I've read the older threads, but was wondering if any current W31 owners have advice on what to look for (i'm buying used) and what to expect (as far as components/filter life, upkeep, etc.)
TIA
-Dave
TIA
-Dave
Looking at buying an Alkin W31 - Any advice?
- Thread starter GetDownScuba
- Start date
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If you are running a dive shop, a used Alkin w31 is not going to keep up with needs. I would look at a w32 at least.
W31 is a phenomenal machine for the price point and for a home filler, but it isn't going to run day in day out.
OP
Thanks. No shop here. Independent instructor that fills a few hundred 80s throughout the year
Gotcha. Should be ok for a few tanks here and there. What year is it? They made some nice improvements around 2019. Pretty decent machine after that.
Got one with bigger filter, filter made for the W32, and 4 fill hoses. Alkin's customer and technical services are awesome. Looking at getting another one, with wheels soon.
I own an Alkin W31 for my personal fill station. It's a great little compressor but I agree with Tracy, if I had to do it all over again I'd get the W31 ~4.9cfm model or a W32. The little ~3.5cfm is great for personal use but when I am filling a lot of doubles it can be painful. There are times when I would really like to fill faster 
The good news is I never have to leave my property and sit in an hour of traffic to get to dive shop. It's an incredible time saver and and honestly it's done more for my enjoyment of diving than any piece of gear I've ever bought.
I bought new mid-2019 and it now has 230 hours on it. So far the only maintenance I've done is regular oil changes and filter changes.
Full disclosure: I did have 2 issues. The 240v to 12v transformer on mine failed (broken wiring/ bad contact) but Alkin shipped me a new one overnight. Also the pneumatic valve on my autodrain was sticking closed but that's more general maintenance. It was very easy to service myself. Aydin at Alkin W31 was super responsive. Sent me instructions and walked me through everything although it was all pretty self explanatory.
Based on hours I pump about 12,000-13,000cu/ft of nitrox 32 a year through it with a blending stick. Not a whole lot compared to most dive shops but it has treated me well. I almost never pump air as almost all of my local diving is on a rebreather or 32%.
One last thing I will say is their hours rating on their filter cartridge is a little bogus. I think it says something like 50 hours in the manual. It's a small P21 type cartridge which Bauer rates for something like 10 hours at 20c/68f. You should be changing this out every ~10-20 hours depending on temperature / humidity. I'm not sure where they got the 50 hour number from. I also added a larger secondary filter stack to my compressor as I wanted to make sure I was pumping very dry and clean air.
Although the Alkin comes with a repackable filter cartridge and you can save money by refilling with your own 13X + Activated Carbon + Hopcalite. I use third party cartridges from FilterTechs. I just find it easier and saves me time. I hated repacking their filter.
filtertechs.com
filtertechs.com
I use the X22629 cartridge as my secondary filter stack already has Hopcalite in it so that my primary filter functions more as a dryer but if I didnt have a secondary filter then I'd probably recommend using the X22249
The good news is I never have to leave my property and sit in an hour of traffic to get to dive shop. It's an incredible time saver and and honestly it's done more for my enjoyment of diving than any piece of gear I've ever bought.
I bought new mid-2019 and it now has 230 hours on it. So far the only maintenance I've done is regular oil changes and filter changes.
Full disclosure: I did have 2 issues. The 240v to 12v transformer on mine failed (broken wiring/ bad contact) but Alkin shipped me a new one overnight. Also the pneumatic valve on my autodrain was sticking closed but that's more general maintenance. It was very easy to service myself. Aydin at Alkin W31 was super responsive. Sent me instructions and walked me through everything although it was all pretty self explanatory.
Based on hours I pump about 12,000-13,000cu/ft of nitrox 32 a year through it with a blending stick. Not a whole lot compared to most dive shops but it has treated me well. I almost never pump air as almost all of my local diving is on a rebreather or 32%.
One last thing I will say is their hours rating on their filter cartridge is a little bogus. I think it says something like 50 hours in the manual. It's a small P21 type cartridge which Bauer rates for something like 10 hours at 20c/68f. You should be changing this out every ~10-20 hours depending on temperature / humidity. I'm not sure where they got the 50 hour number from. I also added a larger secondary filter stack to my compressor as I wanted to make sure I was pumping very dry and clean air.
Although the Alkin comes with a repackable filter cartridge and you can save money by refilling with your own 13X + Activated Carbon + Hopcalite. I use third party cartridges from FilterTechs. I just find it easier and saves me time. I hated repacking their filter.
Bauer Breathing Air Filter W5-9183 X22249
The X22249 Bauer Breathing Air Filter is guaranteed to match the fit and performance of the W5-9183 OEM cartridge.
filtertechs.com
Bauer Cleaning Air Filter 057679410, X22629
The X22629 Bauer Cleaning Air Filter cartridge is guaranteed to match the fit and performance of the 057679410 OEM cartridge.
filtertechs.com
I use the X22629 cartridge as my secondary filter stack already has Hopcalite in it so that my primary filter functions more as a dryer but if I didnt have a secondary filter then I'd probably recommend using the X22249
@macado has been answering lots of questions I’ve had on Facebook messenger and I’m looking to get a W31 4.9cfm model in the next couple of months. 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 own an Alkin W31 for my personal fill station. It's a great little compressor but I agree with Tracy, if I had to do it all over again I'd get the W31 ~4.9cfm model or a W32. The little ~3.5cfm is great for personal use but when I am filling a lot of doubles it can be painful. There are times when I would really like to fill faster
The good news is I never have to leave my property and sit in an hour of traffic to get to dive shop. It's an incredible time saver and and honestly it's done more for my enjoyment of diving than any piece of gear I've ever bought.
I bought new mid-2019 and it now has 230 hours on it. So far the only maintenance I've done is regular oil changes and filter changes.
Full disclosure: I did have 2 issues. The 240v to 12v transformer on mine failed (broken wiring/ bad contact) but Alkin shipped me a new one overnight. Also the pneumatic valve on my autodrain was sticking closed but that's more general maintenance. It was very easy to service myself. Aydin at Alkin W31 was super responsive. Sent me instructions and walked me through everything although it was all pretty self explanatory.
Based on hours I pump about 12,000-13,000cu/ft of nitrox 32 a year through it with a blending stick. Not a whole lot compared to most dive shops but it has treated me well. I almost never pump air as almost all of my local diving is on a rebreather or 32%.
One last thing I will say is their hours rating on their filter cartridge is a little bogus. I think it says something like 50 hours in the manual. It's a small P21 type cartridge which Bauer rates for something like 10 hours at 20c/68f. You should be changing this out every ~10-20 hours depending on temperature / humidity. I'm not sure where they got the 50 hour number from. I also added a larger secondary filter stack to my compressor as I wanted to make sure I was pumping very dry and clean air.
Although the Alkin comes with a repackable filter cartridge and you can save money by refilling with your own 13X + Activated Carbon + Hopcalite. I use third party cartridges from FilterTechs. I just find it easier and saves me time. I hated repacking their filter.
Bauer Breathing Air Filter W5-9183 X22249
The X22249 Bauer Breathing Air Filter is guaranteed to match the fit and performance of the W5-9183 OEM cartridge.Bauer Cleaning Air Filter 057679410, X22629
The X22629 Bauer Cleaning Air Filter cartridge is guaranteed to match the fit and performance of the 057679410 OEM cartridge.
I use the X22629 cartridge as my secondary filter stack already has Hopcalite in it so that my primary filter functions more as a dryer but if I didnt have a secondary filter then I'd probably recommend using the X22249
View attachment 791270
OP
Thanks Macado and everyone. I’m going to take the plunge and get the 31. Tracy, it’s a 2021 with low hours. I’m considering setting up a cascade but will try direct fills for a bit and see how that goes.
It is nothing special. It is one I built. Very similar to most DIY nitrox stick plans. Works great. The only major things I've changed in my design is I've added Solberg silencing filter on the top. I also have a ~45psi / 3bar OPV on the O2 welding regulator as a failsafe to prevent a massive amount of O2 going into flowmeter in the event of an IP creep. I keep the welding regulator set around 30psi.
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