Electric vs Gasoline Compressor

[mmcmah]

Is the person who made that call still missing?

LOL

Thanks everyone for the great input. So, my takeaways are: Electric compressor for home use, possibly upgrading to a generator and trailer sometime down the line if really needed for remote usage; enough cylinders to dive for a weekend is easier and cheaper; the small high-RPM compressors may work, but aren't designed for continuous usage (> 1hr).

Based on this input, I am revisiting my options and starting to look at larger compressors with an automatic drain and the ability to fill without getting the compressor or cylinders too hot.

 

[mmcmah]

Each stage is responsible for a bit of pressure increase in series, so with four there are four cylinders compressing the gas with each responsible for a smaller part of the increase. This makes getting rid of the heat more efficient.

Maybe you should go back to the original issue, having enough gas for a trip away.

You can do a lot of diving with a rebreather and a 15 (aka ho120) of dil and another of o2 to transfill to the unit’s onboard dil and o2. Skilled people can do a whole weekend on just the unit with it’s two 3s, but taking a couple of extra 3s guarantees two days of gas even for non gurus.

In metric, assuming poor skills such as mine, you may use 50 bar out of a 230 bar 3l of each dil and o2. After three dives you have 80 bar left which is so so for a fourth (I want at least 100 to start from). Then you can squeeze approx 150 bar* 3l = 450l out of the 15, so 30 bar, next day, 120 *3 = 24 bar, etc etc so a good few days before you are down to 100 bar.

This is also much quieter and quicker and less likely annoy the neighbours, hotel, etc.

I would love to explore a rebreather as the solution, but it is too far down the road in timing. I have a few years or more of open circuit still ahead of me.

 

[kelemvor]

everything at work is spec'd in kVA for generators, transformers, inverters, etc. but most people have no idea what that is and kW is a bit easier to explain, especially when portable/home generators are spec'd in watts/kW not in kVA

must be a "commercial" model thing. My generac generator is rated in watts. It has a big sticker on it that proudly proclaims 10,000 watts. I've always disliked VA ratings. Tends to be misleading to most people who are used to dealing with the watt and wrongly assume it's the same thing.

 

[iain/hsm]

LOL

Thanks everyone for the great input. So, my takeaways are: Electric compressor for home use, possibly upgrading to a generator and trailer sometime down the line if really needed for remote usage; enough cylinders to dive for a weekend is easier and cheaper; the small high-RPM compressors may work, but aren't designed for continuous usage (> 1hr).

Based on this input, I am revisiting my options and starting to look at larger compressors with an automatic drain and the ability to fill without getting the compressor or cylinders too hot.

I'm not too sure about this we have only scratched the surface.

No to the auto drains from me. Waste of time waste of money, besides the small size of compressor your talking about whats the point?

You fill the cylinder, then when full while keeping the compressor running you turn off the cylinder drain the separator tower/s while changing the cylinders over, then close the drains, open the 2nd cylinder and so on. The bigger portables are perfectly well suited for this type of operation.

Now the auto drains, the type we are talking about have a sub 1 mm oraffice flow hole for the high pressure side, they block with a speck of dust let alone emusified oil and water junk. When they do work they are new and when they dont your screwed as when they open nothing comes out and you blisfully flood the zeolite tower with water until the compressor goes into hydraulic lock.

Consider the bigger pump sizes that the filling time equates to the separator drain time
15 to 20 minutes as opposed to the 20 - 30 minute filling rate, or use bigger separator towers

 

[mmcmah]

Indeed, @iain/hsm . That's a really good idea and saves the expense and maintenance / point of failure(s) for the ACD.

 

[iain/hsm]

Another important consideration is the spare parts cost and availability for the brand you choose.
On cost the Bauer spares are difficult to work out what your getting for the money and this 500 hour and 100 hour spares kit is a total rip off when you consider that a 500 hour kit for the JuniorII is double the cost of the same spares kit for the Capitano. Further the Capitano would have filled almost twice the amount of cylinders in that time.
Also its gone to retail dive shop supply so add those margins to the cost

Now for most (New) buyers 500 hours on a Junior II is around 250 fills ( Lets make that 1000 single cylinder fills or two filling cycles of twins ie 4 fills 2 hours per per day) and on average about a 5 year life.
Average divers life span in the sport is 3 years So sell it before you need to service it and it becomes someone elses problem just dont leave it on the yacht over winter for rust. Plenty of retail outlets you can obtain pricing from.

Rix are the only suppler who publish an individual full spares price list and list what is in each of the spares kits.
You cannot find a published public spares price list for the L&W, Coltri/Max Air.

 

[iain/hsm]

You have also to all bare in mind that the portable scuba compressor market is not designed for divers.
Added to the fact that the design remit is to design the compressor set as light as possble,
So high RPM with light weight high stressed aluminium components, hottest allowable gas temperatures,
before cooling, highest compression ratios you can get away with the shallowest (lightest) oil pan you can
cook the lubrication in is all part of the requrement for a lightweight product.

New product buyers base choice on lightweight design nice colour armed with the single question to the nice boy of girl in the dive shop of "how many tanks will it fill" you get the picture of the sort of product your considering.

 

[Couv]

500 hours on a Junior II is around 250 fills

Two hours per fill?

 

[iain/hsm]

Two hours per fill?

Haha yeah thanks for that, Engish maths is different to you lot I guess LOL
From the OP's earlier post I got he was filling doubles twice 2 hours run time per session with the duty rating issue made earlier.

the time it would take to fill multiple cylinders and doubles.
@Miyaru)?

Then I re hashed the reply. Note to self, read your replies and count properly Ive just corrected it.