Holding tank pump-out

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Graham_Wright

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www.mastaclimba.com
My (Plastimo) "WASTE" deck connector has an internal thread which secures the cover plate and a chain to hold same.

The chain prevents a hose fitting being screwed in but can obviously be removed (probably self removing eventually).

Question is, how do pump-out facilities work? Does the hose connect and seal at deck level or is a hose passed into the tank? If a special (perhaps bayonet) connector is required, what does "WASTE" mean on the Plastimo fitting?
 
All the pumpouts I used in the world had really bad rubber nozzles that are meant to seal to the deck opening. The problem is they all get chewed up by the threads.

There is a coupling that couples the nozzle to the control valve. You can release this and couple it directly to a screw in adapter. The only problem is that you have about 1' of valve and coupling with a great big hose supported on the tread. Once you start the pump (slow diaphragm pumps) the water in the line can start oscillating. Another way is to insert the rubber nozzle into the smooth adapter hole.

http://www.westmarine.com/webapp/wcs/stores/servlet/product/10001/-1/10001/256383/10001/71/70/11

PS I only ever found 1 pump out facility that worked first time in California. However there was a company barge called "Empty heads" that did it for you. The main reason was the old holding tank was 3' under the water level and they did not have the suction head ability to raise the water to deck level.

Look at the lower left of this picture:

http://www.westmarine.com/webapp/wcs/sto...hallpartial/0/0

(There is no way any of it works with a chain, Sorry)
 
how come nobody knows how to use pump outs ? oh I know we all go 3 miles out to sea and press the macerator dont we !
 
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My (Plastimo) "WASTE" deck connector has an internal thread which secures the cover plate and a chain to hold same.

The chain prevents a hose fitting being screwed in but can obviously be removed (probably self removing eventually).

Question is, how do pump-out facilities work? Does the hose connect and seal at deck level or is a hose passed into the tank? If a special (perhaps bayonet) connector is required, what does "WASTE" mean on the Plastimo fitting?

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First, get rid of the chain. Water and fuel fills can have chains, because it's not necessary to seal the fitting to fill water and fuel tanks...but waste fittings should not have one because NO pumpout nozzle--threaded OR hard rubber--will seal as long as it's there. And then either be very careful to set the cap down where it won't fall overboard when you remove it, or be prepared to replace it often.

Pumpouts connect to the deck fitting...then pull waste up the discharge hose from the tank to empty it...the pumpout doesn't not go into the tank.

"Waste" is stamped on the deck fitting because it's the fitting to empty the waste tank. If you look at your water and fuel fill fittings, you should see 'water' stamped on the flange of the one through which you fill your water tank and either "fuel" or "diesel" stamped on the flange of your fuel fill fitting.

It's important that you pay attention to what's stamped on each fitting...helps to avoid the embarrassing--and sometimes costly!--mistakes of pumping out your fuel tank or filling your water or waste tank with diesel.
 
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First, get rid of the chain. Water and fuel fills can have chains, because it's not necessary to seal the fitting to fill water and fuel tanks...but waste fittings should not have one because NO pumpout nozzle--threaded OR hard rubber--will seal as long as it's there. And then either be very careful to set the cap down where it won't fall overboard when you remove it, or be prepared to replace it often.

<span style="color:red"> The chain is easy to lose but could be left connected to the cover and detached from the fitting I guess; extra long and left in the lift pipe, it might be easier to keep on board. But then, it's going to get awful pongy after a few pump-outs.</span>

Pumpouts connect to the deck fitting...then pull waste up the discharge hose from the tank to empty it...the pumpout doesn't not go into the tank.

<span style="color:red"> Yes, "connect" but how. That was the point of the original question. What thread is "threaded"? Is it universal? Knowing the Brits, the French and the Americans, they'll all opt for different choices unless agreed by some mechanism. If the hose is "hard rubber", what diameter? Again is this an international standard?</span>

"Waste" is stamped on the deck fitting because it's the fitting to empty the waste tank. If you look at your water and fuel fill fittings, you should see 'water' stamped on the flange of the one through which you fill your water tank and either "fuel" or "diesel" stamped on the flange of your fuel fill fitting.

<span style="color:red">Er, thanks Peggy! I did actually work that one out! However, in my case the water fill has to be sealed to prevent the ingress of air. With the arrangement I have installed (with the agreement from Plastimo whose flexi tanks I have fitted) the fill and draw are shared.</span>

It's important that you pay attention to what's stamped on each fitting...helps to avoid the embarrassing--and sometimes costly!--mistakes of pumping out your fuel tank or filling your water or waste tank with diesel.

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<span style="color:red">Just a rider seeing as I have the attention of the expert, what diameter breather do you recommend for the holding tank? I understand the necessity for bacteria sustenance and to avoid collapsing the tank when sucking out but the recommended 38mm seems a bit over the top?

Thanks very much for your continued and expert advice on behalf of all the forumites;- keep it up!</span>
 
You asked, " Yes, "connect" but how. That was the point of the original question. What thread is "threaded"? Is it universal?"

Yes...there's an ISO standard that should make all pumpout fittings threaded the same, in one of only two diameters.

"If the hose is "hard rubber", what diameter? Again is this an international standard?"

Not the hose, but a fitting that attaches to the dockside pumpout using a cam coupler...and it's tapered to fit any size deck fitting. You just jam it into the fitting and hold it tightly while the tank is pumped out.

You've confused me with this one: "However, in my case the water fill has to be sealed to prevent the ingress of air. With the arrangement I have installed (with the agreement from Plastimo whose flexi tanks I have fitted) the fill and draw are shared."

I don't understand how that would work. The water tank is filled from the deck...water is drawn out by a pump below decks.

Btw...your waste tank IS vented...it's not an unvented bladder, is it? Unvented bladders cannot be used for waste holding.

The so-called "standard" vent line size for a holding tank is the same as fuel and water tank vents--5/8". But that was decided without any thought to the idea that fuel and water don't require any management, just storage...and rarely become clogged, whereas waste must be managed and tank vents often do become clogged if neglected--even larger diameter. So a larger diameter is really needed for a waste tank for two reasons: 1. doesn't clog as easily...and 2. to provide the oxygen needed to keep the tank aerobic, which is the key to eliminating odor. For more information about that, see the article on the Tek-Tanks site here: http://www.tek-tanks.com/sanitation/sanitation_index.html


So no...38mm or even larger is NOT over the top. But even a large diameter vent is not immune from becoming blocked, so regularly inspection and backflushing to clear it are essential if you don't want a pressurized tank (ever see an eruption when the pumpout cap is opened? That's due to continued use of the toilet against a blocked tank vent) or an imploded tank.
 
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You've confused me with this one: "However, in my case the water fill has to be sealed to prevent the ingress of air. With the arrangement I have installed (with the agreement from Plastimo whose flexi tanks I have fitted) the fill and draw are shared."

I don't understand how that would work. The water tank is filled from the deck...water is drawn out by a pump below decks.

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Please excuse this digression. The fresh water tanks are flexible so do not need to be vented. As long as there are no air leaks, sucking on the fill pipe will draw water from the tanks (and Plastimo, the suppliers, agree <u>as long as the fill point is air-tight.</u>
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Btw...your waste tank IS vented...it's not an unvented bladder, is it? Unvented bladders cannot be used for waste holding.

Yes, it is a rigid stainless steel tank. I wondered if the difference in viscosity between holding tank contents and air might permit a smaller diameter air intake. Lee Sanitation had advised 38mm but I welcome your endorsement

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Thanks for your help Peggy;- your word is Gospel!
 
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