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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)

    No, having heard others talk of one it was somethign I kept saying I was going to do. I started it. A propane should be easy enough to get. Have you jsut Tee'd it into the line (very easy to do ) or have you an in and out on the tank, which I would imagine makes it work as a damper better? Harder to do though. But 30 gallons, Jeeezz! 'spose in low pressure gas that is not much.
    Last edited by BritCNGUser; 05-05-2015, 06:24 PM.

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

      I have 90 ft of 1 1/2 inch gas line between my meter and compressor I thought that would be plenty of volume to dampen the pulses, it wasn't. It was literally rattling the meter, put the dampner in and everything calmed down, pump rate increased.

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

        I welded in two pipe fittings, gas goes in side near the bottom and out the top.

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

          Ahhh! Now I have the grand sum of 15 foot of pipe between meter and pump, I may be rattling my utility co.s regulator. No, I will rewrite that, I must be! That would certianly explain why with lower demand stuff like my water-heater and gas tumble-dryer leave the 21Mb pressure with no dip. The regualtor works but does not like my Coltri. Or it may be the meter complaining.
          I have an old propane cylinder knocking about and I was doing thsi job but never really got to it. I am no welder. Seems I have a must-do. Utilty regulaor to be checked later today however I am beginning to think the pulsing is 'doing for it'. I am ever more convinced this is a supply problem becaues it rusn sweet-as-a-nut pulling atmosphere. In fact it runs better thatn I have ever seens it run form new. Never done thsi before, (it never occurred to me) but I ran it pulling air for 20 mins last night and after 10 mins of settling, I saw 4 & 38 bar at 1st and 2nd. Even 70-75 degs C on the 2nd & 3rd stages (1st was lower at 55 degs). 4 & 38 bar - With pressures the like of which I have never seen pulling from my gas-supply.

          Air is denser than methane by 30% so easier to get to presssure but I can't see that completely accounting for what I see.
          Last edited by BritCNGUser; 05-06-2015, 01:54 PM.

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

            Originally posted by BritCNGUser View Post
            Agreed totally proposterous, perhaps I did not explain myself well. The 2nd stg gauge see-saws up and down when I restrict the inlet whether hooked to my gas utility or to atmosphere. That over-pressure can only be coming for as you say the 3rd stage. But when I let it have all the atmospheirce air it wants, all is dandy. No third stage issue or any other come to that. After running to 'pressure up' if I restrict the inlet I see 68-73 degs C at the 3rd stage, 55 at the third, and about 35-40 at the first (all measured on the exhaust port), higher blowby. Let it run unrestricted pulling air by PU I see all roughly even at 55-60 degs C, and lower blowby.

            I definitely have more blowby on my first stage and there is definitely soemthign amiss with my supply. You are likely right about the 3rd stage. But I still don't have a completely rational explantaion for all I see. For cryin' out, it works to atmosphere. Unless i have a combination of issues still dogging me. Having my gas-utilty regulator looked at tomorrow, but even this bugs me, because on light load, my water heater, adn gas dryer runnign together the regulator holds pressure steady only 1Mbar below static, as it should. It only struggles when i throw the Coltri at it.
            I would be stoked to be runnng those low temps.
            My MCH 13 is 106 degrees C on stage 3, and mid 80's on stage one and two running at full speed. If I slow the VFD down to 30hz the third stage drops down to 100 degrees C and the second stage to 78 and the first to 80. I have unrestricted airflow and only a canopy protecting the compressor from the weather.

            I am checking temps on the outlet fitting from each stage with a thermistor that registers degrees celsius on my multimeter.

            Another interesting variable is my stage one pressure is 85 psi running full speed (60hz). When I slow it down to 30hz the stage one pressure increases to 95psi. I am presuming this is a consequence of the compressor being able to suck in a denser charge of gas at a lower rate of consumption. I know I have positive pressure at the compressor inlet as there is a pressure switch on the pulse tank that shuts things down in the absence of pressure.



            Karl

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

              Gents I am FINALLY FINALLY cracking this one. Things now make sense. Karl don't be down-hearted on temps. I get pretty mucha s you do, a tad cooler but not by much. The temps I gave as i say are from cold to PU, ie cold only running to 3-4 mins. [My way of testing my latest changes to eliminate other factors]. Run the thing for 20-25 mins and by waving my whizz-bang infra-red digital thermometer really close to keep the beam area tight, I find oddly that the exhaust ports are not the hottest point I can find [but IR thermometers don't read shiny surfaces well - i intend to spray the exhaust-fittings matt-black]. Right near the joint between cylinder and head is hottest at 88-91 deg C. [on 2nd & 3rd stages] Dead-centre to 2nd stage valve head also sees 88-91 deg C. My 1st is running far colder 65 degs [at the joint] but my guage says 80% of my blowby is coming from the first so it is not pulling as it should. Now I have proper gauges i will be playing with my first stage rings and barrel again this weekend. Did this before but was blindfolded without gauges so got nowhere, 'sides the 1st stage will not seat if input is restricted. I see my 1st stage blowby climb when I restrict in my pulling air tests.

              I am 90% convinced I have a supply regulator rattling issue. I lashed in a tiny propane tank I have last night and it helped. My 1st stg blowby dropped. Now.... I got hold of a old 47kg propane cylinder today (about 4'6" high not unlike flatracker's) and will get two ports welded to it and throw that into the supply line. That should kill all before it.. I also checked the spec of my regulator. It si actaully part of its function to drop-off at 80-90% of its capacity so will never work as required. A theory: The reason my install worked initially was because my 1st stage was spanking new and mashed the regulator, until it gave in. Without guages all I was checking was gross fill time to my tank, (which was very good) but who knows waht was really happening. Not entirely convinced by my own theory but verifying this now.

              I am checking temps on the outlet fitting from each stage with a thermistor that registers degrees celsius on my multimeter.
              I know I have positive pressure at the compressor inlet as there is a pressure switch on the pulse tank that shuts things down in the absence of pressure.

              You made me chuckle - and I thought my geek credentials were in the stratosphere. A thermistor???... now I want one. Jeez, how much kit have you got on that thing??!
              Have you got the tin-foil propeller-hat and camo-trousers to go with? Go on, say you have.

              You can tell us....

              You have, haven't you?

              Odd what happens to your 1st?? I reckon to see 1st pressure liek that when I have the supply sorted. I see no point doing my 1st stage rings & cyl [again] until I do.

              With my small propane bottle in-line pulling NG I get 4 & 42 bar at 1st & 2nd when third is at 195. Much improved. I ahve never seen a gauged-up MCH5 to know but what are you all seeing at the 1st and 2nd stages for pressures. Coltri MCH5 spec is 3.5 & 35 bar respectively [MCH13 5 & 40]. Seems we all see more than that. Here's anothre thing, watching my utilities gas meter spin ( and it do fairly spin) my pump in one minute pulls 111 l/min which is way over the 85 l/min Coltri spec it for. Agreed it does pull down the input pressure to 15 mbar (below the 17mBar spec) but there's not much to bitch about now. I am waiting to get my flowmeter installed on the input too. I almnmost don't beleive my gas-meter. 111 l/min is way over.

              I am winning I tells ya.
              Last edited by BritCNGUser; 05-07-2015, 06:53 AM.

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

                Hi Brit, In regards to the geek credentials I am probably doing well. I am actually looking for a 12 step program that addresses compressor tinkering addiction as I continue to acquire compressors to experiment on and rebuild even though my original fuelmaker runs like a charm.

                The thermistor came with a cheap (but fully featured) chinese multimeter I bought from Harbor Freight. It works really well for monitoring temps. If the 12 step program doesn't materialize soon I am thinking about epoxying a thermistor to each stage and connecting to a data monitoring/recording device (along with pressure transducers for each stage) and a oil pressure and temp transducer). I would like to set up to shut down if anything goes out of normal ranges.

                Good job on getting your pump figured out. I did no welding on my propane tank. Just used the liquid port for the inlet and the vapor port for the outlet. Mine is at least 50 gallons and it works well.

                Karl

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

                  Originally posted by flatracker View Post
                  I welded in two pipe fittings, gas goes in side near the bottom and out the top.
                  Flatracker....could you attach a picture of your pulse tank setup. Thanks

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

                    Originally posted by cngtennessee View Post
                    Flatracker....could you attach a picture of your pulse tank setup. Thanks
                    Currently in new jersey trying to line out a turbo issue for my worst no pay customer " my daughter" will be back in a week.

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

                      Hi Brit, In regards to the geek credentials I am probably doing well. I am actually looking for a 12 step program that addresses compressor tinkering addiction as I continue to acquire compressors to experiment on and rebuild even though my original fuelmaker runs like a charm.

                      The thermistor came with a cheap (but fully featured) chinese multimeter I bought from Harbor Freight. It works really well for monitoring temps. If the 12 step program doesn't materialize soon I am thinking about epoxying a thermistor to each stage and connecting to a data monitoring/recording device (along with pressure transducers for each stage) and a oil pressure and temp transducer). I would like to set up to shut down if anything goes out of normal ranges.
                      You sad, sad man. Tragic is what it is. I ahve a similar issue with my Dowling Sumo and mess with it forever, (don't ask - it's a stove), whereas I have a perfectly functioning gas boiler. Take the tablets, the warder will be along in a minute dear.

                      Good job on getting your pump figured out. I did no welding on my propane tank. Just used the liquid port for the inlet and the vapor port for the outlet. Mine is at least 50 gallons and it works well.
                      UK cylinders only have one port and tap and I had origianlly thought I could bodge a 'T' fitting atop mine. But I have to do it properly.
                      Last edited by BritCNGUser; 05-20-2015, 06:55 PM.

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

                        no carl I dont think so gives me the oil

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

                          So Brit did you or trd ever get your coltris back to spec?

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

                            Yes. And it was never the Coltri in the first instance. A flow gauge on the input along with a Dwyer 5kpa gauge and a long process of elimination finally got me there. I have a deficit in my supply. It turns out my utility for reasons I have yet to get to the bottom of, put the street pressure down from 55mBar to 32mBar. My Coltri has been hunting for gas and that is what stopped the 1st stage seating.

                            Pulling air with everything changed, the thing is sweet as a nut. Pressures-up a beaut. I am now looking to young Karl's trick of slowinghte speed controller down to meet the supply capacity.

                            I'm also onto my utility now.

                            Tell me, is there a trick to weldin- up old propane cylinders safely? I am sure I read somewhere on here of hwo someone did theirs, can't find it.

                            Q1: Will drilling it be an issue?
                            Q2. Once I get the torch out do I have to worry about gas-in-the-metal as I would with say hydrogen? I've seen blokes make BBQs and wood-fired terrace-heaters out of the things so I suspect I'm cry-babying a tad, only I quite like my body parts where they are!


                            I found this, it sounds sensible...

                            http://www.millerwelds.com/resources...-Propane-Tanks
                            Last edited by BritCNGUser; 05-20-2015, 07:05 PM.

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

                              ok it sounds like 55mbar is about 3/4 of a psi and 32 is about 1/2 psi now this sounds like a very low street pressure must have real big mains on the street. my thoughts would be to see what size orfice is in the house regulator and than contact the company that makes the regulator and buy a bigger orfice at these low pressures orfice size matters big time.you may be able to fix this for just a few dollers there should be a breakdown drawing on the companys web site. my thoughts are that this drop in pressure would cut your gas flow by more than 50%.

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

                                Yes, underway I see it pulled down to 11-13mBar (about 0.20 psi) which is way too low. I have a 3/4" pipe coming in but the street mains I'm told are massive. I have checked. We have at most 80mbar (1.16psi) in the street. Usually less. If I had even 55mBar coming to my meter I would be fine. I understand I used to have this.
                                I spoke to my gas fitter. Different to US set-ups by all accounts….Perhaps a lesson in a different mindset. What we have here is about legacy. I know the UK had gas for lighting some 180 years ago. This would be coal-gas. The white-heat of technology meant low pressure big bore pipes. [Used to be vitrious - Made of clay I undestand???] Used for street lighting and lighting for the very rich.

                                Back in hte day, once Mrs Jones and Mr Smith had lighting that took no more than the low pressures of the technolgy, upping the pressures to more desirable levels could take streets out. The suppliers were not ready to change everyone's appliances so the UK got stuck. In domestic supply we see very low pressure gas. We do see 7Bar on inter-town trunk routes but not the trunk-feeds to our homes.
                                Whereas when you got to gassing-up US cities, a higher pressure system for stateside could be put in afresh which of course has to be better.

                                I will do some more digging.
                                Last edited by BritCNGUser; 05-21-2015, 03:03 AM.

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