What filter cartridges should I use? Two 32" stacks for a 6 CFM compressor

[tmassey]

It's spring, when a diver's thoughts turn to... compressor maintenance!

I've got some questions, so I'll start separate threads for each. This one is abut replacing the compressor filter stacks. I also have questions about oil changes, as well as startup/shutdown procedures.

A bit about my compressor: 6CFM Poseidon PFU-150. It's a 5HP, 3-stage compressor with a block made by Bauer. It doesn't have an oil pressure gauge, so I assume it's splash-lubricated. It's got a single two-part moisture separator, plus a moisture drain in the filter stack on the back of the compressor. It's supposed to have auto drains, but it leaked pressure so I've removed it and simply use three needle valves with tubes to drain the water. Past the compressor I have a fill board with a large single-part gold Bauer separator (which is always bone-dry, of course) and another 32" filter stack, then the back pressure regulator (set to 2000 PSI) and out to my tanks.

Now, filter stacks: I have two stacks. The first is mounted at the back of the compressor, and is the one farthest upstream. Its cartridge is a Lawrene Factor X546223, which seems to make the stack a "Lawrence Factor 54 Series". It's a 2-part "cleaning" cartridge with 13x and Activated Carbon, and it's 2.75" x 23.5". More details: X546223 – FILTER TECHS

Downstream of this is another filter stack. Its cartridge is an August Industries 1603M (I believe: it's written in fat marker...). It too is a 2-part "cleaning" cartridge with 13x and Activaton Carbon, and it's a *different* measurement: 2.75" x 27". Its filter strip is completely blue. More details: Filter Cartridge for MAKO PD-1603 - August Industries Inc.

It seems I have two 2-part (AC+13x) cartridges. So far, I've never failed to pass OCA testing, and I have CO monitoring in-line with the compressor. But even so, I think I'd rather have a 3-part cartridge with CO catalyst (hopcalite). The indicator strip on the upstream LF cartridge is completely tan, so I figure it's time to replace it. The question is: with what?

It seems that there are four cartridges for the upstream LF stack: AC only (X542223, $65), 13x only (X546723, $64), 13x and AC (X546223, the one I have, $66), and AC, 13x and Hopcalite (X542423, $91).

The downstream stack seems to be a "Mako 65-series" that takes 27" cartridges. I'm *guessing* that any Mako 65-series cartridge that is 27" long will fit properly -- for some reason, the model number of the *stack* seems to change based on the type of media in the cartridge. I'm not sure of this, though, so please correct me if I'm wrong. If I'm right, then there's a variety of cartridges for this, too. The most interesting are: AC only (PD-1203, $61), 13x only (PD-1503, $53), 13x and AC (PD-1603, the one I have, $65), and AC, 13x and Hopcalite (PD-1803, $72).

So, I have a couple of questions:

1) So, what should I be looking at purchasing? Some say that the upstream could/should be just drying (13x) and the last should be a 3-part cartridge. But given the difference in price (which is minor) and the fact that I've got *WAY* more filtration than I have any need for, does it matter? Is there a disadvantage to simply putting a 2- or 3-way cartridge in the upstream and a 3-way in the downstream?

2) Realistically, how often and in what order should I change the cartridges? The cartridges themselves say that the maximum useful life is six months. Given that the cartridges are stated has having a 26 *thousand* cubic foot capacity, that's about 70 hours of compressor time *per* *cartridge*. In six months, I won't put 20 hours on them *total*. I've used this set of cartridges for two years so far and am still getting OCA out of the compressor. So what is a realistic life for them?

Thank you very much for your help! I appreciate it.

 

[tbone1004]

most of the oiled compressors have at least the final stage as splash lubed. You likely have an oil pump on the first couple of stages and may be able to find a port that has a plug or somewhere you can put a T with a gauge on there if you want. If you're doing that I would make it a pressure switch though so it cuts the compressor off it it gets low for whatever reason.

The solenoids for your auto-drains should be able to be rebuilt quite easily if you want to put them back on.

Your filters should be "in order" since the expensive stuff is what is water sensitive. I'd make the first stack purely a coalescing filter to dry everything really well which gives your second filter the best case scenario to scrub everything out. First cartridge would be 13x only or potentially 13x and AC. Then second would be AC and hopcalite. Don't have the LF catalog in front of me to see which series those are, but you can get the Mako filters from LF.

On frequency, I'd let the strips and gas analysis do the talking. The biggest thing that kills filters for time is getting the water out of them. Keep the water out and you can get a LONG life from them. I know several people that have active cooling on their coalescers that can go 2-3x the rated cubic footage of the filters and still have OCA coming out. They tend to change it just for feel-good factor than anything needing to be changed.

 

[tmassey]

The solenoids for your auto-drains should be able to be rebuilt quite easily if you want to put them back on.

I wish it were that easy. It's a weird autodrain. It's got four drains in one with a single solenoid. I've taken it apart. The o-ring sizes are odd, and I can't find documentation on it. I do wish I could get it taken care of, but I think it's a little too advanced for me. As little as I run the compressor, manual has been survivable.

Your filters should be "in order" since the expensive stuff is what is water sensitive. I'd make the first stack purely a coalescing filter to dry everything really well which gives your second filter the best case scenario to scrub everything out. First cartridge would be 13x only or potentially 13x and AC. Then second would be AC and hopcalite. Don't have the LF catalog in front of me to see which series those are, but you can get the Mako filters from LF.

If I were starting from a blank slate, I would agree. But given that I have a filter stack built into the compressor chassis and I'm not messing with that, and my filter board was originally designed to be used with a Coltri MCH-6 (hence the extra separator), I'll live with the order. Basically the extra separator is superfluous: so be it.

I've never had someone recommend full 13x in the first stack and *no* 13x in the second. I get the concept: allow a ton of space for AC and hopcalite, seeing as you have an *entire* filter for 13x. I've never seen an AC/hopcalite cartridge. I'll go looking... (I think I'd lean toward AC/13x for the first stack: it's still a ton of 13x, the extra AC has value too, and it would be sufficient filtration by itself if I wanted to eliminate the filter board.)

On frequency, I'd let the strips and gas analysis do the talking. The biggest thing that kills filters for time is getting the water out of them. Keep the water out and you can get a LONG life from them.

I'm certainly endeavoring to... I'm trying to intelligently minimize cost without risking safety. It's a tough balance. Especially because gas testing only tells me there's a problem *after* I've been breathing the stuff at depth......... But as little as I use the compressor, I can't simply replace/test everything all the time: I'd be paying $30 per air fill! The compressor isn't *that* convenient!

 

[Wookie]

I won’t say much about filtration, but on my makos, the first filter is always ac only, a PD1503, and the second filter is the PD 1803, with all the good stuff.

Shoot us a picture of your autodrain. What you’ve described is a mako. Gold anodized with a single cover on the valves?

 

[tmassey]

A thread I started about it when I got the compressor has lots of details, including photos. Feel free to reply here or there.
Can you identify this coalescer and auto drain system? Trying to rebuild.

 

[Wookie]

A thread I started about it when I got the compressor has lots of details, including photos. Feel free to reply here or there.
Can you identify this coalescer and auto drain system? Trying to rebuild.

Yup, I see that now, and I’ve never seen anything like it. Fun project though. For you....

 

[tbone1004]

@tmassey no reason not to have some 13x in the second stack, but no real reason to have it if your first stack is full of it. Just food for thought, but there's no point in going alternating media. You want to go in series with it and the dryers are the most important, well technically the coalescer before the filter is the most important, but you get the point.

 

[rjack321]

If it were me... I would use 13x + AC in the first and 13x+AC+hopcalite in the second stack.

Since you aren't even close on the hours/capacity issue I would replace them every ~18months. They are "supposed to" be replaced annually but going to 2 yrs seems like penny pinching to me. I'll pay a little more for peace of mind.

 

[tmassey]

Yeah, under $200 for both stacks every 18 months is hard to complain about. Actually, 18 months = 2 years for me: I can't run during the winter, anyway. Throw away in fall, buy new in spring = 2 years.

It so happens that that is exactly how long I've had the compressor -- perfect! I'm right on schedule!

I understand the logic of some of the above filter choices, but it also creates logistical and configuration issues. If I were tearing this thing apart and rebuilding or setting up from scratch, I can understand highly optimizing the filter cartridges, etc. But the way it's set up now should be thought of as internal compressor filtration and external "hyperfilter". They're not next to each other, and they're not *going* to be able to be next to each other. It may not allow "ideal" filtration, but c'mon: I'm throwing away 20%-used cartridges every 18 months anyway.

But I will keep this in mind if volume noticeably increases.

Seeing as I've been getting OCA tests so far *without* the hopcalite *and* I have CO monitoring, I'm not real worried about not having it if I were using just the internal stack. But it's just as easy to get it in the last stack, so I certainly will.

Thank you all very much for your feedback. I appreciate that I'm taking off a little bit of my *extremely* high filter capacity by putting some logistical reasons first. And I appreciate the feedback on filter life. I think 18 months (assuming the humidity strips show lots of capacity) is a pretty decent compromise.

 

[rjack321]

I think 18 months (assuming the humidity strips show lots of capacity) is a pretty decent compromise.

The problem with the LF humidity strips is 1) you cant see them in real time use and 2) they are activated at 40% RH which is way too wet. Probably not a big deal if the only the first one is partially changing. But for cold water you want that 2nd one totally blue blue. And a final RH in the 10-20% range.