Belt Drive Compressor Possibilities

[rlloyd]

Hi,

I am about to leave on a year long sailing trip. The boat has a 60 HP diesel inboard. Anyone know if it is possible to run a SCUBA compressor off a belt from the diesel...ever hear of anyone doing it?

Or is it possible to run a compressor off the 12/24 volt DC electrical system? I see a Cornelius compressor on Ebay which says 24 volt but every SCUBA compressor I have ever seen is attached to a generator

Would love to fill my own air but I don't think I can afford the space or expense of a new gas powered unit.

 

[veriqster]

the cornelius units are SLOW and low pressure (~2200), plus parts are quite a problem with them. look for the compressor group on yahoo, there's plenty of info in there regarding those units and not only.

 

[rcontrera]

Sure it is possible. I had a very clever customer that used one of my little MCH6 machines and built a cool assembly that included an electric clutch so that he could turn it on and off with a flip of a switch. He mounted the filtration on the bulkhead away from the compressor and used a long hose to fill tanks out on deck. There are a few problems that you have to overcome.

1. You have to pull the compressor off the base and build a support mechanism on the engine
2. You have to direct cooling air at the compressor to keep from overheating
3. You need to pipe in the inlet air so that you don't take a suction of any hot/dirty air from the engine compartment
4. There needs to be a "set" speed for your engine to keep the compressor running in it's range. Ours is 2400-2800 rpm. Getting it right may require playing with pulley sizes.
5. You need to install an automatic condensate drain on your filter system so that you don't have to climb down into the engine compartment every 10-15 minutes.

Hope that helps!

 

[Isaac-1]

Given you seem to be talking about a sailboat with a 60 hp diesel, I assume it is in the 40+ foot range. connecting a compressor directly to an engine is a major under taking, and easier option is likely to get a 3,000 - 5000 watt inverter powered from your house battery bank and use an AC powered compressor assuming your boat does not have a generator. You should be able to find a smaller 2.5-3 CFM 115 Volt AC compressor powered by a 2-2.5 HP electric motor which would fill a standard 80 cu ft tank in about half an hour. Assuming you have 500-600 AH battery bank this would allow filling of 2-3 tanks before you have to recharge using the high output alternator from your main engine still keeping your batteries at that magic 50%+ range to extend life, for that matter you could possibly run the compressor while running the engine, assuming a 170 amp HO alternator, it would almost keep up with the compressor draw.

Ike

 

[rjack321]

Hi,

I am about to leave on a year long sailing trip. The boat has a 60 HP diesel inboard. Anyone know if it is possible to run a SCUBA compressor off a belt from the diesel...ever hear of anyone doing it?

Or is it possible to run a compressor off the 12/24 volt DC electrical system? I see a Cornelius compressor on Ebay which says 24 volt but every SCUBA compressor I have ever seen is attached to a generator

Would love to fill my own air but I don't think I can afford the space or expense of a new gas powered unit.

Get a used gas powered compressor.

The real cost is the compressor, "not buying" the little 5-8hp gas engines on a portable unit aren't going to save you any money. In fact, the plumbing and installation of a compressor in your engine room will easily cost 3x the ~$150-250 you save by avoiding the gas power.

Pumping you own breathing gas is not really someplace you want to cut corners lest you build an permanent anesthesia machine.

 

[Isaac-1]

I was suggesting electric for the keep it simple reason, a gas powered compressor would mean carrying a gasoline supply in addition to the diesel for the main engine. Running a gasoline engine on the deck, extra concerns with fresh air snorkel CO contamination concerns. An electric compressor could probably be mounted in a cockpit compartment if it were water tight, and ran with the cover open to provide cooling air circulation (if need be you could add an automotive type electric cooling fan for boosted air circulation)

 

[rjack321]

Ya but a 5,000W inverter is not going to start anything.

To start the smallest electric compressors is going to take something in the ~8,000+W range - you might as well buy a gas powered compressor for those costs.

 

[veriqster]

Hi,

I am about to leave on a year long sailing trip. The boat has a 60 HP diesel inboard. Anyone know if it is possible to run a SCUBA compressor off a belt from the diesel...ever hear of anyone doing it?

Or is it possible to run a compressor off the 12/24 volt DC electrical system? I see a Cornelius compressor on Ebay which says 24 volt but every SCUBA compressor I have ever seen is attached to a generator

Would love to fill my own air but I don't think I can afford the space or expense of a new gas powered unit.

If you have the space and the weight carrying capacity something like this
16KW 1 or 3 phase 277/480 Single Bearing SAE # 4 /7.5 - eBay (item 160338500515 end time Nov-24-09 13:10:47 PST)
might be an option as well. It could power most of the 3 phase units available on the market (cheaper than 1phase) and would give you plenty of options regarding other commodities (a/c, fridge, etc).there's plenty of ways to accomplish what you want but i think the most affordable would a gas powered small compressor or one of the Cornelius units running off your bank / alternator. the later would be quite unreliable unless you get a spare compressor unit and use low pressure tanks. a small gas powered compressor could be converted for a reasonable price to diesel power by changing the engine and pulleys.

also, talk with James at Shelden Sporting Goods Inc. - High Pressure Air Compressors, he might give you some options as well, like belt driving a Kidde 4.2 cfm unit via an electric clutch (they require 3hp so it's doable via an "automotive a/c type" clutch).

Bottom line, there's plenty of options and regardless of what any and / or everybody says you will have to choose what suits YOU best based on budget, space availability, weight carrying capacity, personal technical / mechanical expertise, etc.

 

[Isaac-1]

Ya but a 5,000W inverter is not going to start anything.

To start the smallest electric compressors is going to take something in the ~8,000+W range - you might as well buy a gas powered compressor for those costs.

I have to disagree with you on this one, when talking about quality inverters, their surge and limited run outputs are considerably higher than the rated output. (not counting the made in china truck stop specials here) For example my old little Heart Freedom 10, (1,000 watt inverter) is rated at 3,000 watts for up to 5 minutes. Just looking at one random example online the Xantrex 3,000 watt marine inverter is rated as AC surge up to 75 amps, which should be in the ballpark of a 2HP motors LRA rating and therefore its starting load.

Ike

 

[frogman62]

rlloyd,

I have been building compressors for over 40 years and have several on large boats. I can build the 4.2 CFMm units with a small diesel engine. The 3 phase mentioned by veriqster is a good option. 3 phase 3 hp motors are very good and cheap and electrical mod to for driving would be easily accomplished.
Check my web site < sheldensportinggoods.com> or give me a call at 316-992-0505
and I see what options we could consider
Jim Shelden