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look what I found lurking in my 3rd stage head (MCH5)

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  • Re: look what I found lurking in my 3rd stage head (MCH5)

    Typo sorted... thinking about my question the clue is in the name as in VFD. Clearly the VFD sets the speed... fool. I got there in the end.

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    • Re: look what I found lurking in my 3rd stage head (MCH5)

      Originally posted by flatracker View Post
      Ray if you will look in coltri's own operation manual for the mch13 even the unit set at 3200psi is rated "non continuous pressure" at that pressure.
      Thanks for bringing that to my attention. But I have never had much faith in their manuals. I am going by actual experience and we have dive shops that run them at 4500 psi all day long. But 2-3000 is pretty accurate time frame to get an overhaul for air pressures. My best tech guru thinks it should be longer since you are working with a lot lower pressures. Although he has said that he is seeing people use some odd oils that are way too thin.
      Ray Contreras
      CompressorStuff.com

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      • Re: look what I found lurking in my 3rd stage head (MCH5)

        I am no coltri expert but if they would slow these things down to about 900 rpm and put a 50 weight polyglycol compressor oil in them most of these problems would disappear overnight

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        • Re: look what I found lurking in my 3rd stage head (MCH5)

          It all goes back to heat, and the three stage design has to deal with much higher temperatures than a four stage. The second stage of a four stage will take the gas from 60 to approx 325 and have a discharge temp of about 250 Fahrenheit, a three stage will take it from 70 to 550 and have a discharge temp over 400. Any thing you can do to remove this heat will lengthen the life.

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          • Re: look what I found lurking in my 3rd stage head (MCH5)

            I can vouch that Coltri's manuals are at the very least iffy. Full of contradictory information from part numbers to service intervals. eg: My user manual has oil change intervals at 250 hours in the front and 500 hours in the back etc etc. I ignore both and aim for 150 hours and use Anderol 755. Coltri's own Coltri CE750 is Aluchem Alusynt CE 750 but I think you'll struggle to find Alusynt CE 750.
            Last edited by BritCNGUser; 04-03-2015, 05:37 AM.

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            • Re: look what I found lurking in my 3rd stage head (MCH5)

              Brit you would be better served with a polyglycol lube such as summit pgs 100 or 150, those lubes you named are all diesters, are fine for air but are,t really suitable for Nat gas, diesters tend to thin out with high pressure gas exposure and polyglycols do not.

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              • Re: look what I found lurking in my 3rd stage head (MCH5)

                Originally posted by flatracker View Post
                Brit you would be better served with a polyglycol lube such as summit pgs 100 or 150, those lubes you named are all diesters, are fine for air but are,t really suitable for Nat gas, diesters tend to thin out with high pressure gas exposure and polyglycols do not.
                This is above my pay-grade, I think this requires a saparate thread. This onemeanders too much already. I will start one...

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                • Re: look what I found lurking in my 3rd stage head (MCH5)

                  20150403_154736.jpg

                  After a quick trip to my local harbor freight I got a arbor press, bearing and seal driver set and a bearing separator I was able to get the race's out (using the 44.5mm driver)

                  more updates to come....been taking it easy this week but going full bore next week

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                  • Re: look what I found lurking in my 3rd stage head (MCH5)

                    Brit it does wonder a bit , but like sausage taste great, just don't watch the process. If you wanted slow and uneventful you would own a fuelmaker.

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                    • Re: look what I found lurking in my 3rd stage head (MCH5)

                      Right now I would quite like an FM! Only when it is working to spec it still won't come near mine even playing-up.

                      I was really hoping this would offer up a solution...
                      Just done a input pressure test with a mates manometer. Out of a UK gas meter with all appliances off, I get the correct regulated static pressure of 23 millibar (about 0.3psi) which is right at the bottom of what a Coltri is specced to run at. That is but a babe-in-arms -breathing for a pressure figure. It expalins why when I input to atmosphere I saw no reduction in pressure at the first stage gauge. I note a MCH5 can run at input pressures of 200 mbar (3.0psi) thus tens times what I actaully have and Joe runs at near that. This can't be helping because it takes any supercharging effect away form me.
                      I am struggling witha dynamic pressure becaue the manometer is a digital whizzbang and the dispaly jsut goes ape running dynamic pressure and there is no easy way to snub the thing. I march on...

                      PS: Just found a way to do a dynamic test. Rather than at the pump end of the gas supply I took the test point off at the meter. It seems the extra lenght of pipe acted as a damper for the dig. manometer, and I got with no other appliances running pressure of 19millibar, now a Coltri is said to need 17millibar to run so it is tight.
                      Attached Files
                      Last edited by BritCNGUser; 04-04-2015, 02:17 PM.

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                      • Re: look what I found lurking in my 3rd stage head (MCH5)

                        Originally posted by BritCNGUser View Post
                        Right now I would quite like an FM! Only when it is working to spec it still won't come near mine even playing-up.

                        I was really hoping this would offer up a solution...
                        Just done a input pressure test with a mates manometer. Out of a UK gas meter with all appliances off, I get the correct regulated static pressure of 23 millibar (about 0.3psi) which is right at the bottom of what a Coltri is specced to run at. That is but a babe-in-arms -breathing for a pressure figure. It expalins why when I input to atmosphere I saw no reduction in pressure at the first stage gauge. I note a MCH5 can run at input pressures of 200 mbar (3.0psi) thus tens times what I actaully have and Joe runs at near that. This can't be helping because it takes any supercharging effect away form me.
                        I am struggling witha dynamic pressure becaue the manometer is a digital whizzbang and the dipslay jsut goes ape running dynamic pressure and there is no easy way to snub this dig. manometer. I march on...
                        I might be wrong , but doesn't coltri recommend from 2 psi to 3 psi for gas input ?

                        Edit: I now see 17-200 mbar , not sure where I read 2-3 psi for best performance.
                        Last edited by Lakewood90712; 04-04-2015, 02:00 PM.

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                        • Re: look what I found lurking in my 3rd stage head (MCH5)

                          I might be wrong , but doesn't coltri recommend from 2 psi to 3 psi for gas input ?
                          I am sure higher is better... See my PS and edit, it crossed with yours and thus got added after your post. Sorry. This forum has scaled my pic it might not be readable but it says Range is 17millibar>>200millibar.

                          23 static and 19 dynamic, my gas supply is working to UK spec. So supply is not the nice simple answer. Frankly I was hoping it was my supply regualtor or meter but no. Odd thing though. When the pump tops-out at 200 bar and clicks off, I get 120millibar (1.7psi) for a bit at the meter but I assume the crankcase must be blowing-down and venting to the supply. I assume this is correct, the blow-by pressure has to go somewhere. I am surprised it is not higher
                          Last edited by BritCNGUser; 04-04-2015, 03:38 PM. Reason: Typos abound...

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                          • Re: look what I found lurking in my 3rd stage head (MCH5)

                            I have just put my tachometer (calibrated via my workshop Fluorescent light fitting) to the flywheel. Used a bit of hi-reflective tape on one of the fan-blades/spokes for the tach to pick up on. I see 1200 dead from zero to 200 bars and all in between. So it is slow by Coltri spec (1240rpm) to 40rpm which I can't see as here nor there. Again another simple issue I was hoping to find the issue hidden within.
                            Last edited by BritCNGUser; 04-05-2015, 10:23 AM.

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                            • Re: look what I found lurking in my 3rd stage head (MCH5)

                              Originally posted by BritCNGUser View Post
                              Right now I would quite like an FM! Only when it is working to spec it still won't come near mine even playing-up.

                              I was really hoping this would offer up a solution...
                              Just done a input pressure test with a mates manometer. Out of a UK gas meter with all appliances off, I get the correct regulated static pressure of 23 millibar (about 0.3psi) which is right at the bottom of what a Coltri is specced to run at. That is but a babe-in-arms -breathing for a pressure figure. It expalins why when I input to atmosphere I saw no reduction in pressure at the first stage gauge. I note a MCH5 can run at input pressures of 200 mbar (3.0psi) thus tens times what I actaully have and Joe runs at near that. This can't be helping because it takes any supercharging effect away form me.
                              I am struggling witha dynamic pressure becaue the manometer is a digital whizzbang and the dispaly jsut goes ape running dynamic pressure and there is no easy way to snub the thing. I march on...

                              PS: Just found a way to do a dynamic test. Rather than at the pump end of the gas supply I took the test point off at the meter. It seems the extra lenght of pipe acted as a damper for the dig. manometer, and I got with no other appliances running pressure of 19millibar, now a Coltri is said to need 17millibar to run so it is tight.
                              You are getting .3 psi plus 14.7 equals 15psi, 3 psi measured would be 17.7 absolute only about 17 percent difference no where near enough to cause your flow problems

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                              • Re: look what I found lurking in my 3rd stage head (MCH5)

                                Thank you flatracker, that confirms what I thought. 0.3 or 3.0psi it makes no real odds. Input pressure is not the problem here. I plug on.

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