Home Compressor suggestions

[Waterskier1]

Hi guys,

I’m resurrecting this thread as I learn more. I’ve decided that a small gas powered compressor is what I want. While I'm still hoping to find a good deal on a used one, the local diving season is just about over for Colorado so I'm not in a hurry, I’m also looking at the Coltri MCH6 (about $2900 new + $100 shipping) and the Alkin W31 Gas($3100 - $3300 plus $175+ for shipping) Thus the Alkin is about $300 - $500 more than the Coltri, from the ads I have found.

The Coltri comes with manual drains (not a problem for me - I think the Alkin is the same). The Coltri ad says it comes with a back pressure regulator, inlet snorkel, and special filler valve that has a shut off and bleed. The ad implies that these are usually extra cost items. Are these not standard on most new compressors like I’m looking at?

I’m also looking at the Alkin W31 Gas. Their ad states that it is the only portable compressor factory approved for filling cascade systems and multiple tanks. It also states that it’s the coolest and quietest since it runs at 1200 rpm (less than half the Coltri‘s 2800rpm). It also says it has a 5000 psi max (4600 psi working) pressure versus the 4500 Coltri. But what seems to be an important difference is the Alkin “purifier” is refillable. The Alkin ad also says it has intercoolers between stages and moisture separator between 2nd & 3rd stage. It also says it has interstage safety valves, and discharge safety/relief valve. Does this serve the same purpose as a back pressure regulator but not adjustable? The Alkin website says the Gas W31’s are 3-stage, and the Electric W31 is 1-stage. I think this must be a misprint?? Aren’t the W31 compressors the same, whether powered by gas or electricity?


The Alkin is 3-stage, versus the Coltri being a 4-stage. Is this an important decision factor? I am assuming the additional stage is what allows the Coltri to run at a lower rpm? Is there any other benefit/drawback to the number of stages? The Clotri is spec’d at 90 lbs, where the Alkin is 112-113 lbs. That 22 lbs is only important in moving it around, i.e., loading it in the truck or ski boat (while the boat is on a trailer, gunnels over 6-ft above the ground), and moving from the ski boat to the houseboat on the water. After it’s where it is, the 22 lbs difference would not be an issue. It is very unlikely that the compressor would ever be transferred directly to the houseboat (eliminating the intermediate ski boat) since there really is no place to bring the houseboat to a dock that has shore easy shore access, except the public launch ramp, and that is usually full of trailerable boats.


But I think filtration is my biggest concern and may be the decision breaker. I don’t want to rule out continuous blending of NITROX in the future, but I can’t see that I’d ever take the mixing stick portable. I know that larger external filters are much more efficient, and that might be a consideration for home use, but, again, I can’t see taking a bunch of external filters with me on the boat. So, is one of these significantly better in the filtration department than the other? Can external filters be hooked up more easily or less costly on one versus the other, while easily switching back to the original configuration filter when it goes to the boat? How long do the original equipment filters last? It looks like you can get $20 refill kits for the Alkin ($15/each in quantities). I’m not sure what the Coltri filters cost, and it doesn’t seem they are refillable. I’m not sure the different filters last the same amount of fills either. And, I guess I’m assuming they yield the same quality air in the end – right?

 

[Isaac-1]

It is my personal view that there are no BAD small compressors on the market today, some may be better than others, some just may be better than others for certain tasks (there is a message thread on the scubaboard explaining why a RIX is not a good choice for nitrox, due to its lubrication system, etc.). IF you are going to use it as little as was stated in the original message (less than a dozen tanks fills per month), I see no problem with the small filters these compressor ship with, as you will likely need to change them based on age before they expired from use. Adding adotional filtration later can be done in a number of ways, I think Lawrence Factor even offers a stand alone filter tower that can be connected to a small compressors flexible fill whip .

Ike

 

[rcontrera]

The Coltri ad says it comes with a back pressure regulator, inlet snorkel, and special filler valve that has a shut off and bleed. The ad implies that these are usually extra cost items. Are these not standard on most new compressors like I’m looking at?

Neither Coltrisub nor Alkin delivers the compressor standard with a "priority valve" as a standard item. Inlet snorkels are also not "standard" but recommended for gasoline powered compressors

It also says it has interstage safety valves, and discharge safety/relief valve. Does this serve the same purpose as a back pressure regulator but not adjustable?

No ... safety valves are just relief valves and do not act as a priority valve. The back pressure (priority) valve is designed to maintain a high pressure in the outlet filter to increase the density of the air. This greatly increases the efficiency of the filtering system.

The Alkin is 3-stage, versus the Coltri being a 4-stage. Is this an important decision factor?

Not really. Three stage compressors of comparable output rating just weigh more than four stage due to bigger pistons.

So, is one of these significantly better in the filtration department than the other?

Both companies use Lawrence Factor filters as the standard. LF makes good stuff.

Can external filters be hooked up more easily or less costly on one versus the other, while easily switching back to the original configuration filter when it goes to the boat?

Absolutely! The standard compressor filter will give Grade E air in a well cared for compressor. But adding additional filtration is easy!

How long do the original equipment filters last?

Standard filters will give about 40 standard 80 fills. I am not sure how many fills come from the "fill your own" systems but I assume they are about the same.

 

[Hoosier]

Alkin auto drain option comes with a priority valve.

Stock PO filter only lasts 10 hrs. And it is notorious for a wet fill.

An additional filter is a "must have" item. There is no exception.

You have a repackable canister with 32inch chamber. It is a compact, even you can go around with it. Mine is potable.

In addition, search the previous threads. It has been covered so many times on the board...


Good luck...

 

[WVMike]

Alkin auto drain option comes with a priority valve.

Stock PO filter only lasts 10 hrs. And it is notorious for a wet fill.

An additional filter is a "must have" item. There is no exception.

Good luck...

I have an Alkin W31, does anyone have an auto drain on this compressor and how well does it work?

I had "wet fill" problems with mine, There was a recall on the LF filter cartridges, I think they were packed backwards. With the replacement cartridge I just got 20 hours out of it. With pre recall filters, 10 hours was the norm.

The Alkin uses the filter canister as the final water seperator, how does the auto drain option account for this?

I am looking at the additional filter for mine, would you replace the existing filter system to use this, or add the additional filter system after and in line with the existing?

Adding it after would give you the original filter and final seperator feeding the additional seperator and filter. Does this work?

I want to add a cascade system, but current set up, having to drain every 10 minutes does not make this feasible.

 

[IndyScott]

Alkin W31 ,We need a group for this compresser!!
who has the best price on filters?

 

[Hoosier]

who has the best price on filters?

YOU!!..

Just repack it by yourself. It only takes 10 min and the cheapest option.

 

[Hoosier]

I have an Alkin W31, does anyone have an auto drain on this compressor and how well does it work?

I had "wet fill" problems with mine, There was a recall on the LF filter cartridges, I think they were packed backwards. With the replacement cartridge I just got 20 hours out of it. With pre recall filters, 10 hours was the norm.

AD works great. I don't need to drain it by myself every 10~15 min. When you need to fill up a cascade or a couple of double sets. It really saves your times. And, you can set up the max. pressure so it automatically shut off the power. So, you know when the compressor will be stop.

The Alkin uses the filter canister as the final water separator, how does the auto drain option account for this?

There are two outlets. One of them is from the bottom of the filter canister.

I am looking at the additional filter for mine, would you replace the existing filter system to use this, or add the additional filter system after and in line with the existing?

NO. Just add the 2nd chamber after the stock PO filter, don't replace it.

Adding it after would give you the original filter and final separator feeding the additional separator and filter. Does this work?

I regard the original filtration (PO) as the pre-screening step. Even though it used to be wet, it helps to sort out all large and dirty particles. And, the 2nd chamber do a right job.. When I repack PO filter, I put AC and MS, but if it is wet, AC didn't work, either. So, I am thinking about only filling with MS.



Just my 2 bar...

 

[rcontrera]

When I repack PO filter, I put AC and MS, but if it is wet, AC didn't work, either. So, I am thinking about only filling with MS.

I would always include the activated carbon in any breathing air filter design. While it really doesn't do much for drying the air, it does a great job of removing odor and taste. Dry air can still stink or give foul tastes and nobody wants that. Pure Molecular Sieve is only advised in paintball use.

 

[Hoosier]

I would always include the activated carbon in any breathing air filter design. While it really doesn't do much for drying the air, it does a great job of removing odor and taste. Dry air can still stink or give foul tastes and nobody wants that. Pure Molecular Sieve is only advised in paintball use.

I think you misunderstood my point here.

My point is that as long as there is 2nd chamber (MS-Hopcalite-AC or MS-AC), I had better put PO stack only for MS. I have put MS-AC on PO stack for the redundancy, but I doubt that it is working efficiently because it is easily soaked within 10 hrs.

IMHO, 2nd chamber is a "MUST HAVE" component for Alkin31 compressor. Otherwise, your air will be wet eventually.