In article , Nightjar
writes
On 17/01/2013 20:42, Dave Liquorice wrote:
On Thu, 17 Jan 2013 17:09:33 +0000, Nightjar wrote:

A length of steel pipe, larger ID than the OD of the drain, with a
flange on the bottom and a flexible seal on the flange? The weight of
the pipe should hold it in place while the water simply rises inside
it.

Might depends how much higher up the water is getting into the drains.
Remeber that hefty great cast iron road strength manhole covers can be
tossed aside by flooded drains...

Which is why I was thinking of an open topped pipe, rather than trying
to seal the drain. I take your point about how much higher the water is
getting into the drains, but in my house the foul water drain is
connected to an open gulley outside the kitchen, so it wouldn't rise in
the pipe any higher than the water outside.

Yes, that works when there's an equalised static pressure and the water
has found its own level. Consider also the state where moving water has
found its way into the drains and is under high dynamic pressure that
would find it jetting above the level of the pipe and potentially
disrupting the fit and seal.

To cope with those situations, I'd be looking at reverse flow prevention
devices _plus_ the precautions you advise.
--
fred
it's a ba-na-na . . . .