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Re: [tracker2] OT question...

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  • Wes Johnston, AI4PX
    We have two gensets. We can run them 50:50 when deployed. We actually started out with one, but the local FD at a week long fire we went to gave us the 2nd.
    Message 1 of 5 , Nov 9, 2006
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      We have two gensets.  We can run them 50:50 when deployed.  We actually started out with one, but the local FD at a week long fire we went to gave us the 2nd.  The booger about the other genset is that there is no standard for "key faces in" or "key faces out" for the 4 pin twist and lock connectors and wouldn't you know, each genset we have is different.  I just want keep tabs on the one that is running so we don't get an unexpected power outage.  We seem to get about 12 to 14 hours on a tank of fuel with the AirCond running however, not too bad. 
       
      Reallly OT: I wired the lights in the trailer so that we have redundant fixtures... 120v compact fluorescents and 12v CFs from a marine supply place.  We have two light switches which are labeled 120v and 12v.  I had wanted to have a failsafe relay that dropped us to 12v lighting when ac power was off, but never wired it in.  We used 50amp power poles that are yellow for the AC power inlets under the trailer.  I've made a set of 4 pigtails that allow running from 110 or 220 (I run everything on one phase, and the AirCond unit on the other phase when on 220v).  The pigtails allow us to run from either genset, a 110v extension cord or a 220v plug.  I've wired the chassis of the trailer as ground, and ironically the first time we used the trailer, the outlet we plugged into was not grounded and we had 110v @ 48mA on the frame of the trailer.  We now carry grounding rods with us and grounding the trailer is a part of our SOP.
       
      Wes

       
      On 11/9/06, Curt, WE7U <archer@...> wrote:

      On Thu, 9 Nov 2006, Wes Johnston, AI4PX wrote:

      > If I had a small 6kw genset that was to be run outside our comms trailer,
      > how would I remotely see the fuel level? I've thought about putting a 0-10"
      > of H2O pressure transducer at the fuel feed at the bottom of the tank, but
      > they seem kinda pricey at $100 from grainger. Are there other sources?
      > Other methods? This is the normal el-cheap-o genset you get from lowes or
      > home depot with the shallow fuel tank on top of the frame.

      I'm not going to directly answer you question ('cuz I don't know the
      answer!) but I wanted to mention something else about this:

      If the gen-set has a small tank, usually they also have restrictions
      against running it continously. This engine design is supposed to
      cool down between runs, then you can fill it and start it up again.
      These types typically don't have the proper cylinder design for long
      run-times, and in fact will need an engine rebuild after XX number
      of hours (and it ain't all that long!).

      If it has a larger tank it most likely can be run for extended
      periods, but of course they still warn you not to fill it while it
      is running. I have one of these types, a Devilbiss 5000 or 6000W.
      It has a larger tank that goes across the top of nearly the whole
      unit.

      I understand what it's like to be on a mission and have everything
      in the comms truck go dark at 3am when the gen-set runs out of gas.
      Just be careful with the cheap type as you might seize it up or at
      least severely decrease the operating life if you try to run it
      continuously.

      Anything further on this topic will undoubtedly be beyond my
      knowledge/experience. I learned most of the above from a friend,
      now deceased, who knew _much_ more about generators than I did.
      He mentioned that the tank size was the major indication of the type
      of cylinder and whether the system could run in continous duty. The
      other indication would of course be the owner's manual.

      --
      Curt, WE7U. APRS Client Comparisons: http://www.eskimo.com/~archer
      "Lotto: A tax on people who are bad at math." -- unknown
      "Windows: Microsoft's tax on computer illiterates." -- WE7U
      "The world DOES revolve around me: I picked the coordinate system!"




      --
      Where there's silence, there is no Hope.
    • Greg Merkley
      The one other method I ve seen uses a vertical tube off the side of the tank that fills with gas to the same level as the tank. A magnet is floated inside the
      Message 2 of 5 , Nov 9, 2006
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        The one other method I've seen uses a vertical tube off the side of
        the tank that fills with gas to the same level as the tank. A magnet is
        floated inside the tube with magnetic reed switches attached at various
        heights along the tube. If the magnet is at the height of one of the
        switches then that one is closed while the others are open. It gives a
        good enough, but not super accurate measure of the fuel left in the tank.

        -Greg VE7GJM

        Wes Johnston, AI4PX wrote:
        > If I had a small 6kw genset that was to be run outside our comms
        > trailer, how would I remotely see the fuel level? I've thought about
        > putting a 0-10" of H2O pressure transducer at the fuel feed at the
        > bottom of the tank, but they seem kinda pricey at $100 from grainger.
        > Are there other sources? Other methods? This is the normal el-cheap-o
        > genset you get from lowes or home depot with the shallow fuel tank on
        > top of the frame.
        >
        > Wes
      • Curt, WE7U
        ... That s really a slick way of doing a non-contact sort of sensing. If you attach a small magnet to one end of each reed switch, they ll latch as the magnet
        Message 3 of 5 , Nov 10, 2006
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          On Thu, 9 Nov 2006, Greg Merkley wrote:

          > The one other method I've seen uses a vertical tube off the side of
          > the tank that fills with gas to the same level as the tank. A magnet is
          > floated inside the tube with magnetic reed switches attached at various
          > heights along the tube. If the magnet is at the height of one of the
          > switches then that one is closed while the others are open. It gives a
          > good enough, but not super accurate measure of the fuel left in the tank.

          That's really a slick way of doing a non-contact sort of sensing.

          If you attach a small magnet to one end of each reed switch, they'll
          latch as the magnet passes by. They'll look like this when near
          full:

          (Bottom) (Top)
          1 1 1 1 1 1 1 1 0 0


          Or this when near-empty:

          (Bottom) (Top)
          1 0 0 0 0 0 0 0 0 0

          I suppose for your purposes you really only need one magnet/reed
          switch combo and one magnet in the line, letting you know it's at
          1/4 tank or 1/8 tank or something. Attach that to a flashing 200W
          light bulb in the command-post or a red-alert klaxon or something...

          You could also have the tube come off the bottom of the tank, go
          vertical for a while, then have it go back into the tank, so you
          don't need to have a separate air vent at the top of the tube.

          By the way, if you're looking for some cool small rare-earth
          magnets, I just bought a bunch from amazingmagnets.com to play
          with. If you buy any of the larger ones don't get your fingers
          between them as they come together. It took my index finger a week
          to get rid of the bruise I got when two of them pinched me
          unexpectedly. They're much faster than I am.

          So, to stay on-topic, hook the magnet/reed-switch combo to an
          OpenTracker and send the alert to the command post that you're about
          out of gas.

          --
          Curt, WE7U. APRS Client Comparisons: http://www.eskimo.com/~archer
          "Lotto: A tax on people who are bad at math." -- unknown
          "Windows: Microsoft's tax on computer illiterates." -- WE7U
          "The world DOES revolve around me: I picked the coordinate system!"
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