another vacuflush question discharge
- Thread starter risingson
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I have two pumps one for the vaccum and another for discharge, both look the same, they are not the jabsco marcentor pumps, they are the sealand
bellows pumps.
The discharge pump has been working all summer, I test it every week. Just last week I am unable to discharge overboard. Does the overboard pump have duckbills in them as the vaccum pump and can these stop the discharging process? Also does the discharge pump create a vaccum?
The pump is running and the bellows is moving
just nothing coming out of the bottom of the boat.
bellows pumps.
The discharge pump has been working all summer, I test it every week. Just last week I am unable to discharge overboard. Does the overboard pump have duckbills in them as the vaccum pump and can these stop the discharging process? Also does the discharge pump create a vaccum?
The pump is running and the bellows is moving
just nothing coming out of the bottom of the boat.
Capt. Bill1
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The overboard pump has 4 duckbills in it. The pump out pump does not create a vacuum. It just pumps out the holding tank.
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actually the overboard pumps have 2 duckbills, the vac pumps are the one with 4. it will build some vacuum but not hold it as well as a vac pump.
if the motor turn, make sure the bellows move. sometimes the set screw on the shaft can work loose. if the bellow moves, and your seacock is open, it could be the duckbills,check that out.
that said, you do realize that CT and LIS is all no discharge so even testing your pump is illegal unless you go 3 miles out the race? your seacock must remain closed AND locked (or handle removed) unless you have a key switch on the pump (and the key isn't kept in)
if the motor turn, make sure the bellows move. sometimes the set screw on the shaft can work loose. if the bellow moves, and your seacock is open, it could be the duckbills,check that out.
that said, you do realize that CT and LIS is all no discharge so even testing your pump is illegal unless you go 3 miles out the race? your seacock must remain closed AND locked (or handle removed) unless you have a key switch on the pump (and the key isn't kept in)
Capt. Bill1
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2-4, it's all the same s#$t in the end. 
I doubt the duckbills would be responsible for your discharge not working unless they are really clogged up. The purpose of the duckbills are to prevent backflow and do not affect operation of the pump.
It might be pretty simple - check your pumpout fitting and make sure it's properly sealed. The pumpout and discharge lines are often split from the same pipe leaving the holding tank and if the pumpout fitting is leaking air, the discharge will simply suck air from there rather than pick up the contant of the holding tank (path of least resistance).
It might be pretty simple - check your pumpout fitting and make sure it's properly sealed. The pumpout and discharge lines are often split from the same pipe leaving the holding tank and if the pumpout fitting is leaking air, the discharge will simply suck air from there rather than pick up the contant of the holding tank (path of least resistance).
I use the same pump for my discharge. The pump has to pull waste up from the bottom of the tank.I have a sensor on my tank that switches of the pump just before the pump starts to suck air. In this situation all is always ok. If I manually over ride the sensor and allow the tank to pump totally dry, I then will often have problems with the pump re priming. The duck bills over time tend to take a set that keeps them slightly open.They sometimes develop small cracks down the sides, I have also seen them split away from the mounting flange. Another problem with them is if the head is used to dump any type of oily substance. The oil softens the rubber. They make a different duck bill for use if the pump is used for bilge work. It uses a non oil effected material but they are not recommended for sewage. Any of these problems, allows the air in the intake side to simply move back and forth instead of pulling a new gulp each stroke.
Bazza
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It's usually the duckbills, if the discharge pump isn't pumping. With the vacuum pump, it could be several things but not with the pump that empties the holding tank - that's almost always the duckbills.
Etienne, in the case of a SeaLand pump the duckbills work in concert with one another, to direct the flow out of the pump. If either (or both) of the duckbills isn't sealing properly, the pump won't pump. You're thinking of a Crown head or other head, where the duckbill is used as an anti-backflow valve. In a pump, where two (or 4) are used, they perform a different function.
Etienne, in the case of a SeaLand pump the duckbills work in concert with one another, to direct the flow out of the pump. If either (or both) of the duckbills isn't sealing properly, the pump won't pump. You're thinking of a Crown head or other head, where the duckbill is used as an anti-backflow valve. In a pump, where two (or 4) are used, they perform a different function.