Coltri MCH-6

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I have MCH-6 two years now. Had some problems with gun so have not used it much. Less than 10 hours. Electric 220v version. I had the gauge leak all its fluid out for some reason. I called coltri, they said this happens all the time. The rubber plug fails and leaks the oil, the gauge still works perfect without any oil. They said I have to buy the new gauge at $65.00 because I was 2 months out of warranty. Kinda surprised about that, because the girl told me it happens all the time. Disappointing for sure. I will only buy a new gauge if I ever sell the unit, it works fine. Love mine the times I have used it.
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My gauge failed as well. At first I thought the plug just fell out and spilled all the gauge's fluid everywhere. But after filling the gauge with the correct mineral oil I discover my gauge must have an internal leak that allows pressure to build up inside the gauge which blows the plug out. I just put a metal plug in the port where the gauge installs and use another gauge that's plumbed into the system. Other than that the unit has worked perfectly in the 4-5 years I've owned it. And in that time I've only put a few hours on the unit because of how fast it tops off my air tank.
 
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It is interesting to know about the pressure gauge losing it’s glycerine. I will keep an eye on that, on mine.

azccj- “But after filling the gauge with the correct mineral oil I discover my gauge must have an internal leak that allows pressure to build up inside the gauge which blows the plug out. I just put a metal plug in the port where the gauge installs and use another gauge that's plumbed into the system. Other than that the unit has worked perfectly in the 4-5 years I've owned it.” 

Did you use mineral oil, or glycerine in the gauge?


 
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Jerkey said:
I accidently started my Coltri MCH-6 220V with the bleeders closed the other day. As soon as I realized my mistake I panicked and opened the bleeders to let some pressure off then closed them back up and continued filling my Great White tank. The compressor worked fine with no issues. Should I be concerned about anything??

Thanks,

Mike
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Not at all. Opening the drains before starting is simply an effort to keep the psg off the pistons till they have a chance to warm up. Kind of like starting your car and letting it warm up before driving off. Good idea to do, but not a deal killer. Just try to remember next time. 😉
 
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The correct startup/run procedure is this (dictated by Coltri):
1) connect bottle and keep valve closed.
2) start compressor with at least 1 bleed valve open and let it run for 30 seconds.
3) close bleed valve and let pressure build until over pressure valve activates.
4) open valve on bottle.
5) bleed the valve at the bottom of the water extractor every 5-7min for 10sec.
 
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FunGun said:
Not at all. Opening the drains before starting is simply an effort to keep the psg off the pistons till they have a chance to warm up. Kind of like starting your car and letting it warm up before driving off. Good idea to do, but not a deal killer. Just try to remember next time. 😉
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@FunGun What’s “psg” mean?
 
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There is a "psig" lbs/square inch gage and then there is "psia" lbs/square inch absolute.

PSIA - PSI Absolute​

Absolute pressure is measured relative to a full vacuum. The pressure of a vessel completely void of any air molecules would be 0 PSIA, while average atmospheric surface pressure (at sea level) is roughly 14.7 PSIA. Barometric pressure is measured on weather stations and data buoys using absolute pressure sensors; the data gathered by these sensors helps meteorologists track and predict severe weather like hurricanes and typhoons.

PSIG -PSI Gauge​

Gauge pressure is measured relative to ambient atmospheric pressure. A vessel completely void of any air molecules (at sea level) would be roughly -14.7 PSIG, and ambient air pressure is always measured as 0 PSIG, regardless of whatever current barometric pressure is. For this reason, barometric pressure sensors are absolute; if a gauge sensor was used to measure barometric pressure, that sensor would be useless!
 
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on my coltri mch-6 , I had to realign the pulleys, IIRC
I had to move the motor pulley out about 1/8 to 3/16 inch

engineers use PSIA when designing pressure vessels, but us common folk PSI, I personally 'sometimes' use PSIG out of habit from working in the old power plant, but usually it is PSI
www.setra.com

What's the Difference Between PSI, PSIA, & PSIG?

Pounds per square inch (PSI) is a common unit for measuring pressure, but what does PSI Absolute and PSI Gauge mean?
www.setra.com www.setra.com
 
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