Blackwater Valve

[dale farley]

I have noticed when I pull the handle on the slide valve to dump my blackwater tank it seems to function a little strange. When I pull the valve all the way out, it flows for a few seconds then seems to almost stop. I can push the valve back in about 3/4 of the way, and the flow begins again. At this point the valve is only 1/4 open.

As part of a routine maintenance, the previous owner had both valves replaced in February of this year by Marathon in Texas. Since I have never had one of these valves apart, I don't really know how they look inside. I assume it is just a flat blade that moves out of the way and allows the flow. I don't understand why the flow would decrease when I pull the handle all the way out?

Can someone shed some light on how this might be happening? It's not really causing a problem, but I would like to understand what is going on.

[Jerry Winchester]

Dale,

Sounds like you have a Krakman sized Anaconda wedged in your tank that needs extraction.

Just flush these down the tank and you'll be in good shape. Remember to have the valve open.....

trick_balls_P.gif

[dale farley]

Jerry, I can't believe how fast I got the solution to my problem. Since I don't have any of these, how about bringing some of the Trick Balls to Spearfish? I am sure this is probably the solution, but I don't think I fully understand the theory behind it.

[Jerry Winchester]

Dale,

Unfortunately, or luckily if you are the Krakman, I won't be in Spearfish, but I am sure the ACME truck has already been there and will be making another stop prior to the rally.

[truk4u]

Dale,

I'll have the Acme Balls with me in Spearfish!

It almost sounds like a vent problem. On my grey water, it flows real fast for a few minutes and them almost stops until it vents (you can hear the woosh) and then empties. My black water full flows without any stop until empty.

[Jon Wehrenberg]

If it is a venting problem there will be a distinct oil canning sound as the tank goes to a negative pressure and then returns to atmospheric pressure.

It sounds like there is some blockage and moving the valve reorients the blockage.

May I assume the practice has been to let the tank(s) fill before dumping so the pile of poop is pushed out with the water flow? Some folks who stay in one spot for an extended time period leave their valves open and the net result is a serious accumulation of solids that accumulate over time and can create future dumping issues.

[0533]

I have noticed when I pull the handle on the slide valve to dump my blackwater tank it seems to function a little strange. When I pull the valve all the way out, it flows for a few seconds then seems to almost stop. I can push the valve back in about 3/4 of the way, and the flow begins again. At this point the valve is only 1/4 open.

As part of a routine maintenance, the previous owner had both valves replaced in February of this year by Marathon in Texas. Since I have never had one of these valves apart, I don't really know how they look inside. I assume it is just a flat blade that moves out of the way and allows the flow. I don't understand why the flow would decrease when I pull the handle all the way out?

Can someone shed some light on how this might be happening? It's not really causing a problem, but I would like to understand what is going on.

I have had a similar problem and I assumed is is some type of air lock that occurs. If I shut the valve and reopen it flows properly again.

Pam thinks its a build up of Gas, I'm not buying that one, but we do eat lots of tacos.

[JIM KELLER]

Dale, Getting this Thread back on track, I have noticed the same thing you posted at the beginning. I have always thought it was toilet paper jamming up at the discharge bend. I wonder if Septic Tank approved paper is better to use. I have also seen Buses at different repair facilities with the same issue. They call it " A Clog " and the new guys always get stuck with the job.

[dale farley]

Jim, The one thing I don't understand is that if it is really a clog, why would it drain fine as soon as I push the valve back in to about 1/4 open. That would seem to be reverse logic. You would think if it is clogged when open all the way, it would surely be clogged when only open 1/4 the way.

There surely must be a logical explanation to this if it is happening to others. It has never been a problem, just a mystery. I am considering the disassmbly of my valve just to see how it works. I am surprised that someone hasn't taken one apart and has a picture of it.

[Jon Wehrenberg]

Whatever you do, do not, I repeat, do not get down there and look up that pipe to see why it drains slow.