MDPE compression question

[nothanks]

The garden taps are plumbed in below-ground MDPE and connected to the water main via a Floplast stopcock, which is at the bottom of a small vertical access chamber. Something was leaking so I've dug-out the area around the stopcock and think the problem is down to metric-imperial mismatch, but I don't know enough about MDPE to know what I need. The input of the stopcock is 17mm OD black (I assume that's 3/8" imperial) and is not leaking. The output is 20mm OD blue pipe, which fits loosely into a plastic retaining ring and O ring that fit into the output side of the stopcock. The ring and O ring are about 21.2mm ID so I assume are for 1/2", and that this is the problem. I think I need replacement retainer and O rings for 20mm, but I can't find them. What do I need?

[John Rumm]

You could always get a transition fitting - they are designed to go between odd and irregular pipe sizes and types. BES have a good range of such things.

[nothanks]

I was hoping to find a metric lock ring to fit into the stopcock and replace the imperial one (no luck so far). The problem with a female-female transition is that I don't have any imperial pipe to run from the stopcock to the adapter. I suppose I need a transition coupling with a 1/2" male spigot on one side, but they all seem to be BSP threaded, rather than plain.

[Roger Hayter]

BES, as someone just said do a 20mm or 25mm pushfit plastic tube to plain 15mm or 22mm brass spigot (siuitable for a compression fitting, but you need supports to stop it coming out axially as the olive won't dent it much) adaptor.