compressor for sailing

[Genesis]

I have one, and its just a final safety device more than anything else.

For the price difference between buying gas and filling my own, another buck a tank or so for the HF stack time is not material to the equation. My cost is about 30% of the LDS cost around here, and that includes the HF stack time.

I've never had a drop of water (or oil) in a tank, nor in the HF stack when I open it to replace the cartridge. I do, however, get both in the separator/stack on the final output stage (its designed as both a coalescer and filter holder.)

The only crap I've ever had get into a tank was from a commercial shop that gave me some really nasty-tasting gas once. It aborted the dive - I don't know how bad it really was, but if I can taste it, it's bad enough that I don't want to be breathing it.

 

[Bob3]

... gave me some really nasty-tasting gas once.

I watched WATER run out of the fill whip at a place [sports shop] I had my tank filled at once. I was so speechless I couldn't even chew the guy's butt.:wacko:
I did manage to pass the word & my tank was probably the last one "filled" at his place. Small towns were at least good for that. :mean:

 

[iain/hsm]

Re your compressor running in hot climate, on a boat. Regardless of the brand you buy, being able to service the unit yourself on deck or at least being able to replace the stage pistons, heads and liners would be an advantage. Get a good spares kit and a full "workshop manual" with the unit, not the customer owner manual, these only tell you how to operate the pump and tell you to use an "authorised repair centre".

The full workshop manual has all drawings and a complete parts lists. Price up the wear items (before you buy the compressor) and ask the saleman how long each part will last.

To reduce your running cost use the stainless repackable filters that only need filling with chemical, remember in hot climates your filter life may be reduced to even nine hours per pound of filter chemical. Also use one of those high pressure visual indicators ($60) that turn a card inside a small 1/2 inch plastic viewport from blue to pink when wet, very useful, they work up to 5000psi. Get one that shows 20,40, and 60% humidity.

Try not to use the compressor in a heavy swell, some makes use splash lubricant from the crank to lubricate the upper cylinders. On a boat an oil "slosh" can flood the upper heads and "ruin your day" or use an oil less compressor pump. Same with the separators in a swell the collected oil/water can migrate into the next stage inlet and if its the final stage your chemical filter is ruined with water.

 

[oxyhacker]

I was thinking about building my own condenseate autodrain system until I ran into a guy who told me that his factory one has blown up his compressor twice, by failing to drain enough, allowing the water level to get so high that it got into the next cylinder and water-locked it, doing major damage.

Pescador's system, the oversize coalescor, makes a lot of sense, if you think about it, being completely passive. I think the reason why it isn't used more often is that the big systems need an active drainage system, and there just isn't enough money in the smaller ones for people to worry about it. Also getting a reasonable sized sump in the coalescor requires either a stack that sticks up higher or hangs down more, awkward in a portable system.

BTW, I lucked into an old Bauer Utilus recently. Its' only 3.5 cf or so but, like your Alkin, bigger than the little portables, but turns only half as fast. I'm surprised how much more I like it - it's just about the perfect compromise machine - small enough to still be portable, but for the extra 40 lbs or so one gets a much quieter, cooler running machine that seems Good deal (though I think the next step is to build a REALLY tiny exclusively portable machine, ala Pesky, if I can only find one of those 4 stage Kiddes instead of a 3 - I saw one on Ebay with a chain saw engine!).

Genesis once bubbled...
Larger condensators would permit less frequent dumping, which in turn might allow a closer-to-rated-delivery to be actually realized. I am considering adding larger ones, along with a home-made auto-dump system (not difficult to do with air-controlled pilot valves) as I'm thinking of putting in a bank here, and dumping by hand is a pain in the tush if you're filling a bank.

 

[pescador775]

One of my dive buds has owned a Utilus 10 for some time, a previously owned unit that he bought on my recommendation for $1200. Last year, I pulled the heads and entire third stage for routine inspection and replacement of the valves. I was impressed by the overall quality of the machine. The entire thing is light alloy in contrast to the old iron beasts like the early Capitano and Purus. Apparently, it has splash lubrication. I saw no sign of a high pressure oil line or regulator as in the Capitano. The #2 and 3 cylinders are horizontal unlike the Capitano which has V shaped arrangement. The oil spray is fed to the third stage plunger by a channel in the sleeve and evacuated by a drain hole. This particular compressor has had substantial use but appeared ready for another 10 years of service.

 

[oxyhacker]

Bauer's big vice is that they make too many models, and use way to many names to describe them. There are actually two Utilili, apparently, the Utililus 3 (now upgraded in to the Utilus II) and the Utilus 10. Best I can figure out the 10 is basically an early Junior, splash lubed and fast turning, and the 3 is a smaller version of the Capitano - 1200 rpm and pressure lubed. That's what I have.

Little mystery about these old midline Bauers, in that they came in a 3200psi and 4700psi version, and the only difference was the filtration system housings. But when I ask Bauer if I could raise the output pressure if I was updating the filtration they freak out saying the machine is too old. I got to wonder if that mean the 4700psi machines of my compressor's vintage have all blown up, or just that they don't think its fair to expect an old compressor to learn new tricks. Though several old time compressor men have told me they don't think any of the 3 cylinder compressors are true HP machines.

pescador775 once bubbled...
One of my dive buds has owned a Utilus 10 for some time, a previously owned unit that he bought on my recommendation for $1200. Last year, I pulled the heads and entire third stage for routine inspection and replacement of the valves. I was impressed by the overall quality of the machine. The entire thing is light alloy in contrast to the old iron beasts like the early Capitano and Purus. Apparently, it has splash lubrication. I saw no sign of a high pressure oil line or regulator as in the Capitano. The #2 and 3 cylinders are horizontal unlike the Capitano which has V shaped arrangement. The oil spray is fed to the third stage plunger by a channel in the sleeve and evacuated by a drain hole. This particular compressor has had substantial use but appeared ready for another 10 years of service.

 

[Genesis]

happily pumps right up to the 4250 psi blow-off.

No BS, no problem.

That looks pretty good from where I sit....

 

[pescador775]

Hacker, yeah, I guess I am one of the conservative old timers referred to. We used to think that a four stage was necessary for high pressure service. However, it is evident that the three stage can be designed to do this competently. I can't prove it but I suspect that the only difference between the 3000 and 4000 psi Bauers are the pressure ratings of the condensators. In any case, the old Capitanos had an aluminum inter separator, an inverted steel tank for a condenser and a combined separator/filter with charcoal. The steel tank was rated about 230 bar. When the old tank rusted out I replaced it with a 300 bar version. Also, I adjusted the relief valve to 3500 psi for the new PST HP's that I was filling. It will probably go higher but I'm not under any 'pressure' to do so.

Yes, the old Utilus was a baby version of the Capitano. The Utilus 10/Junior series are lighter and generally cheaper to manufacture, a good compromise, and improvement, over the original Utilus and Purus which the series replaces.

The lightest weight, highest output, 3 stage compressor ever built is the MIL surplus Cornelius/Stewart Warner. The pump itself weighs only about 20 pounds and is designed specifically for direct drive which saves a lot of weight over belt drives. The output is a true 4 cfm @ 3500 psi. Personally, I wouldn't run this compressor over the rated psi, certainly not to 4500 psi since the burst disks in cylinder 3 and in the SW condenser would probably pop. These are a unique size and not easy to find. On the other hand, the little 4 stage Kidde, an equally old design, can be run to 4500 without problems. In tests, I've seen them go to 9000 psi; rumor says they will blow at about 10,000 psi.

 

[pescador775]

I selected an old but reliable 5hp B&S engine to power the four stage Kidde compressor assembly. My reasoning was that 5hp should be just enough for a pump of that size. After all, a 5hp will drive a 3.5 cfm with room to spare so it should handle a 4 cfm (with less margin). However, tests of the complete assembly indicated that the 5hp was not quite strong enough. The problem is not with the engine which has low hours and is in excellent condition. As I belatedly discovered, and discussed above, the Kidde is actually a 4.5 cfm pump. Reading more carefully, the MINIMUM output specified by Kidde Aerospace tech manual is 4.0 cfm. So, the maximum rpm I can squeeze out of the B&S is 3530 rpm but the Kidde is rated 3750 rpm. To spare the engine I limit rpm to 3400 giving 4.1 cfm actual, 4.1 cfm @ STP inlet conditions (69F-sea level).

 

[The Curly One]

I like the new Entec Briggs & Stratton motors better than the Hondas now. I have used them a few times lately and they start first pull every time and run good. Curly