What's the difference between plastic pipes??

[Blackspaven]

Apologies if this is a regularly asked question, but I can't find it easily on the search.

What's the difference between all the different types of 15/22mm flexible plastic pipe used for the feed (NOT the rigid waste pipe)? The list below is cut & pasted from someone else who wasn't actually answered so can anyone clarify if they're used for specific plumbing jobs or what, just so I & others know what can be used for certain projects?
Also, are there any definite rules about using plastic pipe, even obvious ones such as using pipe inserts with compression fittings so they don't squash the pipe?

PE-X Barrier Pipe
BPEX Barrier Pipe
Polybutylene Pipe (WRAS approved)
Polybutylene Barrier Pipe
Plastic covered flexible copper

I get that copper is generally seen as 'better', but occasionally it's not simple to get a pipe where you want it so it'd be handy to know what to use and how in the absence of copper. Unfortunately, there's so many options available to buy, it's hard to know what to get, and generic Google searches seem to just give results on where to buy it, not how best to use it once you've got it!

Perhaps the mods can pin/sticky this thread so others have a resource for knowing what's what in the world of plastic pipe? Many thanks.

 

[Ray Stafford]

Some basic differences:

PEX (cross linked polyethylene) pipes tend to have memory - they want to spring back into the shape that they were on the roll. This can be very awkward, particularly when dealing with larger bores, or when attempting to lay a large run (for instance on underfloor heating). By far the most famous is John Guest Speedfit

PB (Polybutylene) pipes have less memory. They still have a tendency to coil, but not nearly so pronounced. The most famous is probably HeP20 and Polyplumb.

Either PEX or PB non-barrier pipe will allow some oxygen transfer from atmosphere to water. This is not really a problem on hot and cold supplies, but can be a real pain on closed circuits (like heating systems) as it promotes corrosion. The solution to this issue is to use barrier pipe, which is marginally more expensive to produce. Since the cost difference is so small, there is little reason to bother with non-barrier.

Plastic covered flexible copper is a completely different product for a different purpose. The plastic coating is designed to stop the copper being corroded when buried, run through concrete, plaster etc.

Returning to the plastic pipes, there are some useful general principles:

Always use inserts. Remember that John Guest have a different insert for compression fittings than for plastic fittings.
Try not to mix and match pipe and fittings. Although theoretically it should work, if you have problems, the manufacturers will blame each other.
Cut plastic pipe cleanly with a tool designed for the job, and definitely not with a hacksaw
Push the pipe properly home into the fitting
Pressure test before going live with WATER. Pressure testing with air is risky.

 

[Blackspaven]

Many thanks, good info.