Size and number of duck bills

[tgebler]

I have a 2000 396 Aft cabin. This spring I want to replace the duck bills on the sanitation pumps. I know I have Sealand Vacuflush systems but I do not have a model number and I am not at the boat.

Apparently, it is either a S or T pump and it appears from my search that it will require either a 1 1/2" or 2" size duck bill. Also, it appears that one model requires 2 duck bills and the other 4 duck bills.

Is there a way of knowing which I have (S or T) and what is required without goinig to the boat. I looked through the documentation that came with the boat without luck.

Thanks.

[Viper]

They're likely 1-1/2" When looking at your pump, is there an inlet and outlet on the sides of the pump? Is the pump mounted on top of a tank or does it sit by itself?

[tgebler]

Unfortunately, I am not near the boat but additional research seems to indicate it is T series (#808 or #840) and requires 2 1 1/2" duck bills for each head. I am hoping someone can confirm. Thanks.

[Viper]

They will be 1-1/2" valves

[Viper]

By the way, are you sure that's the pump you have and not an S pump? The T pump is not a vacuum pump for generating a vacuum for the Vacuflush system. It is a waste discharge pump.

You likely have the S series pump and you would need 4 valves per pump. I'm guessing this is the one for your vintage unless changes were made. This is typically the pump used with a separate tank.

[tgebler]

ok, now you are giving me an education. Theree are two discharge pumps and two vacumn pumps then? So the duck bills are for the vacumn, i.e., the S series and I would need four duck bills for each of the vacumn pumps? I have a stack of books and phamplets that came with the boat and no mention of these different pumps.

Thanks so much for the lessons. This forum is without equal.

[Viper]

There would be one vacuum pump like an S series per toilet to build vacuum. These would also pump the waste into one or two waste tanks depending on the boat model. The T series pump is just a general bellows type pump that can be used for a number of applications like pumping the waste out of the waste tank. This is separate from the Vacuflush system, they are not needed for your Vacuflush system toilets to work. Both S and T pumps use duckbill valves. The S pump has 4 valves and the T pump has 2.

[tgebler]

Thanks again. Your responses are very helpful. I think I will buy 12 1 1/2" duck bill valves and change all of them this spring. I don't have any idea when they were last changed but not in the last 3 years.

We have two heads with seperate pumps for each; both vacumn and discharge, so a total of 4 pumps

[Viper]

As long as you're sure you don't have a J, B, or M series pump you're good. Those take the 2" valves. The J series pump for example has one of the ports on the bottom of the housing as this pump is designed for and mounted directly on to the top of a particular style vacuum generator tank. The bottom port goes right into the tank. This type of pump only has one port on the side of the pump housing.

[Midnightsun]

I always identified Vacuflush systems by the vacuum generator. VG 2 takes 1 1/2" duck bills and the VG 4 takes 2. duck bills. Older boats had the VG 2 system and the newer one have the VG 4 system. My 2007 has the VG 4 however I do not know what year they went to VG4. Regardless of the model they both require 4 duckbills for an overhaul. This link should identify your system visually. https://www.dahlberg-sa.com/wp-content/ ... arison.pdf