Looking at buying an Alkin W31 - Any advice?

[macado]

Speaking with Alkin today an option for an extra $1000 is to upgrade from the P21 to a P41 filter stack…I’m going to do that for sure when I order.

I did not know that was an option but I honestly think it's a very good idea. My secondary filter tower uses 10" filter stack with an X65240 filter with FilterTechs. I run it in-line with my with the primary filter tower on the Alkin and have another Priority Valve (Backpressure Valve) right after the filter tower before it goes into my mainfold.

According FilterTechs..

The X65240 will process 10,000 c.f. of Air as long as the Air inlet temperature going into the Filter tower is 80 (F)

The Air temp entering into the Filter tower will generally be about 10 - 15 degrees hotter than the ambient temp the compressor is operating in. So if the ambient Air temp is 80 then your Filter tower inlet temp will be between 90 - 95.
This will reduce the capacity by about 70%. So instead of 10,000 you would get about 7,000.
If it’s hotter than that you may only get half the the total.

Edit: filter stack size.

 

[GetDownScuba]

Do you have pics of your setup that you can share, Macado?

 

[macado]

My panel is kind of messy but this is the general layout. Nitrox Stick goes into compressor air intake. It's 1' diameter hose which I have kept as short as possible to minimize resistance.

Compressor Output -> Check Valve -> 10" Secondary Filter Stack -> Bleeder -> Priority Valve (set to 2200psi) -> 5 port manifold > 2-3 DIN Whips or 2 DIN Whips and Secondary O2 Analyzer with DiveSoft flowmeter.

Everything is using Parker QC fittings so I can unplug and move things around. Same fittings I also use on my booster.

 

[GetDownScuba]

Very nice! Everything outside?

 

[macado]

Very nice! Everything outside?

Yeah. It's all sitting in a shed that is attached to my garage. I had my electrician run a dedicated 240v 40amp circuit to the garage/shed for the compressor.

It does get a bit hot in the shed in the summer so I try to fill during early morning or at night when it's less humid, if possible. I do run large fans to try to help circulate fresh air which may be overkill. In the winter I have a small block heater attached to the compressor to warm up oil crankcase when it's below 40f (~4c) and I run a small space heater on timer with an automatic shutoff in there a few hours before.

 

[GetDownScuba]

Truly outstanding and inspiring.

 

[ELCAM]

I did not know that was an option but I honestly think it's a very good idea. My secondary filter tower uses P41-sized cartridges with an X65240 filter with FilterTechs. I run it in-line with my with the primary filter tower on the Alkin and have another Priority Valve (Backpressure Valve) right after the filter tower before it goes into my mainfold.

According FilterTechs..

Yours may be more of a P31 system (10” filter size).
I believe the P41 are the same diameter but 18.5 in length. Either way an awesome upgrade considering a secondary filter tower would cost the same.

 

[macado]

Thanks! Good catch. I wasnt sure what equivalent Bauer sized cartridge was but I just looked it up and you're correct.

Yours may be more of a P31 system (10” filter size).
I believe the P41 are the same diameter but 18.5 in length. Either way an awesome upgrade considering a secondary filter tower would cost the same.

 

[Scubadoo1]

Delete

 

[rob.mwpropane]

Just to add, from talking with guys with a lot more experience on here and elsewhere filter life has a lot less to do with humidity and way more to do with temperature. And as @macado said, it's not ambient temp that dictates filter life, it's the temp that actually reaches the filter which will be 10-15f above ambient (Bauer I believe states there charts @ 18° rise). No matter what, 100% humidity reaches the filter stack, but the cooler the air the less humidity available.

I just run my compressor only when it's cooler out (I shoot for 60F or less, but no more than 70F max). If it's humid I bleed the coalescers more often.

It was by far the best thing I've done for diving. No more waiting, driving, waiting, short fills, bs. I dive way more now then I ever did, fills are the cost of diesel fuel, and O2 is cheap.

Here's an awesome spreadsheet made by another SB'er (@rhwestfall ??). for filter life. I use it all the time, it's been awesome to see where I'm at.