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Gas To Electric Compressor Conversion


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#1 Ryan313 ONLINE  

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Posted April 21, 2013 - 06:24 PM

I have three large compressors, one if in the service truck my Dad used for his tire service business, one is on my trailer, and the other is mostly for parts, and just sits there. I would love to convert it over to electric so I can have it in my garage, and not have to worry about noise and exhaust fumes.

 

How hard is this to do? How large of a motor would I need, the original engine is a Kohler Command 11? Is there a way to have the motor shut off when it reaches pressure? Anything I am missing?



#2 olcowhand ONLINE  

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Posted April 21, 2013 - 06:59 PM

Likely a 5hp (true 5hp, not the ones that say "max developed HP") electric motor will handle it, depending on pulleys used.  Easy to source a pressure control switch.  



#3 Username OFFLINE  

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Posted April 21, 2013 - 08:33 PM

You will need a magnetic starter with a 5 hp motor.! just converted a gas to electric.I used a pressure switch with an unloader connected to a magnetic starter.



#4 marlboro180 OFFLINE  

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Posted April 21, 2013 - 09:55 PM

Ryan- one question a lot of guys are gonna ask ( including myself) is just how big a compressor pump are ya looking to turn? The original gas motor means little, but it sounds as though the pump you want to turn is decent sized enough .

 

A pressure cut- off switch , set to a decent amount below the tank rating at max PSI is a good start to have on hand.

 

A good solid tank, is a must. Mike will attest to that.

 

A gas engine woulda been turning 3600 RPM, and the electric will  be turning something else depending on the voltage, phase and frame .  so you'll have to be considering pulley sizes as well.

 

I know I am missing more than a few things, but one last bit- make sure you put in a high pressure blow off relief valve. :thumbs:



#5 Amigatec OFFLINE  

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Posted April 22, 2013 - 01:12 AM

Most electric motors spin at 3450 rpm, to go from gas to electric divide the HP in half, I.e. 12 HP gas = 6 HP electric.

Also the compressor will have a centrifugal unloader valve on it. On the end of the crankshaft on the compressor there should be an a steel line running up to head. Inside the head will be unloaders valves. Since the compressor doesn't shut completely off, but idles down instead, the pressure control will bring the motor back to idle, and open the valves in the head so it won't pump air, and when it idles down, the centrifugal unloader will exhaust the head pressure.

#6 Ryan313 ONLINE  

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Posted April 22, 2013 - 05:56 AM

Most electric motors spin at 3450 rpm, to go from gas to electric divide the HP in half, I.e. 12 HP gas = 6 HP electric.

Also the compressor will have a centrifugal unloader valve on it. On the end of the crankshaft on the compressor there should be an a steel line running up to head. Inside the head will be unloaders valves. Since the compressor doesn't shut completely off, but idles down instead, the pressure control will bring the motor back to idle, and open the valves in the head so it won't pump air, and when it idles down, the centrifugal unloader will exhaust the head pressure.



So will I need the pressure control switch? I would think that I could leave it on and once it gets to pressure the valves in the pump will open like it would if it had a gas engine on it.

#7 Amigatec OFFLINE  

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Posted April 22, 2013 - 06:02 AM

So will I need the pressure control switch? I would think that I could leave it on and once it gets to pressure the valves in the pump will open like it would if it had a gas engine on it.


I would think it should, normally the unloader is on the electric pressure switch. After the compressor stops spinning it should bleed off the head pressure.

Can up upload some pictures?

#8 Ryan313 ONLINE  

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Posted April 22, 2013 - 07:14 AM

I would think it should, normally the unloader is on the electric pressure switch. After the compressor stops spinning it should bleed off the head pressure.

Can up upload some pictures?


Of course you can!

#9 ol' stonebreaker OFFLINE  

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Posted April 22, 2013 - 07:28 AM

  How old is the tank and how long has it sat,possibly w/ water in it? There should be a metal tag welded on it stating working and test pressures. If in doubt about it's condition, walk away from it. It isn't worth the risk.

  It would be nice to know the dia of the gas engine pulley on it so you can figure the speed ratio between the engine and pump pulleys to find the optimum speed of the pump. Maybe by finding the pump mfgr and model # this can found on the net. I may be wrong, but I believe a 1750 RPM elect motor will have higher starting torque than a 3450 RPM motor but will require a larger diameter pulley to run the pump at correct RPM. The motor should be 240v and comp duty rated.

  The unloader valve for a gas powered comp also idles the engine down, so I'm not sure how well it will work w/ an elec motor. If you go w/ the unloader only make sure it can work properly w/ an elec motor.

                                               Mike






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