Good diagram and description of operation of a torbeck diaphragm valve anyone?

[Clive]

Hi,

A friend of mine has a toilet with closely coupled system and
overflow empties into the pan. After a fair amount of googling I think
she has a bottom-supply torbeck type valve. We have carefully taken
the thing apart and checked the diaphragm for tears or build up of
crud. I have put it back together in the same order is I dismantled it
and didn't cross threads etc. All I have succeeded in achieving is the
valve does not shut the supply off at all when the float is up and the
cistern overflows at a much higher rate. At least we understand (sort
of) the problem - but for now the toilet is out of action - I have
shut off the supply to that toilet.

Now I have seen many wordy description of how these should work but
does anyone know of a link to a site that shows exactly the operation
and the areas where the valve can fail? The only part that seems
relevant to creating the seal to shut off the supply is the diaphragm
valve with a tiny, delicate pin type thing that passes through the
middle of the diaphragm. The following seems a pretty good image of
the diaphragm

https://www.choiceful.com/choiceful-id-5999-Armitage-Shanks-Diaphragm-Washer.html

but I'm not sure it is the correct one. The valve mechanism has no
manufacturer stamp - just "Quiet Ball Valve" moulded into it.

Could the problem be something to do with the tiny pin hole in the top
of the valve body?

Can anyone provide any more info on the operation of these or advice
on replacing diaphragms or replacing the whole unit?

Thanks

Clive

[The Medway Handyman]

Post by Clive
Hi,
A friend of mine has a toilet with closely coupled system and
overflow empties into the pan. After a fair amount of googling I think
she has a bottom-supply torbeck type valve.

Just replace it. What do they cost £10 - £15?

Not worth trying to repair it. Remove the old one, take it to a proper
plumbing shop & get a direct replacement.

[Clive]

Just replace it.  What do they cost £10 - £15?
Not worth trying to repair it.  Remove the old one, take it to a proper
plumbing shop & get a direct replacement.
--
Dave - The Medway Handymanwww.medwayhandyman.co.uk

My view is that replacing a washer / diaphragm wastes less material
and is a whole lot less disruptive than replacing the whole device.
that of course assumes it was the diaphragm that caused the problem.

Unfortunately my purist bubble was burst in that I couldn't get a
replacement diaphragm.

We bought a replacement Torbeck, fitted it - and even when the float
was up the flow wasn't stopped or restricted one bit.

So off came the Torbeck and an order for a FluidMaster was placed. The
Fluidmaster seems a more robust bit of kit.

The FM is installed and works fine in that the water flows into the
cistern and cuts off totally when the float is raised. Also the water
filling from the base of the device is almost silent.

Two problems

I fitted the flow restrictor and the filling is very slow - so I will
have to take that out. I don't know if the cistern supply is tank-fed
or direct mains.

I put PTFE tape around the brass pipe at the bottom of the FM and
replaced the washer in the flexible hose. The washer looks like it is
made of fibre rather than rubber. I carefully cleaned the place where
the washer was to be seated. I carefully tightened everything to
ensure no threads were crossed and I didn't over tighten - barely a
quarter turn with a spanner after hand-tightening. There is a *very*
slow leak from the "bottom" of the hose nut - as if the water is
somehow coming "around" the new washer. I'm hoping that the leak will
seal as the water here is hard. Any ideas of some step I missed in
assembling and fitting the FM tha might mean the leak will remain? I
will probably have to dismantle anyway to remove the flow restrictor.

Clive

[Sjan]

replying to Clive, Sjan wrote:
I think your problem is with the small pin. My hypothesis is the pin allows
the water to enter the space behind the diaphragm and build up pressure there.
This leak has to be very small, otherwise water leaks constantly outside
through the thread.

--
for full context, visit https://www.homeownershub.com/uk-diy/good-diagram-and-description-of-operation-of-a-torbeck-diaph-535824-.htm