How does a marine toilet work?

[tudorsailor]

I have a Raritan PH Superflush manual toilet. I wonder how it works. It has a pumpy handle and two settings, "flush" and "dry". I do understand that when turned to "flush" that water is pumped in to the bowl. However, I cannot find a plan to show how the pump, pumps waste out of the toilet while pumping water into the bowl.

Thanks

TudorSailor

 

[pvb]

All these manual toilets work in essentially the same way. The pump chamber has a piston, with sea water above it and waste water below it. When you pull the handle up, waste water is drawn into the lower part of the pump and sea water is pumped out into the bowl. Then, when you push the handle down, the waste water is expelled into the discharge pipe, and more sea water is sucked in to the upper part of the pump. The flush/dry lever controls a little valve which stops sea water being sucked in to the pump.

 

[knuterikt]

The pump is a piston pump, it uses one side of the piston to empty the bowl the other side is used to pump sea water.
In dry possition the valve on the flush side is blocked in open position

Edit:
pvb typed faster than me....

 

[dom]

Try this link: https://youtu.be/BnQq4d-NmkE

 

[maby]

My only observation on the above is that they seem to be designed so that the volume of water pumped in on each stroke is rather more than the volume pumped out - otherwise you would not be able to fill the bowl with clean water.

 

[tudorsailor]

Try this link: https://youtu.be/BnQq4d-NmkE

Perfect! Many thanks

Will now get armed with equipment to see why "the waste goes out" but not much water comes in! I think I need a new O ring on the piston.

TudorSailor

 

[savageseadog]

A better and a more interesting question would be " How Does a Marine Toilet Not Work?"

 

[knuterikt]

Perfect! Many thanks

Will now get armed with equipment to see why "the waste goes out" but not much water comes in! I think I need a new O ring on the piston.

TudorSailor

could also be the valve on the inlet side, once I had the "coin" fall off the flap valve...

 

[JumbleDuck]

My only observation on the above is that they seem to be designed so that the volume of water pumped in on each stroke is rather more than the volume pumped out - otherwise you would not be able to fill the bowl with clean water.

Actually, the amount pumped out should be more than is pumped in, or flushing would not work. All the designs I have seen do this, sort of, by having the clean water side next to the handle; since the piston is on that side the swept volume is less by the full volume of the piston. It's not much, though.

I have a Raritan PH Superflush manual toilet. I wonder how it works. It has a pumpy handle and two settings, "flush" and "dry". I do understand that when turned to "flush" that water is pumped in to the bowl. However, I cannot find a plan to show how the pump, pumps waste out of the toilet while pumping water into the bowl.

It's a while since I overhauled a Raritan (Compact, in my case), but from memory the "flush/dry" control rotates a small valve in the inlet, blocking off the flow of water. It's a rotten design, because the pressure differential which results gives you blowback past the piston and the inlet side gets contaminated. If yours is giving the slightest trouble I would recommend ditching it. A better replacement is a hundred quid or so.

 

[maby]

Actually, the amount pumped out should be more than is pumped in, or flushing would not work. All the designs I have seen do this, sort of, by having the clean water side next to the handle; since the piston is on that side the swept volume is less by the full volume of the piston. It's not much, though.
...

.

Not on a Jabsco, at least - if you set it to flush and keep pumping it will slowly fill up. You have to set it to drain in order empty it.

 

[Gwylan]

I have a Raritan PH Superflush manual toilet. I wonder how it works. It has a pumpy handle and two settings, "flush" and "dry". I do understand that when turned to "flush" that water is pumped in to the bowl. However, I cannot find a plan to show how the pump, pumps waste out of the toilet while pumping water into the bowl.

Thanks

TudorSailor

Is it working?

Answer - yes!
Stop worrying.

Generally only put what you have eaten down there and ensure any contravention results in keel hauling.

It is amazingly ingenious and requires bits of rubber that flip and flop and other bits.
I repeart, is it working, leave it alone and get on with sailing.

 

[VicS]

Not on a Jabsco, at least - if you set it to flush and keep pumping it will slowly fill up. You have to set it to drain in order empty it.

JD is right about the relative volumes of the two pump chambers but in practise probably what happens is that a little more water than a " pump full" syphons in during each stroke and/ or a little less that a " pump full" is ejected on the downward stroke esp if the bottom valve gasket is not seating properly or the joker valve is not closing as well as it might.

 

[TQA]

Any way leave it on flush all the time except when you might want to pump the bowl dry. I do this about one a month to fill the bowl with litre of white vinegar and let stand overnight.

If it starts to squeak a few drops of cooking oil in the bowl will fix that on the next use.

I have the earlier PH 11 and they externals may well be 38 years old. I always carry a rebuild kit and an extra joker valve. It is worth knowing that the Jabsco and Greco joker valves both fit, in fact some magazine tested them all and found the Jabsco to be the best. Something to do with the three sided design.

 

[maby]

JD is right about the relative volumes of the two pump chambers but in practise probably what happens is that a little more water than a " pump full" syphons in during each stroke and/ or a little less that a " pump full" is ejected on the downward stroke esp if the bottom valve gasket is not seating properly or the joker valve is not closing as well as it might.

Ours has always filled up on flush since the day the boat was delivered from the factory. Think about it - you need to be able to fill the bowl to clean it properly and the switch only inhibits the incoming stroke, not the exhaust stroke - it makes much more sense to design it to pump more in than out.

 

[ghostlymoron]

I can't see how the swept volume of inlet and outlet sides can be different. There is only one plunger and it moves through the same distance. There may be slight difference in volume when propelling solids through the pump. Generally they work well but it's worth carrying a service kit on board and not overtightened the screws. I've not experienced problems with putting soft toilet paper down it (in moderation) but some people do.

 

[Daydream believer]

If it starts to squeak a few drops of cooking oil in the bowl will fix that on the next use.
.

If I slipped some in the mother in law's food would it stop her b..y squeaking

 

[pvb]

I can't see how the swept volume of inlet and outlet sides can be different. There is only one plunger and it moves through the same distance.

That's right.

 

[duncan99210]

No idea but an experiment is called for I think.... Perhaps using caster oil?

 

[TQA]

I can't see how the swept volume of inlet and outlet sides can be different. There is only one plunger and it moves through the same distance. do.

One side has the pump rod attached. The volume of the pump rod is the difference. If you have a problem visualizing this make the pump rod much thicker. The swept volume will be less on the rod side.

 

[pvb]

One side has the pump rod attached. The volume of the pump rod is the difference. If you have a problem visualizing this make the pump rod much thicker. The swept volume will be less on the rod side.

That's right too. But, this means the volume of flushing water is less than the volume of waste water removed. This rather contradicts others' observations.