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  1. #1
    Join Date
    Jun 2005
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    London
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    2,188

    Default How does a marine toilet work?

    I have a Raritan PH Superflush manual toilet. I wonder how it works. It has a pumpy handle and two settings, "flush" and "dry". I do understand that when turned to "flush" that water is pumped in to the bowl. However, I cannot find a plan to show how the pump, pumps waste out of the toilet while pumping water into the bowl.

    Thanks

    TudorSailor

  2. #2
    Join Date
    May 2001
    Location
    UK East Coast
    Posts
    34,017

    Default Re: How does a marine toilet work?

    All these manual toilets work in essentially the same way. The pump chamber has a piston, with sea water above it and waste water below it. When you pull the handle up, waste water is drawn into the lower part of the pump and sea water is pumped out into the bowl. Then, when you push the handle down, the waste water is expelled into the discharge pipe, and more sea water is sucked in to the upper part of the pump. The flush/dry lever controls a little valve which stops sea water being sucked in to the pump.

  3. #3
    Join Date
    Sep 2006
    Location
    Oslo, Norway
    Posts
    1,457

    Default Re: How does a marine toilet work?

    The pump is a piston pump, it uses one side of the piston to empty the bowl the other side is used to pump sea water.
    In dry possition the valve on the flush side is blocked in open position

    Edit:
    pvb typed faster than me....
    Last edited by knuterikt; 05-08-16 at 16:48.

  4. #4
    Join Date
    Dec 2003
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    4,939

    Default Re: How does a marine toilet work?


  5. #5
    Join Date
    Jun 2009
    Posts
    11,878

    Default Re: How does a marine toilet work?

    My only observation on the above is that they seem to be designed so that the volume of water pumped in on each stroke is rather more than the volume pumped out - otherwise you would not be able to fill the bowl with clean water.

  6. #6
    Join Date
    Jun 2005
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    London
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    2,188

    Default Re: How does a marine toilet work?

    Quote Originally Posted by dom View Post
    Perfect! Many thanks

    Will now get armed with equipment to see why "the waste goes out" but not much water comes in! I think I need a new O ring on the piston.

    TudorSailor

  7. #7
    Join Date
    Jun 2005
    Posts
    20,592

    Default Re: How does a marine toilet work?

    A better and a more interesting question would be " How Does a Marine Toilet Not Work?"
    If I'd wanted to live in a Banana Republic I'd have gone to South America.

  8. #8
    Join Date
    Sep 2006
    Location
    Oslo, Norway
    Posts
    1,457

    Default Re: How does a marine toilet work?

    Quote Originally Posted by tudorsailor View Post
    Perfect! Many thanks

    Will now get armed with equipment to see why "the waste goes out" but not much water comes in! I think I need a new O ring on the piston.

    TudorSailor
    could also be the valve on the inlet side, once I had the "coin" fall off the flap valve...

  9. #9
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    18,267

    Default Re: How does a marine toilet work?

    Quote Originally Posted by maby View Post
    My only observation on the above is that they seem to be designed so that the volume of water pumped in on each stroke is rather more than the volume pumped out - otherwise you would not be able to fill the bowl with clean water.
    Actually, the amount pumped out should be more than is pumped in, or flushing would not work. All the designs I have seen do this, sort of, by having the clean water side next to the handle; since the piston is on that side the swept volume is less by the full volume of the piston. It's not much, though.

    Quote Originally Posted by tudorsailor View Post
    I have a Raritan PH Superflush manual toilet. I wonder how it works. It has a pumpy handle and two settings, "flush" and "dry". I do understand that when turned to "flush" that water is pumped in to the bowl. However, I cannot find a plan to show how the pump, pumps waste out of the toilet while pumping water into the bowl.
    It's a while since I overhauled a Raritan (Compact, in my case), but from memory the "flush/dry" control rotates a small valve in the inlet, blocking off the flow of water. It's a rotten design, because the pressure differential which results gives you blowback past the piston and the inlet side gets contaminated. If yours is giving the slightest trouble I would recommend ditching it. A better replacement is a hundred quid or so.
    "Seamen are always wanting to do things the proper way; and I like to do them my way."

  10. #10
    Join Date
    Jun 2009
    Posts
    11,878

    Default Re: How does a marine toilet work?

    Quote Originally Posted by JumbleDuck View Post
    Actually, the amount pumped out should be more than is pumped in, or flushing would not work. All the designs I have seen do this, sort of, by having the clean water side next to the handle; since the piston is on that side the swept volume is less by the full volume of the piston. It's not much, though.
    ...

    .
    Not on a Jabsco, at least - if you set it to flush and keep pumping it will slowly fill up. You have to set it to drain in order empty it.

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