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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)

    Originally posted by BritCNGUser View Post
    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
    i just screw the top valve out run an air hose to bottom turn it on and start cutting, 50cfm of air going thru there makes explosion pretty much impossible

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

      Originally posted by BritCNGUser View Post
      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.
      do you have a regulator at the house?

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

        do you have a regulator at the house?
        Yes, sits at 21mBar, see previous pic of the thing. Regulator is not the issue, (I ahd hoped it would be) we tested it, and it was that test that revealed the regulator doing its job, but starvation of gas meant it could not maintain the 21mBar. My previosu tests witha digital manometer had not shown what was truly happening because those things can't indicate like any plain 'old skool' gauge.

        Flatracker wrote:
        i just screw the top valve out run an air hose to bottom turn it on and start cutting, 50cfm of air going thru there makes explosion pretty much impossible
        I have now got a pro on it. But are you sure about your method, the pro I spoke to fills with water to deprive the propane of oxygen. He has argon handy too and will fire some into the cylinder if need be. He said in the past he has done it barnyard-mechanic 'stylee' (as that thread also suggests) tubing a lawnmower or car exhaust into tehm. Carbon Monoxide will purge the oxygen,so gas present or not it simply can't burn. Adding more air will purge it well, but not limit the metal-trapped gases. He said leaving the cylinder water filled will have the propane absorbed by water. [this I am suspect of]

        Anyway the Coltri is vindicated. Deprivations of gas knocked down the pressures in cahin-raction, causing heat and thus dropping initailly the 2nd stage and then the 3rd. It is why I was chasing my tail all this time. Only proper flow & pressure gauges on input showed what was really happening. I am about to put a 30 gall ex-propane cylinder on the input for several reasons, one not least giving the blow-by gas somewhere to go at PU click-off. I see one [big] spike at PU click-off. The ex-propane cylinder can't solve my starvation issues btu I can't wait to see how my pump runs for a minute or two at start-up with the big tank in the line.

        I have permanently plumbed in flowgauges now. Teh oen coming off the sump has two taps as bypass. I found the oil gums it up otherwise. I will put pics up later.
        Last edited by CNGLO; 05-27-2015, 05:14 PM. Reason: TOS language violation

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

          brit do your other gas appliances function with the compressor running?

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

            Originally posted by BritCNGUser View Post
            Yes, sits at 21mBar, see previous pic of the thing. Regulator is not the issue, (I ahd hoped it would be) we tested it, and it was that test that revealed the regulator doing its job, but starvation of gas meant it could not maintain the 21mBar. My previosu tests witha digital manometer had not shown what was truly happening because those things can't indicate like any plain 'old skool' gauge.

            Flatracker wrote:


            I have now got a pro on it. But are you sure about your method, the pro I spoke to fills with water to deprive the propane of oxygen. He has argon handy too and will fire some into the cylinder if need be. He said in the past he has done it barnyard-mechanic 'stylee' (as that thread also suggests) tubing a lawnmower or car exhaust into tehm. Carbon Monoxide will purge the oxygen,so gas present or not it simply can't burn. Adding more air will purge it well, but not limit the metal-trapped gases. He said leaving the cylinder water filled will have the propane absorbed by water. [this I am suspect of]

            Anyway the Coltri is vindicated. Deprivations of gas knocked down the pressures in cahin-raction, causing heat and thus dropping initailly the 2nd stage and then the 3rd. It is why I was chasing my tail all this time. Only proper flow & pressure gauges on input showed what was really happening. I am about to put a 30 gall ex-propane cylinder on the input for several reasons, one not least giving the blow-by gas somewhere to go at PU click-off. I see one helluva spike at PU click-off. The ex-propane cylinder can't solve my starvation issues btu I can't wait to see how my pump runs for a minute or two at start-up with the big tank in the line.

            I have permanently plumbed in flowgauges now. Teh oen coming off the sump has two taps as bypass. I found the oil gums it up otherwise. I will put pics up later.
            ok brit have you plumbed a gauge in the the line from the street before the regulator? if so what is the pressure with the your compressor running and what is the pressure after the regulator at the same time. what you are looking for is a pressure drop if you have one you need a larger orfice or a bigger regulator can you post a photo of your meter and gas co regulator? I would think that a 3/4 pipe would feed your compressor but most regulators have a orfice that is much smaller than the pipe size so you may only have a 1/4 or 1/2 in orfice and at those low pressures could never flow the gas you need and this is free to check and only a few dollars to fix. it would be nice to have a orfice as big as the pipe feeding it IE 3/4
            Last edited by cowboy; 05-21-2015, 07:43 PM.

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

              I am convinced I have a restriction. The jury is still out as to where largely because my inlet gauge sits 6 inches away from the Coltri input port. I am able to see the effect of various permutations added or removed from the input and the effect on my flowgauge and pressure gauge. I will put up a pic but if you can imagine, I have a permanently plumbed Dwyer gauge and a flowgauge sitting at the entry point to my MCH5.

              I took an identical type regulator and put it directly onto my flowgauge input. I still saw 150 l/min on my O2 scalse flowgauge and it tops out at 150l/min so it was pulling a bit more I think. The flow and PU time (2min 43 secs with lots of filters etc pulling air) ) was unaffected. Thus I conclude that unless 'their' regulator is faulty, the bottelneck is not this type of regulator. I would like to test 'their' regualtor in the same way, but there are tamper seals on the meter end of my supply for obvious reasons. With the test regulator now removed, next I hooked up the pipe coming from to my meter to the Coltri. At the same time disconnecting this pipe from the meter. So now I have about 20-25 foot of copper pipe + my flowgauge etc hooked up to the Coltri input, but i unhooked the meter end of this pipe so that I can test just the (3/4") pipe. I saw an appreciable drop in flow (down to 120 l/min, but PU time now increased by only 5 secs to 2mins 48 secs pulling air) so I conclude there is a restriction in that pipe. Now, is this because of that amount of pipe jsut gives that amount of choking or do I have a clumsy bit of pipe bending under my floorboards choking it off. This i am to check next. I then hooked it all up again, as would be in noraml use thus testing the meter and their regulator. I saw a furhter drop in flow but not so severe. Hence I now begin to think contrary to my earlier thoughts [because I had not tested solely the pipe before], that the restriction is after my meter. I need to put anothe gauge on at the meter-end test point as well as at the Coltri end (with the Dwyer) when running to see where the pressure drop occurs. The pressure drops form 21mbar to 10-11mBar at the Dwyer, [Coltri end]. To be tested but if there is no appreciable drop at the meter-test point, I have a pipe issue. This would possibly expalin why my other appliances are happy with the Coltri running., although not necessarly. Equally my gas-fitter tells me the street pressures got reduced, but hat could be a red-herring. I am told the street prssures are very low. This I get to verify next.

              Now I have no oil-cosumption to speak, of, my stages are above Coltru spec and it runs. Much as it did when new. But that restriction wherever it is will pull it down again if I don't find it. Because last time it pulled stopped the 1st stage seating . Which in turn pulled everything down in heat.

              To be continued...
              Last edited by BritCNGUser; 05-22-2015, 10:26 PM.

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

                how many feet is the it from the meter to the compressor? remember you can not have too big a pipe supplying the compressor.90s are bad if you must have them use 2 45s . I have fixed zero pressure regulators that when insalled had a handful of 90s and other fittings just by doing away with all the fittings and using a large hose I dont remember who told me that4 90s are a plug at zero pressure. at the pressure you are fooling with is dang close to zero pressure try taking a dremel tool and grind all the pipe ends that face the meter out to where there is no flat end on the pipe to create turbulence. make sure that you get all the grindings out I have had regulators fail so it could be the gas company's has failed or if they lowered the street pressure you would need a larger orfice. I have a gauge on my gas meter on the outlet. I just drilled and tapped a 1/8 hole in the pipe coming out and screwed a gauge in. now the pipe coming out is your pipe I also have a gauge on the supply line just after the gas cock on their side but keep in mind we have a good relationship with our gas company and get most anything we want. yours might get mad if you drill their pipe on there side but your side I would have a gauge if it drops then call them and get a bigger meter. as at lower pressure will require a bigger regulator and meter

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

                  when reassembling make sure to press the rear bearing in fully (i used a arbor press) and then make sure the race on the crank shaft is full inserted into the bearing before final assembly otherwise there will be alignment issues when installing the cylinders

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

                    Cowboy- Your experiece reinforces my hunch. I have count 'em 13, yes 13 ninety degree turns I can see.I dare not think how many I have under the floorboards to add to the 13. And all 3/4 copper, and I'll bet none have been deburred after the pipe-cutter has chomped them, and you have to be correct, at such low pressures, that'll be the issue or a fair way to it. I would love to tap into 'their' pipe to be sure of 'their' pressure. Not an option without involving the utility and they can be quite draconian. Best not upset them. I have a test point on tehe meter (on my side only), I need a second analogue manometer to test here which i will ahve soon. I think the lot has to be put to 1" pipe and 45s.


                    trdscfjc: Page 33! Reckon we need a rebuild thread, an input requirements ballast tank thread and any number of separate issue threads all feeding from this one!
                    Last edited by BritCNGUser; 05-24-2015, 04:29 AM.

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

                      13 nineties!!! You live in a maze???? Lol

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

                        Originally posted by BritCNGUser View Post
                        Cowboy- Your experiece reinforces my hunch. I have count 'em 13, yes 13 ninety degree turns I can see.I dare not think how many I have under the floorboards to add to the 13. And all 3/4 copper, and I'll bet none have been deburred after the pipe-cutter has chomped them, and you have to be correct, at such low pressures, that'll be the issue or a fair way to it. I would love to tap into 'their' pipe to be sure of 'their' pressure. Not an option without involving the utility and they can be quite draconian. Best not upset them. I have a test point on tehe meter (on my side only), I need a second analogue manometer to test here which i will ahve soon. I think the lot has to be put to 1" pipe and 45s.

                        !
                        I really think it's time to get a second dedicated meter from the utility and a 1" or the local equivalent home run to your compressor. your current situation is just not tenable IMO.Going to cost $$$, but good is usually not cheap and cheap is usually not good. A second reason: you stated a temporary spike in supply pressure when your compressor stops sometimes blows out the pilots on your appliances. This is a cleanly unsafe situation. They need to be on a supply line not shared with the compressor.

                        The only other solution would be a much smaller compressor, running longer hours. Slowing the compressor might be a solution, however, check with coltri, to see if the compressor has a minimum operation speed (for lubrication).
                        Last edited by Lakewood90712; 05-24-2015, 03:41 PM.

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

                          Lakewood has it right. For several reasons having got this isolated or as near a damnit this needs to be done properly. I will put in a ballast / receiver tank and additioanl regulators inline between compressor and other appliances - to both soak-up and/or cap the pressure spike getting to other appliances. If that doesn't work (and likely it might not) then I have to beef-up or twin the supply still more. This only to deal with the safety issues. [I quite like my body-parts arranged as they are]
                          To get the Coltri the supply it wants I will need to redo my supply pipework. I gained another 5-6 of those 90 degs putting in my flow-gauge to find out all this. This will need to be redone with a permanent solution. For kick-off it will need a flexible connector to the wall to isolate the vibration on pipes. Yup, What I have at the moment is a blinkin' 'maze' but also crass stupidity if I let it continue. I can assure you it will cahnge now I have an idea of what has been the cause. See pic for an idea of how mad it has got, ( i nearly vie with Karl for kit on there) but even if my pic uploaded inverted, I do have proper pressures.... at last.
                          Attached Files
                          Last edited by BritCNGUser; 08-01-2015, 04:52 PM.

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

                            brit post me a photo of your gas meter and regulator coming from the street the one that belongs to the gas company

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

                              Poking around on the net for UK gas meter regulators, most I see are designed for 75 max. milibar inlet pres. , so the street mains maybe 1 psi ? or so. A difficult spot to be in.
                              Last edited by Lakewood90712; 05-24-2015, 08:27 PM.

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

                                I'm about to clear off on hols with my boy so you'll not see me on here for a week but Lakewood has it right, 75mBar is at best what I have to work with. In fact my gas fitter says I have half that in the street if I'm lucky. The Coltri works down to 17mBar. No pic handy now but, fed vai a 3/4" pipe, I have the standard UK G4 meter with a Jeavons J42. Standard UK domestic kit. Meter and reg are happy up to about 7.5m3 (I flow tested it to this - spec is 6m3) but the supply I suspect isn't or it might be my 13+ nineties! Down a 3/4" pipe at 21mBar I am right on the edge of what the Coltri needs. Even 6m3 is a lot of gas for a home, not so much for us. Be back next week.
                                Last edited by BritCNGUser; 05-25-2015, 12:51 AM.

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