Small compressors...?

[Genesis]

Doesn't your Alkin have one already? Normally the HP separator is between the output and the media stack so one priority valves serves them both. Or am I missing something?

You are

There's a separate condensator on the SECOND STAGE outlet (third stage inlet), but the final filtration has the condensator/filter stack built into one. The condensator isn't even really a condensator as you think of it - the HP air comes into the filter stack and condensed water/oil goes to the bottom, where it can be drained out. The fitler media entrance is at the top of the cartridge; it is a double-pass (flow down and then up to the outlet) design.

 

[The Curly One]

Geninsis, I have a new model in, the W31E. This model has auto-drains on the second AND third stage water separators, pressure switch to start and stop at desired pressures, pressure maintaining valve and gauges on all stages. www.alkinusa.com Curly

 

[WVMike]

Is it realistic to use a small compressor such as the W31 to fill cascade bottles?

Airtex website has storage bottles, how long would it take to fill the 4000 psi bottle, and would I need to be there the whole time to dump condensation?

How long does it take for a W31 to fill an AL 80 from 500 psi to 3000 psi?

I am thinking of filling a bottle and taking it to the dive site, vs taking the compressor, is this feasable?

Thanks for your input

Mike

 

[WVMike]

May be a dumb one, but then the dumb question is the unasked one right?

If I have a 4500 psi storage bottle with 444cf , could I expect to fill five al 80 tanks from this if it isnt hooked to the compressor?

In other words does it deliver 4500 psi for the total cf stored, or does pressure go down as cf goes down?

 

[Genesis]

Figure 3cf "real" performance over time for that compressor, since you need to dump condensate. (I own one!)

So divide 444 by 3cf, assuming the storage is empty. Or about 2-1/2 hours to fill that bottle.

And no, it doesn't stay at 4500 psi

However, of course when the pressure gets lower the entire thing isn't empty, so refilling it doesn't take as long.

The "smart" way to use storage is to set up a cascade; that is, you fill from the first bottle until the pressure gets too low, then you partially fill from the low pressure one, and top from the second, etc.

Doing this you can get quite a few more fills before the second bottle gets too low to top off. If you have THREE bottles you get even better efficiency, but of course you can turn on the compressor any time and fill 'em back up.

One thing to be aware of, and this is very important, is that you must insure you NEVER contaminate that storage (e.g. forget about the filter change intervals!) because once contaminated those bottles are a BIATCH to clean. Tumbling something that side is not going to be easy.

 

[The Curly One]

No Problem, in fact I sell many of the large storage bottles with those compressors. The ALKIN W31 is the ONLY portable compressor factory approved for filling cascade systems and for running up to 8 hours non stop. Now I think if you have to run one that long then you probably need a bigger compressor but the ALKIN can handle it if required. Many of my Paintball customers run the compressor all weekend long during big tournements and we have not had any problems. No other portable can handle that.
Every ALKIN compressor is tested non stop for 15-20 hours on a test jig. Then they change the oil and put it on the frame with the motor it is to be shipped with and tested again for about 1 hour. When I get them I install the American standard plug, test it quickly and include some paperwork. So when you get the compressor it is tested, full of oil and ready to run.
As far as performance goes the ALKIN puts out more actual CFM than one of the competitors that advertises 4.3 SCFM**. All car, motorcycle, compressor and most everyone else uses their best performance figures in their advertisements but I have no idea where some of these people come up with their figures. Some are not even close.
I usually give a discount on all the storage bottles, hoses, fittings and regulators when purchased with a compressor.
Every other compressor dealer if you try to order a cascade system with one of their portable units will immediatly start trying to talk you into a $6000+ compressor because they know it can not handle it. The ALKIN can and does and you even get a discount on them.
The thing I like about the ALKIN compressors that no one else even comes close is how quiet they are. You can talk in a normal tone of voice when filling tanks and you standing right over the compressor, try that with ANY other brand. Note: If you get a gas model our gas Honda motors are just as loud as everyone else's. Curly

 

[pescador775]

Genesis is correct. The backpressure valve should be placed on a condenser upstream of the final filter. The chemical media in a filter function as a molecular sieve, and do not depend on higher concentrations of pollutants for efficiency. In fact, it may impair the filter. If Hacker is accurate regarding what he has heard from Bauer I doubt that Bauer has thought this through. High concentrations of pollutants gradually degrade the filter media resulting in progressive loss of filtration. They rarely go bad all at once. Reduction of concentrations entering the final filter are beneficial to filter life and air quality. To this end, the pressure chambers of the filter and condenser should be separate physically and by pressure gradient.

I'm editing this while adding a final thought. In some cases, a condenser may be followed by a combined condensator or condenser/filter like the Bauer PO. Should this be so, a backpressure valve should be placed on the condenser and the combined condenser/filter, eg, two valves.

 

[Genesis]

with single, final units are hosed.

MOST smaller units are built this way - their final stage condensator/filter is one unit, like the Bauer P0 or the Alkin W31's final tower.

It would be nice to have a separate condensator in front of the final filter. If I put in a couple of bank tanks I will probably also add auto unloaders (and do it myself; its not THAT hard to do with a couple of air-operated pilot valves, one low-pressure solenoid valve and a timer) and also install an off-cabinet filter unit which has a filter tower, and use the existing one as simply a condensator. Not hard to do - just install a deflector/sieve element at the inlet of the cannister, remove the existing element, and that'd pretty much do it I suspect.

 

[pescador775]

That should do it. The auto dump valves that I've seen operate off the first stage. Usually, there is a 'T' which taps off low pressure air and runs from there to a pressure operated valve or other device. I've also seen electric types which auto dump when max pressure is reached or when the unit is shut down. Appropriate check valves are sometimes needed. I'm not really into all that stuff but that's what I remember from observation.

 

[Genesis]

The first stage only runs 50-60 psi (I have GAUGES on all of my stages - I put 'em on, 'cause I like to see what's happening)

That goes to a regular solenoid valve, energize to hold closed, 100% duty cycle.

The first stage tap goes to the pilot valves for the second and third stage.

When you want to unload, or when you turn off the compressor (e.g. final pressure switch) you dump the power to the solenoid for a couple of seconds. This causes the pressure at the first stage outlet to collapse; the consequence of this is that the other two coalescers unload.

A short-period timer circuit can "pulse" the LP line; a few tenths of a second is enough, since IDEALLY you don't want to dump all the air in the condensators, just the water. Most commercial systems dump for WAY too long, IMHO.

There is no need to run high pressure air around if you mount the unloaders directly on the condensators - only the pilot air needs to be piped around.