Plugging the Vent Tube

[Randyonr3]

Been looking but cant seem to find what I'm looking for.. need assistance..
On the vent tube of the holding tank, looking for a type of a flapper valve that will allow vent without allowing solids to pass.. I have a filter above the tank to filter the nasty air comming out, but when the tank is full, it shoots up the vent tub and destories the filter..
and its uasally when the grand-kids come to visit.. not watching the tank level and it over-fills..............
any help finding a valve or a stop system for the tank.

[hlev00]

You should never fill your tank that far. And if you block it as you propose, the pressure might build up and cause the tank or something else in your system to rupture.

[hlev00]

P.S. Get all the grandkids to help replace the filter next time it happens. They'll be a lot more attentive to the tank monitor.

[denverd0n]

I have to agree that the solution is not some kind of valve as you propose. Perhaps a tank level monitoring system, that will sound an alarm when it gets about 3/4ths full?

[Terra Nova]

Originally Posted by hlev00

You should never fill your tank that far. And if you block it as you propose, the pressure might build up and cause the tank or something else in your system to rupture.

Originally Posted by denverd0n

I have to agree that the solution is not some kind of valve as you propose. Perhaps a tank level monitoring system, that will sound an alarm when it gets about 3/4ths full?

Hard to add anything to this. When you get tired of replacing filters you will become more attentive to emptying the tank on time.

[a64pilot]

There is a valve that is nothing more than a ping pong ball in a tube, when liquid floats the ball, it seals shut, it's very much like the valve in any wet or dry vac that shuts off air flow before the water gets pumped though the electric motor.
I know of the existence of these valves, but don't have a source, sorry

[thinwater]

A. Don't fill the tank.

B. Don't even consider a flapper; if you keep pumping the tank will blow.

Instead, use an overflow with the liquid filled trap, like under a sink. As you can see, the vent rises from the tank and either Tees to the filter or can over flow through the loop. Gases do not go out the trap because it is filled with water, like a P-trap.

Basic plumbing such as you would find in any house (every house has multiple roof sewer vents).



I've had this system for over 3 years. I did replace the clear hose with white sanitation hose (the clear hose not only permeates, it also kinks.

[Randyonr3]

Originally Posted by a64pilot

There is a valve that is nothing more than a ping pong ball in a tube, when liquid floats the ball, it seals shut, it's very much like the valve in any wet or dry vac that shuts off air flow before the water gets pumped though the electric motor.
I know of the existence of these valves, but don't have a source, sorry

good answer, and thanks, using the ping-pong ball, I can make the unit with a couple pieces of PVC and reducers.... the complete piece would be no longer/ taller than a couple inches..
Thanks again,

[Terra Nova]

That is not a good idea. The tank vent needs always to remain open.

[Dsanduril]

I'm with the rest of the team, you really don't want the chance to plug the vent. But, if you insist, and if you don't want to build your own, you're looking for an "air release valve":

Plastic Air Release Valves

[northoceanbeach]

It's considered bad form to use the head for anything other than liquid waste. This should solve your problem.

[Randyonr3]

Originally Posted by Dsanduril

I'm with the rest of the team, you really don't want the chance to plug the vent. But, if you insist, and if you don't want to build your own, you're looking for an "air release valve":

Plastic Air Release Valves

I knew someone would come up with the unit.........

Be it a good Idea or bad, its the choice I've made.. Been on the boat living aboard for 12 years now, been sailing for over 40, and on the very rare occasion will the tank be full enough that it would back up the vent tube.
I'm not that stupid people, I've rebuilt this boat from one end to the other and would go to say I've replaced every screw and pin on the boat.
Even if and I say If the vent was blocked off completly, the force would be directed through the Electro San and overboard throu the throu-hull.
at the present the vent is blocked off completely when the level reaches the filter, I'm just stopping the waste from getting to the filter..
And the system has been working fine for the last 10 years or so and does not need to be re-designed.. the piece is only there to protect the filter...

But thanks to all for trying to re-design my freggin boat for me.....

[Dsanduril]

We're not redesigning your boat, you are We're telling you to leave it alone

There are lots of different manufacturers of the valves out there, see if you can look at a cross-section (as the link posted has) and evaluate how hard it will be to clean out if the $h1t every gets up there. The simple floats are the easiest, avoid like a plague (in this service) and valves that have levers and linkages.