Coltri MCH-6 Stage Temperatures

[zider]

Quick question for the Coltri MCH-6 users in the group. What temperatures are typical for the 4 heads on this compressor? When warmed up to speed for about 5 minutes, I am seeing the approximate temperatures listed below for the stages:

• 1st = 150F
• 2nd = 210F
• 3rd = 240F
• 4th = 170F

Are these values typical? I'm still new to running this compressor and just want to make sure everything seems to be running as expected. If it helps, I'm using an electric motor and the compressor is running right at 2800 RPM (gauge tested). Thanks in advance for the help!!

 

[Tony Pr]

Late reply I know.

• 1st = 60C = 140F
• 2nd = 90C = 194F
• 3rd = 93C = 199F
• 4th = 76C = 168F

After it was warmed up. My 4th stage needs replacement (takes 35 mins to fill a normal tank) so it is not pumping as fast as it should be. I received the replacement 4th stage in the post yesterday, but will wait for an oil change to install it.

Interesting that the worn 4th stage does not change the temperature of the 4th stage.

I have the same setup in terms of electric motor.

 

[zider]

Late reply I know.

• 1st = 60C = 140F
• 2nd = 90C = 194F
• 3rd = 93C = 199F
• 4th = 76C = 168F

After it was warmed up. My 4th stage needs replacement (takes 35 mins to fill a normal tank) so it is not pumping as fast as it should be. I received the replacement 4th stage in the post yesterday, but will wait for an oil change to install it.

Interesting that the worn 4th stage does not change the temperature of the 4th stage.

I have the same setup in terms of electric motor.

Thanks for the reply. Good luck with installation of the 4th stage. The videos coltri has in their website should make it a straightforward job.

 

[iain/hsm]

Would be interested at what point these readings were taken and by what method.
The difference between the actual gas temperature off the discharge valve before any cooling effect with a internal RTD probe and that of the much cooler temperature taken off the external cooling mass of the metal head or tube fitting on the discharge side of the valves is pretty big.

Also if using a hand held infra red temperature gun the difference in measured temperature between that taken on a silver painted or bare metal surface and again the same spot after being spot sprayed with matt black paint.

These are great posts in fact, one of the best informative posts I have seen on here in a long time. Thank you both.

 

[Tony Pr]

@iain/hsm hope this answers your questions.

Would be interested at what point these readings were taken and by what method

Taken using an hand held infra red temperature gun, holding it as close to each of the stages as possible. Externally obviously. I took the maximum temperature off approximately 10 readings (they were all pretty close).

In terms of point, I assume you mean where the measurements were taken? On the side of the cylinder housing, close to where I would call the top of the piston stroke. This is where there are heat sinks on all of the stages, so I assumed this is where it would get the hottest. The compressor had been running for 15 minutes at least and was pumping over 150 bar that whole time (I have a PMV on it at set at 150). I assume that is the hottest it will get.

My compressor is pretty old, so there is not much paint left on it. Just light surface rust.

I mainly did this because I bought an infrared thermometer on impulse and had been busting to come up with a legitimate reason to own it. But now I use it a lot, especially cooking (temperature of deep frying oil, temperature of sugar to make toffee) and to work out what the optimal temp for a cup of tea is.

Happy to take more measurements at more specific spots if you like.

I am always amazed at the temperature difference of the different ends of the pipes connecting the stages. A lot of heat gets transferred out in the air travelling a meter or so.

I still find it interesting that the worn 4th stage does not change the temperature of the 4th stage. I thought it would be cooler with the air leaking into the sump.