Coltri MCH-6/Max Air 35 Motor

[jkaterenchuk]

Thanks for your help Ray.

John

 

[ghettoman]

Be aware...at 2.2Kw (the single phase version on coltri) the compressor output will be around 80L/min
If you want 100L/min you should use a 3Kw single phase electric motor, like they use for 100L/min 3Phase version.

 

[oxyhacker]

The NEMA 56-framed "specials" have become more or less the standard in the industry when you are looking for a lower-priced 2-5 HP motor and, being relatively small, tend to fit most applications that call for a similarly powered motor. Don't think the Coltri is drilled for them, but easy enough to drill a few more holes.
I put Surplus Center 56-frame 3HPs on an MCH6 and a Bauer with no problems, but they don't list that exact model anymore.

 

[gav6280]

Be aware...at 2.2Kw (the single phase version on coltri) the compressor output will be around 80L/min
If you want 100L/min you should use a 3Kw single phase electric motor, like they use for 100L/min 3Phase version.

So what happens if you put an 5hp 3.7kw motor on?
(Apart from having to hard wire it in as it will draw 16 Amps).

And how will its rpm alter the performance?

 

[rcontrera]

The biggest reason that the single phase motors are set up with a pulley to run a little slower than the three phase and the gasoline driven compressors is amperage. The single phase motors draw 29 amps for the 110 and 14 amps for the 220. The electrical guru in the shop said that both motors come from Italy with a start/stop switch that, in the case of the 110 would burn out at higher amperage and in the case of the 220 (which actually has a small motor starter built in) would not allow adding of an auto shutdown circuit.

If you are using your own motor and starter, then you can put as big of a motor as you wish! It isn't the horsepower that determines the compressor capacity ... it's the motor speed. Just put the proper pulley to end up driving the compressor at no faster than 2800 rpm (the speed for 100 L/min).

 

[gav6280]

So once your compressor is pumping at its maximum capacity over running it with a higher speed motor is just going to do damage then?

Which of the compressors has the largest CFM that i can use on UK spec 240V 50HZ single phase electric if its hard wired to the distribution board on a dedicated cable, so upto 30 Amps.

 

[rcontrera]

We get the two capacities out of the MCH6 by spinning it at different speeds ... 2400 for the 80L/min and 2800 for the 100 L/min. That's pretty fast anyway and spinning them faster is just asking for trouble.

As for how big we can go with single phase, that really depends on the artistry of your electrician. The stock Coltri compressors go as big as 14 CFM on single phase. However, that machine actually has twin 7 cfm compressors stacked in one cabinet and each draws 25 amps. Even our 9CFM MCH16 in single phase draws 34 amps. If 30 amps is your max, then we are looking at the MCH13 at 7.6CFM which is really an excellent size for a single diver, small club or small store.

 

[ghettoman]

......
If you are using your own motor and starter, then you can put as big of a motor as you wish! It isn't the horsepower that determines the compressor capacity ... it's the motor speed. Just put the proper pulley to end up driving the compressor at no faster than 2800 rpm (the speed for 100 L/min).

The horse power is important too.You can hook up a 2,2Kw motor to a bauer mariner and drive it at 1200-1300 rpm.I bet that you will not obtain 200l/m from that configuration.As the presure builds up the motor will be slowed down because it can`t mentain his speed, the compressor will take more power - as the presure builds up- that the motor could deliver.
The ratio was as I remember around 1,5-1,8 cfm /kW to new compressor block designs.

 

[jkaterenchuk]

The NEMA 56-framed "specials" have become more or less the standard in the industry when you are looking for a lower-priced 2-5 HP motor and, being relatively small, tend to fit most applications that call for a similarly powered motor. Don't think the Coltri is drilled for them, but easy enough to drill a few more holes.
I put Surplus Center 56-frame 3HPs on an MCH6 and a Bauer with no problems, but they don't list that exact model anymore.

I can confirm that the frame is not drilled to fit the 56 frame motors. We purchased and installed a 5HP from Tractor Supply and had to drill a few mounting holes. Works fine but we think something is wrong with this particular motor as it seems to draw 17 amps when running the compressor at 2800 rpm. It only rated to 1 amps with a 1.0 SF. So I am going to exchange it for another or a higher amp/SF 5 HP motor.

John

 

[TechDeep]

We get the two capacities out of the MCH6 by spinning it at different speeds ... 2400 for the 80L/min and 2800 for the 100 L/min. That's pretty fast anyway and spinning them faster is just asking for trouble.

As for how big we can go with single phase, that really depends on the artistry of your electrician. The stock Coltri compressors go as big as 14 CFM on single phase. However, that machine actually has twin 7 cfm compressors stacked in one cabinet and each draws 25 amps. Even our 9CFM MCH16 in single phase draws 34 amps. If 30 amps is your max, then we are looking at the MCH13 at 7.6CFM which is really an excellent size for a single diver, small club or small store.

I just realised that digital rpm meter on my gas powered M6ch is running off of the spark plug wire on the gas motor. So, with a (rough measurements) 3.5" pulley on the motor, and a 4.5" pulley on the compressor, I've actually been running the compressor at around 2200 RPM. Since I have read the manual and it doesn't mention this, I assume I am missing somthing?

Also, given my pulley configuration, it looks to me like if I were to go to and electric motor at 3450 rpm, that should put me pretty close to 2800 at the compressor. Again I think I must be missing something, because all of the information I have read about converting from gas to electric have indicated that you must change the pulley size.

Open for suggestions on what I might be missing here. That's usually the wife's job, but she's not real good with pulleys and rpm.