Alkin W31 - my personal review

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GeneT

GeneT

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Sep 7, 2020
709
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Arizona, United States
This review covers my experience thus far with a 220V, 4HP, 3.7CFM Alkin W31 vertical with the Auto Start/Stop & Condensate drain features.

Cost was $3100 for the basic compressor + $600 for the automatic start/stop and condensate drain feature + $320 for shipment from NJ to AZ with liftgate service at this end (you can save quite a bit by arranging to pick it up at your nearest freight hub, if possible), for a total of $4020. If you're price shopping make sure your comparisons include similar features and shipping.

My Alkin W31 arrived strapped to a pallet, wrapped in plastic, and covered with a cardboard box. The manual and fill whip were bundled with the compressor. Both a User's Manual and a Parts List were included (along with an Alkin catalog). The manual is excellent. Compressor parts, use, maintenance, and troubleshooting are all well-covered. There are a few (very few) places where the English is a little awkward, and the pictures are a little dark, but still crisp. I had no problems understanding the manual, or following the illustrations. Having the 'real thing' in front of you makes up for any lack of resolution in the photos. Missing from the manual (understandably) is anything particular to airguns, as well as instructions for the electrical hookup. More on that in a minute.

Nearly everything about the compressor appears to be high quality. Fit and finish are excellent and all the fittings appear to be top-notch. There is nothing that makes you think any shortcuts were taken. One place where cheap components often hide is in the electrical box, but the Alkin has a tidy box with quality components. I'm impressed!

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My compressor came with a ~8ft cord, but no cord cap (plug). I have seen elsewhere that Alkins come with a 10ft cord, so there may be some variability, or they may be counting the cord all the way back to the electrical box. But mine measured about 8ft from where it's tied to the compressor frame. It's pretty normal for a 220V tool to come without a plug - there are multiple cord caps that you could use, so shipping without a plug means you can install the plug you need. In the U.S. a 220V circuit might have 3 or 4 wires. Four wires are used when the circuit will be broken out into two 110V circuits somewhere on the tool. The Alkin is "true" 220V though, so it uses only three wires. The "missing" wire is the neutral. If your plug style has four prongs, just leave the neutral alone, this is completely safe and not a shortcut or problem. The wires are yellow with a green stripe (ground), brown, and blue. Mine came with a label on the ground wire as that's the one that's important for safety. The other two wires are 'hot' and connect to the two 'hot' terminals of your plug. (If you don't know which terminals on your plug are hot, ground, and (if applicable) neutral you should get someone to help you who does.)

The compressor itself is well-labeled with key information (direction of rotation, oil type, valve and gauge ids). In use, it is loud, but not horribly so. It is probably a little less obnoxious than my shop compressor, but the sound is quite different.

One thing that is a bit odd, to me, is that the start and stop buttons are located almost on the floor. In practice this doesn't really matter, but I find myself mostly kneeling when I use it. It's kind of hard to see, but the silver cylinder is the purifier and near the bottom of it is the purifier valve I'll refer to later.

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The fill valve is a bit different than what you might be used to, and I like it. There's a simple handle for fill and bleed. When I ordered, I was asked what my air tank connection is and so my compressor came equipped with a female Foster fitting - perfect to connect directly to my tank.

Note the valve (swinging handle) and the high quality gauge. Valve is in the 'vent' position.



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My compressor came equipped with the auto bleed and auto shutoff features, set for 4500psi (310 Bar). For me, that means operation works like this:

1. Make sure the purifier (last stage) valve is open and start the compressor. The first time you do this, you'll run the compressor for 10 minutes before closing the valve. The manual isn't specific about subsequent runs, but I'll run it for a few minutes just to get the oil circulating before putting a load on the compressor.

2. Close the purifier valve. Pressure will start building, but due to some dynamic, probably with the purifier, you will not see any pressure appear immediately on the output gauge. After a minute the output gauge will climb, quickly, to final pressure. If you have the auto shutoff feature, a nice little moment of panic awaits when the compressor shuts down and dumps some air giving you the momentary impression that something has gone horribly wrong...

3. At this point I attach the whip to the tank and switch the lever to the 'fill' position. This immediately kicks the compressor back on as it starts to fill the space between the fill whip valve and the tank valve. When the pressure is near max again, I open the tank valve and the compressor continues running until the tank reaches auto-shutoff pressure and the compressor again stops.

4. At that point, I close the valve on the tank, then flip the fill lever back to 'vent' which bleeds the connection between the fill whip and the tank, making it safe to disconnect. According to the manual, this sequence is very important. flipping the fill lever to 'bleed' with the tank open, will push high-pressure air back through the fill/bleed valve potentially damaging some of its o-rings. (Not to mention wasting some of your air!)

5. The system remains pressurized and ready to fill another tank by repeating steps 3 & 4. When finished, turn off the compressor and crack the purifier valve to allow the pressure to bleed out. I leave the valve open, ready for the next fill. If you've used any of the made-for-PCP compressors, the Alkin will impress you with its speed. Note that if you barely open the purifier valve to dump air, it will stop leaking at some point where there is potentially still high pressure in the system. Make sure the valve is opened completely before considering the compressor de-pressurized. Additionally the fill whip will remain pressurized until you flip the fill lever back to 'fill' at which point it will vent vigorously. This is important if you want to loosen the nut connecting the fill whip to rotate it to a better position. That nut, by the way, should only be hand tightened, so if you're trying to loosen it, and it's hard to turn, the whip is probably still under pressure!

Topping up a big tank (what some vendors call 100cuft) the Alkin doesn't break a sweat. The compressor surfaces get warm, but not hot, to the touch.

Speaking of heat, my big bottle is only very slightly warmed by topping up from 250-310 bar. I guess those intercoolers are doing something after all.

I was going to wait to post a review, but the W31 is completely boring - it just fills and fills and nothing breaks, it doesn't stop making pressure, it won't just die for no apparent reason, and it gives no indication that any of that will change in hour 20, 50, or 100.


So that's it. I'll add to this thread in the unlikely event that something does change.

Oh yeah, about that white thing...



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Gene- awesome job in posting this, along with properly adhering to grammar, punctuation, and paragraph structure, so I can easily follow step by step. You can join HUMDINGER one day, and help write compressor owner’s manuals for some of these manufacturers that don’t know how to, ha ha! 

Ive got a question to you, along with fellow Alkin owners that I’ve wanted to ask for awhile, but the timing was never right. I hope you don’t mind me asking on this tread of yours, and hopefully it’ll help others after they do their first oil drain and refill.

Two months ago when I performed an oil change, I noticed if I fill exactly to the mid point of that red dot in the sight glass, when I turn the compressor on the level of oil on the sight glass is almost dang near zero! I know it’s swirling around getting dispersed but I think a little level of oil should still be seen. So I added enough oil just to get me at the top of the red dot, so now when o turn the compressor on I see about an 1/8” level of oil above the bottom perimeter of the sight glass, whereas before there was no oil level shown.



Have any of you Alkin owners found that to be the same on your models?
 
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Bigragu, good question, better to be safe than sorry.

Picture may be worth a thousand words. I have same model as yourself. This is how mine came from the factory. Notice how the oil level is slightly above the red dot indicater. When running compressor the oil level drops to the bottom of the red dot or perhaps slightly below of the red dot. Picture was take with compressor on the level and in the cold state, in other words, hadn't been ran in a few days. There is also an indicater shown as a red line as the oil level, mine also came with a sticker to show max/min. oil level.

I'm supposing the max indicater represents the oil level in the cold state and as long the oil level doesn't drop below minimum indicater when running I feel good to go. My Compressor is new, when I perform my first oil change I will fill between the red dot and the level in the picture and have no worries.

Cheers,

Mike (neighbor across the river from you)

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PS,

Gene, I concur, you did a great job, as usual.

Dang, I made enough edits - between being a terrible speller and these fat fingers on this tiny little keyboard!








 
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2. Close the purifier valve. Pressure will start building, but due to some dynamic, probably with the purifier, you will not see any pressure appear immediately on the output gauge. After a minute the output gauge will climb, quickly, to final pressure. If you have the auto shutoff feature, a nice little moment of panic awaits when the compressor shuts down and dumps some air giving you the momentary impression that something has gone horribly wrong...
Click to expand...


That is due to the priority valve!

It ensures that there is always a minimum of some 150bar~3000psi in the water seperator and that it is working at 100% capacity.
 
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2. Close the purifier valve. Pressure will start building, but due to some dynamic, probably with the purifier, you will not see any pressure appear immediately on the output gauge. After a minute the output gauge will climb, quickly, to final pressure. If you have the auto shutoff feature, a nice little moment of panic awaits when the compressor shuts down and dumps some air giving you the momentary impression that something has gone horribly wrong...
Click to expand...


That is due to the priority valve!

It ensures that there is always a minimum of some 150bar~3000psi in the water seperator and that it is working at 100% capacity.
Click to expand...


Yes, Humdinger straightened me out on that when I first wrote it. I should probably edit in an update.

GsT
 
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I have a 2006 horizontal model, it still runs like it's brand new, the white thing on mine is to hold a scuba yoke fitting, I'm sure Alkin has changed a few things since 2006 , I've heard that mine has a crank shift that's only supported on one side and that the newer one have bearings on both ends, so I hope that's not going to be a issue down the road, also mine makes a knocking sound for the first couple of seconds of start up ,I've read that's normal but it worries me every time I hear it, does your new one make that noise on start up?
 
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