in what other Rix owners are doing, but any comment is welcome as this thread ought to be helpful to any compressor owner.

So specifically, wrt pre-and post-contaminent filtering and post desiccant filtering, what DIY designs have you guys come up with?

I'd like to hear about are designs and discussions on what works and what doesn't ie whats your container, stacking order, products used (eg Hocalite, 13x MS, filter pads, SS screens, etal) and where did you get your supplies.

I've read the Oxyhacker bible and only found one partially useful website on this topic.

Thanks for any info!

 

[swamp diver]

Best place for DIY supplies is Lawrence Factor in Florida or you can purchase the same material from High pressure breathing air compressors, scuba air compressors, Scuba air in California.

If you tear apart each company's filters you will find the proportion and type of media varies but in general you have MS 13x, activated charcoal, and catalyst (Hopcalite, Monxycon, Carulite) separated by polyester (LF) or foam pads (Bauer). You'll need a final separator on that RIX followed by the MS, AC and HC. You want coconut-shell based AC as it has less dust and is better at adsorbing VOCs from the ambient air. The HC must be kept bone dry in order to work properly somewhere in the range of -50 C atmospheric dew point.

To do this and to determine when to switch out your filter add an eyeball moisture device with the 10/20/30 % relative humidity disc after your stack and before the PM valve. You can get the device and correct disc from Ray at the link below. Change out your filter when the 10 percent sector has gone from blue to pink (blue is new, pink is extinct) but remember the disc colors are reversible so when you change out the desiccant the disc will eventually revert to blue as long as you have not had free water wash over it. If you are diving in cold water < 5 C you'll also want to change out the MS just as the 10% sector changes to pink in order to prevent free flows.

Have a look at part MM and VIC.
Coltri Sub High Pressure Breathing Air Compressors Supplies from Ray Contreras Sales

Good luck.

 

[maniago]

Best place for DIY supplies is Lawrence Factor in Florida or you can purchase the same material from High pressure breathing air compressors, scuba air compressors, Scuba air in California.

If you tear apart each company's filters you will find the proportion and type of media varies but in general you have MS 13x, activated charcoal, and catalyst (Hopcalite, Monxycon, Carulite) separated by polyester (LF) or foam pads (Bauer). You'll need a final separator on that RIX followed by the MS, AC and HC. You want coconut-shell based AC as it has less dust and is better at adsorbing VOCs from the ambient air. The HC must be kept bone dry in order to work properly somewhere in the range of -50 C atmospheric dew point.

To do this and to determine when to switch out your filter add an eyeball moisture device with the 10/20/30 % relative humidity disc after your stack and before the PM valve. You can get the device and correct disc from Ray at the link below. Change out your filter when the 10 percent sector has gone from blue to pink (blue is new, pink is extinct) but remember the disc colors are reversible so when you change out the desiccant the disc will eventually revert to blue as long as you have not had free water wash over it. If you are diving in cold water < 5 C you'll also want to change out the MS just as the 10% sector changes to pink in order to prevent free flows.

Have a look at part MM and VIC.
Coltri Sub High Pressure Breathing Air Compressors Supplies from Ray Contreras Sales

Good luck.

Super thanks. I have 4 coalescers on the Rix - one after 1st and 2nd, and 2 after the 3rd stage. The 1st stage one will probably prove to be useless, but I have them so that's what I did to start out.

I looked at moisture indicators from other sources, but wasnt super impressed; the 10/20/30s look better...

Also not understanding your reference to the "PM" valve. Do you mean the backpressure/priority valve?

 

[swamp diver]

Super thanks. I have 4 coalescers on the Rix - one after 1st and 2nd, and 2 after the 3rd stage. The 1st stage one will probably prove to be useless, but I have them so that's what I did to start out.

I looked at moisture indicators from other sources, but wasnt super impressed; the 10/20/30s look better...

Also not understanding your reference to the "PM" valve. Do you mean the backpressure/priority valve?

Sorry yes the PM stands for priority maintaining valve or back pressure valve. You need one of these to create sufficient dwell time for the air to contact the filter media.

Many of the high pressure components you see on the various vendors' websites are in fact made by Aqua Environment in California. Pricing is pretty similar across the industry but on the AE web site you can get the application notes for each part like PM valve, check valves, regulators, etc.
Manufacturer of High Pressure Valves & Regulators- San Francisco, California - Aqua Environment Co

 

[maniago]

Sorry yes the PM stands for priority maintaining valve or back pressure valve. You need one of these to create sufficient dwell time for the air to contact the filter media.

Many of the high pressure components you see on the various vendors' websites are in fact made by Aqua Environment in California. Pricing is pretty similar across the industry but on the AE web site you can get the application notes for each part like PM valve, check valves, regulators, etc.
Manufacturer of High Pressure Valves & Regulators- San Francisco, California - Aqua Environment Co

Yup Aqua has a sizable portion of my money already, including the aforementioned priority valve...

---------- Post added February 15th, 2014 at 12:14 PM ----------

Maybe a better question is what is the inside diameter and length of the filter holder you guys are using? I might just convert one of my coalescers to an MS etal dryer instead. I just don't have a clue how much of each chemical is good, esp the MS: 1/2 oz, 10 oz, 100lbs?

My coalescers internal dimensions are ~9"x1"dia. Seems like that should be pretty close to a 12k 10" disposable cartridge in capability, yes? Anyone?

 

[rddvet]

Yup Aqua has a sizable portion of my money already, including the aforementioned priority valve...

---------- Post added February 15th, 2014 at 12:14 PM ----------

Maybe a better question is what is the inside diameter and length of the filter holder you guys are using? I might just convert one of my coalescers to an MS etal dryer instead. I just don't have a clue how much of each chemical is good, esp the MS: 1/2 oz, 10 oz, 100lbs?

My coalescers internal dimensions are ~9"x1"dia. Seems like that should be pretty close to a 12k 10" disposable cartridge in capability, yes? Anyone?

On a side note I have an aqua environment pm unused for sale on cavediver. Thus far no hits. If you need one let me know. I messed around with the open setting on it and them saw the Lawrence factor one and immediately bought one. It is a beast compared to aquas's

---------- Post added February 15th, 2014 at 02:16 PM ----------

On another thought it sounds like you're kind of where I was when I set up my compressor. I decided to buy a used filter stack that Lawrence factor made cartridges compatible with. It's easy as pie. Order a cartridge, drop it in, and you're done. It might not be the ,pst cost effective choice but its really not bad. And much easier than packing and filling filters by hand when all I want to do is fill tanks and go dive.

 

[maniago]

On another thought it sounds like you're kind of where I was when I set up my compressor. I decided to buy a used filter stack that Lawrence factor made cartridges compatible with. It's easy as pie. Order a cartridge, drop it in, and you're done. It might not be the ,pst cost effective choice but its really not bad. And much easier than packing and filling filters by hand when all I want to do is fill tanks and go dive.

Finding a used filter stack seems to be a larger PITA than I expected....

 

[rddvet]

Finding a used filter stack seems to be a larger PITA than I expected....

Try contacting this guy. http://www.ebay.com/usr/bgoo7

His name is Ed. He's very knowledgeable and builds compressors and nitrox sticks for alot of the Fl shops. You will get mixed opinions about him, I think mostly because his family used to own a local dive site. He helped me tremendously building my system and was always honest and forthcoming. He's got tons of filter stacks and whatnot laying around his shop. I would message him through ebay and let him know you were referred by someone who bought through him (ps I didn't buy through his ebay store) and ask if he has a stack to sell you direct. The one I have is an Eagle brand.

 

[maniago]

Ok thanks I'll give him a shout.

On another note for anyone who's bored, this is an interesting treatise on filtration I came across... Filter System Design

 

[KD8NPB]

Scuba Compressor or SCBA Air Fiter Canister 5000 PSI Uses Std Filters | eBay

This is what we use. We use pad retainers, synthetic felts pads, and then hand pack them.

They hold about a quart or so of media.

I'd probably do:

50% MS13X
10% Hop
40% AC

You want to plumb from the bottom up. The 15 micron filter at the end is good in case some of the media weasels past the felt pads.

I suggest mixing some drierite crystals in with the MS13X. It'll give you a good idea of your service interval for your filter.