[Public-List] Holding tank vent

[George Dinwiddie]

Glenn,

On 3/4/13 11:06 PM, brooks.glenn at comcast.net wrote:
> John, Great question...
>
>
> I dont think one vent line can back fill. the ambient air pressure in
> a closed tank system will prevent sea water intrusion through the
> vent line. Certainly did (prevent backfill) in my fishing boat in
> Alaska, which had a fuel tank vent at the bow.
>
>
> But with two 3/4" vent lines, the back pressure in the tank is
> neutralized and it seems like water could then enter, particularly
> when bashing to windward. One of the vent lines would be in a gravity
> feed position above the tank, so conceivably could the tank be in a
> position then to syphon water back into the boat through the commode?
> A n asty result to say the least...

It's the low side that will go in the water. It won't flow by gravity, 
and I don't see how it will get a siphon going.

  - George

-- 
  ----------------------------------------------------------------------
   When I remember bygone days                         George Dinwiddie
   I think how evening follows morn;            gdinwiddie at alberg30.org
   So many I loved were not yet dead,           http://www.Alberg30.org
   So many I love were not yet born.                          also see:
                'The Middle' by Ogden Nash     http://idiacomputing.com
  ----------------------------------------------------------------------




 1362462661.0