converting electric clarke compressor to petrol engine

[jeff.]

Hi all ,

have a 150ltr clarke air industrial compressor , the motor has burned out , can get a new motor for £140 , but i don't have a good electric supply and the 3hp motor struggles to start when compressor is cold and sometimes has to be emptied to start again ,

so have a spare 5.5 hp honda clone engine gx160, and looking at fitting that ,

does any one know how to work out what size pulley I will need for for the engine to get ,

I can fit the pulley of the original motor , but i think this will make it run at to high rpm ?, electric motor is 2800rpm , and pulley is 6"

not sure what revs a gx 160 runs at but guess its more the motor

so have a a smaller 2.5" pulley to try as well as most petrol compressor ive seen have a small pulley on the engine ,

any one have any ideas?

thanks

 

[p0689109]

Surely the fact that the motor burnt out is indicative of the fact that you were having trouble starting it! Unless the pump itself is very tight I would not think a 3hp motor would strugle to turn it. Unless of course your supply cable is not up to the starting demand i.e does it need a 16 amp supply?
As for the pulley sizes have you has a scan through the compressor section of the forum as I am sure that has been covered on how to work out pulley sizes.
Good luck either way.
Michael T

 

[jonjoe]

also does the engine run the same direction of the pump??

what to do when the compressor reaches max pressure??

 

[jonjoe]

was the dump valve working you should of heard it hissing

 

[the snooper]

to use the engine you will need a valve that will blow off when the tank is full otherwise it will just keep filling

 

[jeff.]

I have 16 amp supply with the blue plugs, and pump is not tight ,dump valve, un loader all worked ,

engine runs correct direction and just going to have a pressure relieve valve when is reaches max pressure ,

( i don't use this compressor very much , i have another electric 14cfm compressor aswell)

 

[eil]

If you intend to change it to a engine running compressor you would need a few extra bits such as a genie, heres a few pics off my engine driven small Clarke

 

[jeff.]

If you intend to change it to a engine running compressor you would need a few extra bits such as a genie, heres a few pics off my engine driven small Clarke

do you have any more pics of the pulleys/pump and pully size ,cheers

thanks for reply's

 

[eil]

do you have any more pics of the pulleys/pump and pully size ,cheers

thanks for reply's

Now would you believe it I have just this morning replaced the drive belt on mine and put the guard back on, a job I don't particularly like doing , But I will take it off tomorrow and measure it just for you.

 

[armalites]

I have a petrol powered compressor that wasn't working correctly when I first got it.

It has a pressure valve that throttles back the back engine once it's up to pressure.

Problem is the motor will still keep pumping.

I fitted a centrifugal belt drive clutch to the engine so when the the engine is at idle the pump doesn't run.

All works a treat.

 

[gerrymoore]

I've got a crystal air 2000 ...think its a twin cylinder compressor driven by Honda 5.5hp..just measured the pulleys best i could through the guard...motor pulley is 4" and comp pulley is 12" so roughly 3:1 reduction. While I'm here..the motor seems to make a lot of noise and I wonder if anyone has heard of a way to quieten it..I did try with a car silencer but that didn't seem to help much..can I get an exhaust (cheap copy??) from a genny?? Also very interested in Armalites post...I have to keep an eye on mine and stop the motor when it reaches 100psi...no cut out or idle valve is fitted...can you give some more details on where and how they're fitted and where you got them. I only use my compressor for plasma but just finished my cnc machine so will be using it a lot more hopefully.

 

[jeff.]

I've got a crystal air 2000 ...think its a twin cylinder compressor driven by Honda 5.5hp..just measured the pulleys best i could through the guard...motor pulley is 4" and comp pulley is 12" so roughly 3:1 reduction. While I'm here..the motor seems to make a lot of noise and I wonder if anyone has heard of a way to quieten it..I did try with a car silencer but that didn't seem to help much..can I get an exhaust (cheap copy??) from a genny?? Also very interested in Armalites post...I have to keep an eye on mine and stop the motor when it reaches 100psi...no cut out or idle valve is fitted...can you give some more details on where and how they're fitted and where you got them. I only use my compressor for plasma but just finished my cnc machine so will be using it a lot more hopefully.

thanks for the reply , maybe I will try a 4" pulley now ,

not sure how to get the engine to cut out , I think you need some kind of unloader valve connected to the Governor/throttle ,

i am just using the standard exhaust like below , but compressor will be outside of the workshop ,


http://www.ebay.co.uk/itm/EXHAUST-M...wnmower_Parts_Accessories&hash=item53ef34b576


thanks

 

[brightspark]

if u use a petrol engine u will need a compressed air to atmosphere unloader . machine mart sell them but there over 68 quid

 

[the snooper]

to get the engine to cut out simply use the original pressure switch and have it cut out the ignition circuit, but that means you will have to keep an eye on the pressure and manually start the engine each time the pressure drops, if you engine has electric start ,by adding another pressure switch and have one set higher for cutout and the other set lower with a simple start timer you could make it fully automatic

 

[gerrymoore]

Thanks for the help all...I'll look into trying some of the suggestions:-))

 

[KemppiFrog]

Some older Peugeots had electric clutches for the cooling fan and car aircon systems do too. Might be a way here, esp as they allready have pulleys fitted and can be controlled by the existing switch. The engine will be governed, so will not overspeed off load.
KF

 

[normspanners]

A lot of normal electrical pressure switches have a mechanical pressure unloader built in, if it was plumbed in the pipe from to the compressor head to receiver before the check valve it will unload the compressor. I would pipe it in large copper pipe to act as a heat sink to get rid of hot air off the head. they are usually 6mm bore so that would easily cope with the flow of a 15 20 cfm comp.

 

[brightspark]

A lot of normal electrical pressure switches have a mechanical pressure unloader built in, if it was plumbed in the pipe from to the compressor head to receiver before the check valve it will unload the compressor. I would pipe it in large copper pipe to act as a heat sink to get rid of hot air off the head. they are usually 6mm bore so that would easily cope with the flow of a 15 20 cfm comp.

the unloader on the electrical pressure switches are only rated to pass a small amount of air whats in the pipe between pump and tank . if u were running the full pressure from the comp through it would heat up rapidly and ruin it the only other alterative to the proper unloader is use the pressure switch to operate a solenoid to fresh air between the pump and one way valve to tank

 

[normspanners]

the unloader on the electrical pressure switches are only rated to pass a small amount of air whats in the pipe between pump and tank . if u were running the full pressure from the comp through it would heat up rapidly and ruin it

thats why I said to run it through large dia copper pipe to act as a heat sink I have seen them when the contacts have stuck and the compressor has just kept going and they have just worked as normal after, when the contacts have been sorted, because the compressor isnt compressing to a high pressure so it dosnt produce as much heat. But I have used a solenoid valve for the same purpose before now with them on a switch, for normal use so that the compressor could be used on a small genny or mains.

 

[jeff.]

have got the engine running the compressor now , runs well , but think i need a bigger pulley for the engine , as found this site that you can work out rpm/pulley speed ,

(not finished yet in the pic , still have to pressure relief valves etc..)

with the electric motor it had 6" pulley on motor and 12" on the pump, (2800rpm motor so pump speed 1400rpm)

so going to try a 5" pulley on the engine ,

thanks
http://www.culvermotor.com/Engineering-Formulas/Pulley-and-RPM-Calculator.html