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  • Air over Hydraulic Vessel question

    Knowing bugger all about this ..and not willing to spend £100 plus each for new injectors ...or £10 each for so called refurbished (cleaned) injectors

    i intend to make a vessel ...to test fuel injectors ...one at a time .

    I'm more interested weather i can clean them with ultra sonic tank whilst pulsing them with DC and stop them dripping, than the spray pattern ..sinse my car runs on LPG not petrol.

    so have a look at this diagram ...it wont necessarily contain petrol ..maybe kero



    all i have is "dry air gauges" so cant measure the liquid pressure ..

    1...will the air pressure multiply or decrease the hydraulic pressure
    2 can i expect around about 45 psi out of liquid pressure to the 45 psi of air ..
    3,if not what air pressure into ...a vessel.........(you can make up the size of vesel) ..will be required to get 45 psi out the other end.

    BEAR IN MIND WHEN ANSWERING ...

    that my supplies are limited to max of 3 inch or there abouts diameter thick walled pipe for the vessel....and max air pressure I'm willing to give to it is 90 psi

    all the best.markj

  • #2
    You will get 45psi out.

    Comment


    • #3
      What kind of pressure do you want ?

      Why not a gear pump driven with an electric motor ?
      Kero lubricates enough for a gear type pump (I believe)

      Maybe get a used power steering pump from the wrecking yard,
      lower down the pressure relief setting.

      why not a carbonator pump ? also used as water pumps
      on tig torch coolers, but the proliferation of soda fountains
      has lowered the cost on these.

      The air tank system, look at a paint pot, ready to go,
      has a quick opening top for filling, and has a safety valve
      built in.

      Comment


      • #4
        To get pressure multiplication you need a stepped piston (change in diameter) between the air and liquid

        Comment


        • #5
          PEOPLE ARE MISUNDERSTANDING THE QUESTION ..
          I WANT 45 PSI LIQUID PRESSURE

          i have at my disposal ...air pressure to 90 psi
          a lathe and milling machine to make the vessel
          materials to make the vesel ...why would i want to go out and buy a pump ?

          there is no multiplcation going on ..according to marks answer ..he answered it ..unless others know different

          all the best.markj

          Comment


          • #6
            You will get 45 psi out.
            Dry gauge, wet gauge, it does not matter...pressure is pressure, it does not matter.
            An air gauge will read hydraulic pressure and vice versa, all that matters is that the gauge has the right pressure range.
            Home, down in the valley behind the Red Angus
            Bad Decisions Make Good Stories​

            Location: British Columbia

            Comment


            • #7
              Electric fuel pump from a car with a rail injection system(45-60psi) and a fuel pressure regulator with a tank return.This will allow pressurizing the fuel directly with out the need for air in an accumaltor at pressure.

              Pressurized air and fuel in a sealed container is a bad idea,flaming death comes to mind.If you must build what you have drawn,please use CO2 or Argon and not compressed air.
              I just need one more tool,just one!

              Comment


              • #8
                "PEOPLE ARE MISUNDERSTANDING THE QUESTION ..
                I WANT 45 PSI LIQUID PRESSURE "

                Stop shouting, we are trying to help you

                "i have at my disposal ...air pressure to 90 psi
                a lathe and milling machine to make the vessel
                materials to make the vesel ...why would i want to go out and buy a pump ?"

                Well now, because some of us have done these things before, and
                the road your going down has problems. Problems we didn't
                include in our post's.

                Just like the litlle snippets of info you didn't include in your question.

                Comment


                • #9
                  Originally posted by wierdscience
                  Pressurized air and fuel in a sealed container is a bad idea,flaming death comes to mind.If you must build what you have drawn,please use CO2 or Argon and not compressed air.
                  OK will bang argon into it then ...
                  any hows, what do they use for propellant of aerosol cans containing ..wd40 ,paint , hair lacquer.
                  edit ...and come to think of it every spray gun ...im not talking hundreds of psi here ..that is needed to compress diesel to ignight ...and have said will not do it on petrol ..

                  and im with out any transport ...so cant go hunting around for fuel pumps .

                  all the best.markj
                  Last edited by aboard_epsilon; 04-16-2009, 09:29 AM.

                  Comment


                  • #10
                    Pressure X area = force. Figure it out. Simple physics lifts heavy objects.

                    Comment


                    • #11
                      What most are alluding to but saying in different ways Mark is that when you do pressure "TESTS", Hydraulic is good, Air (or ANY gas) is bad. Much SAFER to have a liquid pressure system between the liquid and the "Nozzle" Yer can't compress a liquid, but you can a gas and therebye hangs the problem.

                      Regards Ian.
                      Last edited by Circlip; 04-16-2009, 09:36 AM.
                      You might not like what I say,but that doesn't mean I'm wrong.

                      Comment


                      • #12
                        Originally posted by moe1942
                        Pressure X area = force. Figure it out. Simple physics lifts heavy objects.
                        This is very true but how does it relate to the current question?

                        Comment


                        • #13
                          Its all possible - but!!! or if!!!

                          Mark.

                          This may be a bit OT, but my car has dual fuel - Petrol (UK and OZ - "gas" in the US) and LPG.

                          My car starts on petrol and that switches off as I release the "start" on the ignition key when the engine starts and then it runs on LPG.

                          I asked my Mechanic about failure of the petrol system and he said that the car would start OK on LPG but it would be a bit harder - more so in Winter than Summer.

                          My older LPG system has the LPG delivered into the intake manifold on the engine side of the throttle disc and so is the same as a non-injected car (ie normally aspirated). The petrol is injected from the rail directly into the cylinders.

                          On my system the fuel system is on and running even when I am running on LPG.

                          If your petrol pump were to switch off with your "start" switch there should be minimal pressure in your fuel system and rail and injectors and so there will be minimal dripping.

                          I'd guess that if your injectors are dripping through wear that cleaning them won't cure them. But if they are leaking because of a contaminated fuel (petrol system, including the tank, pipes, rail etc.) then even if they are cleaned it won't be long before they are fouled and dripping again.

                          My point here is that if your car is anywhere similar to mine that at least you can use it until you find out what is really wrong and do something about it.

                          Its your call after all.

                          Comment


                          • #14
                            If all you want to do is test a few injectors to see if they leak, the setup you describe is completely sufficient, provided you do a reasonable job of welding up your pressure vessel.

                            I just finished a fixture for leak testing diesel locomotive injector coils at 1100 psi using 90 psi shop air. It involved using a 3" air cylinder to push a 3/4" hydraulic cylinder for pressure multiplication. The area under pressure is so small that the leaks, when they happen, aren't very exciting.

                            Speaking of pressure vessels, I once loaned a 1000 gallon steel tank to an idiot to use as a temporary water reservoir while he was doing some well work. Seems that the water wasn't draining out of the tank fast enough for the idiot so he hooked up his compressor to "force" the water out faster. The tank held up but was shaped like a football when I got it back. Idiot...
                            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                            ~Practitioner of the Electromechanical Arts~

                            Comment


                            • #15
                              From yer sketch Mark, you're quite close to re-inventing a blowlamp.
                              You might not like what I say,but that doesn't mean I'm wrong.

                              Comment

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