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Revell Type VII SAS system float-valve

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  • Revell Type VII SAS system float-valve

    Hi, I just want to ask you, how perfect should seal the safety float-valve? After a year of slowly building my type-7, I am in trimming phases. And during the tests I found that float-valve for sealing dry hull do not seal so good. It works in 70-80 percent: in case of low pressure in dry hull and opened snorkel head-valve (under water of course) means that little flush of water continuously flow to battery space. That’s not great, because in this case the safety valve is not so safety. Yes, there must be a combination of accidents, but Murphy’s laws works perfectly. So back to question – how watertight should be the valve from design point of view?
    Thanks
    L.

  • #2
    You're right, the safety float-valve should work ALL THE TIME. And your testing protocol is a good one -- it identified the problem under real-word conditions. I applaud you for that. No, we don't want any water, as a constant stream, to get into the boat. However, as Manfred pointed out, a drop or two will get by the safety float-valve, so you should account for that.



    Sounds like something is fouling between the rubber seat and pick-up tube within the safety float valve. Remove the inlet and outlet flexible hoses from the safety blow valve and blow medium pressure air through the outlet nipple of the safety float valve as you invert and set upright the SD -- this will work to knock off any foreign matter that got onto the internal rubber element. Reatach all plumbing and test as before.



    If the blow-down fix does not work, remove the safety float-valve, remove its head, and clean and re-apply grease to the rubber element. Reassemble and test.

    Let me know how that works out for you, L.

    David
    "... well, that takes care of Jorgenson's theory!"

    Comment


    • #3
      Ligamin, You can buy one of those dishwashing sponges and cut a piece out of it and slide it into the bottom of the Subdrivers engine compartment and it will take care of that excess water by containing it. Its not uncommon for full size ships and submarines to have small leaks. Thats why they have bilges and bilge pumps.
      Last edited by greenman407; 02-08-2016, 06:03 PM. Reason: more jawing needed to be done.
      IT TAKES GREAT INTELLIGENCE TO FAKE SUCH STUPIDITY!

      Comment


      • #4
        @ David: Ok, there are result of yesterday’s tests. I removed safety float-valve from the dry hull tube. By helping 10ml syringe (hmmm, 0,33oz? sorry) I did simulate low pressure in dry hull. When the valve is dry (the valve body do not contain water), I am able suck up half and more of syringe. Ok, I return water to cup and try it again. And there a) the same situation –or- b) some water remains in valve body and the valve is watertight instantly after start of sucking. In case B the valve is so tight that I am not able suck even air. It looks like the floater is jamming in the valve body. So did try remove head, but it is so tight – how much of strength I should use? I don’t want damage the whole body…
        @ greenman407: Sponge could help save a water, but the pipe from float-valve enter directly above of batteries. So they have a nice shower :) Maybe I could enter them into some rubber balloon. I am thinking about another device, some retention basin, which have functionality store a bit of water and expand stored air in dry hull. Some addon. :)

        L.


        Comment


        • #5
          Originally posted by Ligamin View Post
          @ David: Ok, there are result of yesterday’s tests. I removed safety float-valve from the dry hull tube. By helping 10ml syringe (hmmm, 0,33oz? sorry) I did simulate low pressure in dry hull. When the valve is dry (the valve body do not contain water), I am able suck up half and more of syringe. Ok, I return water to cup and try it again. And there a) the same situation –or- b) some water remains in valve body and the valve is watertight instantly after start of sucking. In case B the valve is so tight that I am not able suck even air. It looks like the floater is jamming in the valve body. So did try remove head, but it is so tight – how much of strength I should use? I don’t want damage the whole body…
          @ greenman407: Sponge could help save a water, but the pipe from float-valve enter directly above of batteries. So they have a nice shower :) Maybe I could enter them into some rubber balloon. I am thinking about another device, some retention basin, which have functionality store a bit of water and expand stored air in dry hull. Some addon. :)

          L.

          The body and cap are secured and made watertight with RTV adhesive -- which will part with a little torque. Don't worry about scratching the safety float-valve body and cap.

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          Grasp the body with pliers; grasp the head-cap with another set of pliers; twist; and separate the two. . After you clean off the rubber element (find out what's making the float hang up in the body and fix that first), apply some thick silicon grease to the rubber element and re-asseble. Use fresh RTV sealant to bond and make watertight the unit.

          David
          "... well, that takes care of Jorgenson's theory!"

          Comment


          • #6
            Hi, ok, I opened the float-valve. I didn’t find any jamming issue, dust, etc.
            So I cleaned it and shine inner space (the float move smoother), apply silicon grease as you advised and re-assembly. The sealant was a little problem, because I did use one which was not so good (for metal), but the second one (what I have) fix the head to body well and watertight.
            Test phase. Ok, the functionality looks much better. However there are some hints to discussion.
            When I press the water (I am apologize, English is not my native language…) from bottom manifold slowly then – in most cases - works well and pass about 1ml of water, or (occasionally) close immediately. If I press water more quickly, the floater don’t react so fast and pass everything (10ml in my case).
            When I suck the water from upper manifold (it is more nature to situation I think), the floater close the vent immediately (in most cases) or pass about 1ml too. The speed of sucking has influence too, but not so high.
            So, it is about float reaction. I thought about some diameter restrictor (to slow water but not the air) and about some expansion tank addon (to store water and increase air capacity). By the way, the pump, how many litres of air per minute is able pump up?

            Photo link below

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