Plastic pipe connectors.

[Roger Hayter]

I need to replace our main incoming water pipe, presumably with whichever is the larger standard size of plastic tube. At the water board end, a plastic push fit connecter is screwed on to their brass stop tap and regulator. AIUI you can use ordinary copper tube type compression fittings on this plastic tube, or you can do as the water board does and connect a plastic push fit connector to the new brass inside stop valve I shall have to get. One of the pipes in the house will be the smaller variety of plastic tube, so with two push fit connectors the whole arrangement will be about a foot and a half long and take up a lot of space. Is using ordinary brass compression fittings just as good? Which are more likely to come undone with bending forces on the pipe or the tap? And, while I think of it, is it best to use special olives or the ordinary brass/copper ones?

Many thanks for any advice.

[Tim Watts]

I found it a bit hard to follow what you are doing exactly - but I do know that BES sell a brass MDPE termimal that is used with a platic pipe insert and it is relatively slim - comes with its own special olive for MDPE pipe.

[Roger Hayter]

That sounds interesting. Do you know if it is reliable. All I am doing is connecting a 28mm plastic pipe to a stop tap, and a 22mm plastic pipe to a short 22mm copper tube on the other side of the stop tap.

[Tim Watts]

More reliable than any form of pushfit -

The connector is solid brass and the olive bites into the surface (deforms) the MDPE so there is no way that is coming off.

I trust it to form the final connection to my incoming stopcock (22mm

1/4 fullbore ball valve) inside the house.

The only annoyance is, it has a 22mm heavy brass tail on the end which must be soldered to whatever fitting you really want before fitting to the plastic - as the brass tail is too rigid to deform at all, you cannot use a compression joint on it. Not too much of a problem provided you do this before fitting. IIRC I soldered a coupler to a short bit of

22mm pipe and then put the compression ball valve on that.

The "pushfit" (more of a "lock nut and big doughnut washers") adaptor I used outside to mate the MDPE to the 1/2" alkathene pipe is in an inspection pit as I trust it less, so wanted the means to check it occasionally. It however has been reliable to 7.5 bar as as the brass jobbie.

[Tim Watts]

But remember to buy the pipe inserts - black things about 1-1.5" long.

[Roger Hayter]

This is were I appear to be woefully confused. It seems I want 25mm MDPE for the mains side, but the ordinary inside piping is more likely

22mm OD plastic of some sort. Am I getting nearer what is required now?

[Tim Watts]

On 25/05/15 22:26, Roger Hayter wrote: y

Parts 11328-30 (Take your pick - mine was 11330).

Seems like the insert is included -

Does that help?

[Tim Watts]

And fitted:

[Roger Hayter]

Very helpful, thanks. Do you know anything about the inside plastic pipe? Can I use ordinary compression fittings, with inserts of course?

[Tim Watts]

Not sure Roger.

I'd go through to a stub of copper then use the appropriate connector for that. If it happened to be JG Speedfit internally then that's easy as the connector will mate with copper and JGS equally well.

[Roger Hayter]

Apparently as part of the same series they do a stop tap MDPE to 22mm. I wonder about the advantages of the full bore one you mention, do you reckon it is more convenient as well as better flow? Do you have a reference for it? I like the pressure valve. I've got one, but much further from the incoming main.

I don't know if a direct compression fitting on the rigid brass tail would be ok, especially with a copper olive. Presumably you were concerned it would slide off under pressure?

[Roger Hayter]

Yes that makes sense, I am inclined to do the same, gives something firm to fix the tap to.

[harryagain]

You can use compression fittings on plastic pipe so long as you can find ones the right size. You must fit a little bit of copper pipe inside the plastic (the "insert") to stop it collapsing as the nut is tightened.

[Tim Watts]

I like the fact that lever valves are clearly "on" or "off" visually. Also the full-bore does no harm.

It is just a Pegler full bore 22mm lever valve - either SF or TS sell them (as well as BES). Never had any trouble with Pegler and I have a lot of their lever and butterfly valves.

Mine is now - that stack you see terminates into 15mm Speedfit. It is now routed through the roof space in 22mm copper and the pressure valve is at a more convenient location in the lobby walk in cupboard (where a lot of pipework converges) along with a secondary isolator.

I *know* it will fall off.

I naively tried - luckily on the bench. Did it up tight and it was solid. Dropped the assembly on the floor my mistake, picked it up and the compression joint just slid off!

Reverted to soldering...

[Tim Watts]

Indeed - I would put a munsen or a hospital pipe clip either side of the tap too - then the bit that gets turned is rock solid.

[Cursitor Doom]

Or better still, avoid push-fit like the plague.

[Roger Hayter]

We're talking about 25mm compression - inserts even more vital. I suppose I could use steel pipe for the main, but it would upset the water board people unless I cut a thread on it for them to fit a pushfit connector!. And it's probably illegal.

[Tim Watts]

This is not push fit - it's compression - which is why the pipe inserts are particularly important!

[Tim Watts]

And MDPE will probably outlive the buried steel unless you are in the habit of trying to dig through it :)