Coltri MCH 11, Electric or Gas driven?

[Aris Penaranda]

Hi all.
After doing some research, I have narrowed down my choice to a coltri MCH-11. Gas needs will be about 6 tanks of AL-80 per day, 4 times a week. However I have not yet finalized which is better between a gas powered or electric driven compressor. The power available is 220v single phase at a cost of 0.25 US Dollar/ KWH. Gas prices are about 1 US dollar per liter. The compressor will be on a garage. No intention of moving it around. Sound is not an issue. I assume the electric driven model will cost less to operate. But the voltage sags below 200 volts at night. Another concern is the typhoon season which sometimes knocks the power from the grid for a week. I don't have a generator. So my initial idea is to get an electric driven MCH-11, and purchase a small gas engine to drive the compressor or a small generator whichever is required. What is the recommended engine size that will fit on the frame of the MCH-11 that will provide close to the capacity of an electric driven model? Any input will be very helpful.

 

[RayfromTX]

That's a real scuba diver. The power is out for a week and you have no generator but if you can fill your scuba tanks, all is well. I love it.

I think a generator to drive the electric motor that can also supply power to the other domestic needs when the power is out would be a plus. It would also be good to use it when the voltage drop becomes excessive. 10% voltage drop is terrible for motors.

 

[Aris Penaranda]

Its not a big issue for us not to have grid power all the time. But having to drive to the nearest dive shop 130 km away to get 6 tanks filled is costly and inconvenient. That was the main reason that made me think to fill my own tanks. The compressor cost will already make a big dent on the budget so I'm trying to cut corners where possible. However, having a bigger generator is a good idea and may not cost much if I put it together myself. Thanks for the tip.

 

[BoltSnap]

From experience, gas powered compressor needs more ventilation and making sure that you have a wide long hose connected to the intake pipe (several meters long) to ensure that the air pumped into the compressor is not contaminated by the exhaust fumes from the compressor (it has to be hung very high above the compressor in the open air upwind from the compressor exhaust.

 

[Billy Northrup]

I'm not sure what the common voltages are in your country, however some motors can be tapped at different voltages. Example domestic power in the US is about 240volts, industrial voltage is 208 but often closer to 200.. If you can tap the motor at 208 you should be fine and or a slightly smaller pulley and all will be good. Gas is cool for expedition diving but filling that many tanks a week, listening to the engine run would get old quickly. Enjoy!

 

[BoltSnap]

Example domestic power in the US is about 240volts

Since when did the US switch to 240V from 110V?

 

[RayfromTX]

One leg of single phase gives 120v two legs gives 240v. We use both.

 

[BoltSnap]

One leg of single phase gives 120v two legs gives 240v. We use both.

One needs to specify how many power phases when making this type of statements, compressors AFAIK are made specifically to the type of power you are going to be using including how many phases, single vs. 3P.

 

[Billy Northrup]

One needs to specify how many power phases when making this type of statements, compressors AFAIK are made specifically to the type of power you are going to be using including how many phases, single vs. 3P.

We don't have domestic 3phase in the US, it would be a rare exception like a farm. 120/240 in the US is called split phase. Each hot leg is 120 to neutral and 240 to eachother. All plugs/lighting in houses are 120v, 240v is primarily for Air conditioning, Dryers and stoves.

 

[BoltSnap]

We don't have domestic 3phase in the US, it would be a rare exception like a farm. 120/240 in the US is called split phase. Each hot leg is 120 to neutral and 240 to eachother. All plugs/lighting in houses are 120v, 240v is primarily for Air conditioning, Dryers and stoves.

So air compressors will be rated for either 110V or 240V in the US?