stopcock "arrow" indicator

ISTR being told that if a stopcock is fitted with the flow reversed then the water pressure might push the jumper into the seating and so stop water flowing. That may have been from the same school as the instruction to fetch a left-handed mug and a dozen round tuits but it was also explained as being in the nature of a sort of isolating valve to limit flow back into the "mains".

Arrow should be in the direction of the flow / supply.

Mr Pounder

yes, to indicate the direction it must be fitted in.

Yes, and as with all "just taps", they are asymetrical, they must be fitted in the direction of the flow. Look inside the tap. You will see that the inner pipework goes from the "in" end, bends through

--+-- | +|-----, ||+---, \ |+| \ \ / \ \ \

---+ | \ '---

-----+ ---> '----

Like this:

JGH

Even better diagram here:

Hum. I've never thought about it before. So, I guess I need a bi-directional full-bore service valve. Simon.

If it's for isolation (or low pressure, eg, from storage tank), yes. A gate valve would also do (that's one where a gate descends across the flow of water to stop it - peer down the pipe as you operate it to see what happens).

If it's a supply feed, no, you need a stop tap.

JGH

It is to isolate some pipework that may be used at some point in the future (to avoid a long dead leg of stagnant water). Also, if I get a new water supply to the house, this section of pipe will have the water flowing the other way. It needs to shut off the water completely, which a gate valve does not do.

By "supply feed" do you mean the main isolation for the water supply to the house ? Yes, a stopcock is required for this of course.

I'll get something like this:

Thanks, Simon.

No. The ball can be lifted off its polymer seat by the water pressure if fitted backwards. Though there is a seat the other side, it's not as "fixed" being held in by a retaining clip.

A house I recently worked on had the kitchen floor ruined by a weeping service valve which had been fitted backwards.

So is there any reversible valve that I can use ?

Simon.

Probably a gate valve.

In message , sm_jamieson writes

As long as it's accessible enough swopping it round in the future wouldn't be that hard.

Does not seal off completely in my experience, Simon.

Yeh, although half the point of the exercise was to avoid that. How about 2 ball valves back to back ? As long as the one that the water reaches first is used to switch off you would be OK. Oh, and make sure the other valve is fully on all the time. Hopefully the small restriction caused by the open valve would not be enough to mess with the seal. Simon.

Or two, back-to-back.

TapRays!

Wots the saying - grate minds think alight ? And a big sign saying "to any operators of these valves, here are the vital instruc ... (big bit of burnt wood where some soldering has obviously occurred) Simon.

In message , chris French writes

What about just clamping the pipe?

Technique 1..... fold end of pipe back on itself and secure with cable tie. 2.... weld end closed with blow lamp or cigarette lighter etc.

regards

Last year I had to ask on here as the full-bore valve didn't have an arrow. If there is a correct way, it should be indicated; no indication implies that it doesn't matter but sometimes it does.