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  1. #1
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    Large diameter pressure fittings

    I'm putting together equipment to treat bamboo and have reached a stumbling block. The process requires a borax solution to be fed at pressure to base of the bamboo pole. The pressure is 1 - 1.5 bar (15 - 20 psi) and the bamboos are 4" - 6" in diameter.

    I've used 4" pressure PVC and adapters, but it ends up being a long awkward fitting and I'd like to find something shorter. It's also very difficult to find rubber fittings and clips that can adapt to the varying diameters of the bamboos. I've been using inner tubes, which tend to balloon and pull away, although I think I cam solve that.

    Below are some fittings used by others. The taps at the top are needed to drain the air when feeding the borax.

    I'd like to have some similar fittings made up, preferably in steel. Galvanized piping is way too heavy. I've been thinking about using old fire extinguishers cut in half. Any suggestions?


    These are plastic pressure fittings, unfortunately I can find short plastic fittings like these.


    Here are some steel fittings:





  2. #2
    disturbance in the Turnip baldrick's Avatar
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    maybe a steel sleeve wrapped around the rubber and then clamped.
    get some thin shim sheet , put the rubber on first , then wrap the shim around so there is a small overlap , then put on your hose clamps.

    the other option too is to use the thick hose but it does not give you much leeway for different diameters of bamboo.

  3. #3
    Member tuktukdriver's Avatar
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    How about neoprene, the wetsuit material. You could sew and glue it to make a sleeve, just like they do for dive suits, then stretch it around the pole, then clamp on it.

  4. #4
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    Thanks for the suggestions, I've got some strong 40mm wide clamps that should provide a seal. Together with tough fabric they should prevent balloon and pulling away...I hope.

    I'm really looking for some better fittings though, the PVC ones are all tapered and several are needed to reduce from 4" to 1/2". You end up with a huge awkward fitting.

    Anyone got suggestions what could be used and how such fittings could be made? I'd like them to be at least 5" diameter.

  5. #5
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    instead of pressure treating it have you tried osmosis or gravity?

  6. #6
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    Quote Originally Posted by splitlid View Post
    instead of pressure treating it have you tried osmosis or gravity?
    Gravity is very slow, I'm not sure about Osmosis. I've done a lot of research and the system I'm using is effective and low cost, I'm just at a bit of a stumbling point with the connections.

  7. #7
    disturbance in the Turnip baldrick's Avatar
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    Quote Originally Posted by Smithson
    the PVC ones are all tapered and several are needed to reduce from 4" to 1/2"
    what are the 1/2 inch fittings that you are using ? BSP , BSPT , NPT ?

    have you thought about getting a 4" cap or plug and the drilling and tapping the thread you need for your 1/2" fitting ? remembering you will need about 1/2 - 3/4 " of thickness to thread into.

  8. #8
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    Quote Originally Posted by baldrick View Post
    Quote Originally Posted by Smithson
    the PVC ones are all tapered and several are needed to reduce from 4" to 1/2"
    what are the 1/2 inch fittings that you are using ? BSP , BSPT , NPT ?
    They're Blue PVC.

    [quote=baldrick;943513]
    Quote Originally Posted by Smithson
    have you thought about getting a 4" cap or plug and the drilling and tapping the thread you need for your 1/2" fitting ? remembering you will need about 1/2 - 3/4 " of thickness to thread into.
    Do you mean a PVC cap? I haven't seen any that are for pressure pipes, it's all for waste. If you mean steel, I'd be interested in what type and where I can find it. The gal piping is too heavy and not quite large enough. Copper would be OK if I could find an off cut, I used to to water mains for high rise using up to 6mm copper.

    I was thinking about cutting an old fire extinguisher in half and using that. It could actually fit over the bamboo and be held with screws, a little like the pic below:

  9. #9
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    What about a rubber funnel.

    Rubber Funnel


    Another option might be cutting off end of larger coke, pepsi or other such bottles.

  10. #10
    disturbance in the Turnip baldrick's Avatar
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    looking at your photos i notice you re using clear plastic tubing - what is it rated to 15 PSI ?

    are the photos of your setup ?

    I notice some of the setups are using industrial air/water hose for the connection to the bamboo, which should handle 100PSI easily.

  11. #11
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    Quote Originally Posted by baldrick View Post
    looking at your photos i notice you re using clear plastic tubing - what is it rated to 15 PSI ?

    are the photos of your setup ?

    I notice some of the setups are using industrial air/water hose for the connection to the bamboo, which should handle 100PSI easily.
    It's not my set up. The hoses going from the top are only to drain air, they're not under pressure.

    At some stage I may have to have fittings made up from 5" steel. Any idea where I could go for this? Most of the welding done locally is pretty rough. It'll also be difficult to find 5" pipe. I need something that won't corrode. I haven't had good experience with Thais doing specialist type work.

  12. #12
    disturbance in the Turnip baldrick's Avatar
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    Quote Originally Posted by Smithson
    At some stage I may have to have fittings made up from 5" steel.
    get it done in Stainless maybe , get endcaps welded on and either supervise drilling and tapping the thread in the endcap for your 1/2 fittings or do it yourself.

  13. #13
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    Any idea where I could get stainless done that would could cope with the pressure?

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