SeaLand Macerator Pump - Inverted Duckbill Valves

[DeepFrz]

I have not personally used these but have read good reports.

Whale Marine - Products

[sailor1924]

Hi;
Did you try replacing the Jabsco screws with Stainless? I'm curious as I have a Jabsco macerator on my toilet and just replaced it wiyh new and would like it to last.

[peghall]

Any chance that you installed the pump backward? You wouldn't be the first person to do that...I can name half a dozen VacuFlush owners who removed their vacuum pump (same pump as the discharge pump, btw, just with two valve nipples on each end and 100% higher price tag) to replace the duckbills and put it back 180 degrees off. That's the only thing I can think of that would turn the duckbills inside out

[eyschulman]

I had a similar problem with one of my sea land pumps. I am suspicious of pump out causing the problem. I have valves before the pump and will close them before I try another pump out. The duck bills that were inverted had open valve before pump the other sealand had a closed valve and did not invert.

[HopCar]

It seems to me that your tank vent would have to be blocked for enough of a vacuum to form in the tank and invert the joker valves, when you use a dockside pump out.

[Scott Berg]

We love the SeaLand T pumps and have had almost no problems. We recommend replacing the DuckBill Valves at least every two years. They are easy to service. You MUST have a valve between the tank and any overboard pump or the shoreside pump out systems will either invert the duckbill's or pull the seals out of the Jabsco type pumps. Most manuals make this clear.

It's also a good idea to have a vacuum break on the holding tank in case of a clogged vent when using powerful shoreside pump-outs. Sealand sells a good one...

[Clamdigger62]

I had this problem after replacing a jabsco macerator with a SL T12. I used a 1" to 1 1/2 coupler at the discharge thru hole which also made a 90% bend. The flow was too much for the restriction and the pressure made the duckbills on the intake side of the pump to invert.
Installing a 1 1/2 thru hole solved the problem. The T12 is a great pump and pumps far more volume then the Jabsco but the Jabsco does liquidfy the waste better.

[peghall]

Originally Posted by Clamdigger62

I The flow was too much for the restriction and the pressure made the duckbills on the intake side of the pump to invert.

Only SUCTION from ahead of the pump could cause duckbills to invert (turn inside out) if they're aimed in the rright direction. Pressure can only cause it to happen if they're installed in valve nipple backward (material hits the slits end first instead of the wide opening, pushing them inward) or the pump was set down backwards....which is easy to do!

The duckbills (only one on each side of the discharge pump, two on each side of the vaccuum pump) on the intake side should be aimed in the same direction as the duckbill on the outlet side...iow, waste comes into the duckbill's wide opening and goes out through the the slit into the pump...out of the pump through the opening and through the slit into the hose. Worst thing that should have happened was the "bills" on the duckbills spread open too far to reseal.

[Clamdigger62]

Peggie you are partially right, the intake valves point into the pump and when there is a restriction in the discharge hose out side of the pump it will build pressure inside the pump that will flatten the intake duck bill valves and if left running the pressure will cause them to invert.
Certified Sea Land Super Tech

[peghall]

Originally Posted by Clamdigger62

Peggie you are partially right, the intake valves point into the pump and when there is a restriction in the discharge hose out side of the pump it will build pressure inside the pump that will flatten the intake duck bill valves and if left running the pressure will cause them to invert. Certified Sea Land Super Tech

Ok...that makes sense...finally.

(Former certified V/Flush distributor/dealer/tech...and owner)

[St. Elsewhere]

Originally Posted by Scott Berg

You MUST have a valve between the tank and any overboard pump or the shoreside pump out systems will either invert the duckbill's or pull the seals out of the Jabsco type pumps. Most manuals make this clear.

It's also a good idea to have a vacuum break on the holding tank in case of a clogged vent when using powerful shoreside pump-outs. Sealand sells a good one...

This may explain some issues on my system. I have experienced failed Sealand macerator duckbills that I thought was due to pumping with some speed on the boat, but maybe it is a high powered shore pump-out causing the issue. I have the larger Sealand vent filter and associated plumbing. I have not been aware of the Sealand vacuum breaker. Can you provide a part number? I found this one for the toilet bowel, but none for the waste tank.
Sealand Technology Vacuum Breaker Kit /910 911 2010 385316906