I want to use metal compression fittings rather than the standard push-fit MDPE couplings on 20mm (I/D) blue MDPE pipe.
Can I use what is described as standard 22mm compression fittings where 22mm presumably is the O/D?
Incidentally, I have a brass stopcock for use with 20mm ploy pipe and it has 20 cast into the side of it -suggesting that 20mm MDPE might require a special type of compression fitting.
Can someone help clarify please?
MDPE couplings on 20mm (I/D) blue MDPE pipe.
presumably is the O/D?
20 cast into the side of it -suggesting that 20mm MDPE might require a special type of compression fitting.You'd need to replace the olives with these:
-fit MDPE couplings on 20mm (I/D) blue MDPE pipe.
2mm presumably is the O/D?has 20 cast into the side of it -suggesting that 20mm MDPE might require a = special type of compression fitting.
Pipe sizes are peculiar. 22mm is the nominal bore size. But the bore size depends on the thickness of the wall. All 22mm pipe are the same OD but different bores depending on the pressure rating of the pipe.
On many plastic pipes, if you are using a compression fitting, you need a stiffer plastic/metal insert goes inside the pipe to stop it "collapsing". ie so you get the proper "pinch" effect as you tighten the nut. A few are non standard so you can't use a compression fitting, you will need to check.
BTW there are several different sorts of plastic fittings for the blue MDPE pipe from different manufacturers. But I know what you mean, they all seem a bit dodgy. Most have O rings that can be damaged as you assemble the fitting round the pipe.
In article , harry writes
What a confusing and contradictory statement.
Metric sized copper and MDPE are not in any way peculiar, their quoted size is the external diameter of the pipe ie. the size of the fitting or olive required to mate with them.
Andrew has kindly pointed to required olive.
That much is true.
You only think that because you only see/know about pipe used in domestic houses. This is only a small part of what's available. There is a whole other range of pipes used in industry for chemicals, steam, higher pressures, underground, annealed, hard drawn. etc.
Clearly stuff you know nothing about.
And what do you think his enquiry is about?
There's no need to confuse him or bore him with unnecessary detail.
The main issue was your contradictory and confusing statements, "22mm is the nominal bore size" and "All 22mm pipe are the same OD", clearly those 2 statements are mutually exclusive.
Why is that? Don't you understand the difference between bore and OD?
The OD is always the same so that the pipe fittings always fit. The actual bore varies depending on the wall thickness/pressure rating of the pipe.
The pipe fittings are higher pressure for ease of manufacture and fit a range of pipes.
I'm afraid I misread your post, it wasn't contradictory, it was simply wrong:
22mm is not the "nominal bore size" of the pipe as you stated, it is the outside diameter.The o/p will be using 20mm o/d MDPE pipe in a compression fitting designed for 22mm o/d copper pipe and will need to use the 20-22mm olive previously referred to by Andrew.
Let's hope that clears things up.
You really are a f***g half wit rambling on about topics you have zero knowledge about.
In article , snipped-for-privacy@gmail.com writes
Apologies for various bits of misinformation and confusion in this thread, I think both myself and Andrew failed to notice that you said
20mm _I/D_ as the size for your pipe rather than _O/D_ (outside diameter) which is the dimension that current domestic MDPE pipe is sold and specified in.If your pipe really is MDPE (is it blue?[1]) and has an I/D of 20mm then it is actually 25mm MDPE pipe. This will not fit a 22mm compression fitting as it is sized for the outside diameter of the pipe it is to mate with ie either 22mm (_O/D_) copper or internal plastic plumbing pipe, and sadly 25 into 22 will not go.
The conversion olive that Andrew pointed to was for adapting 20mm MDPE pipe (_O/D_) to a 22mm brass compression fitting so that will not work on the 25mm MDPE pipe that you have.
I note that the same outfit also sell a conversion olive for 25mm MDPE:
This means you need a 28mm compression fitting. If you then want to mate
22mm copper to this then you will need a 22mm 'reducing set':In article , harry writes
I think my latest reply, direct to the o/p will clarify.
He appears to actually have 25mm MDPE which (in answer to his question) will not fit a 22mm compression fitting but I have offered an alternative solution.
And finally, just to clarify, can you perhaps explain what you meant by "22mm is the nominal bore size." in your original reply, it doesn't appear to relate to either 22mm domestic copper or 25mm domestic MDPE metric pipe sizes. Just a sentence will do, own words preferred, no need for links thanks.
Of course not. That's what nominal means. The pipe commonly available for domestic applications is just a small part of a much larger range. Read the link.
The clarification I am looking for is how a pipe with a bore of 22mm can also have an o/d of 22mm as you seem to imply?
Bores are nominal. ODs are exact. Didn't you read the link?
Care to quote an authoritative reference that describes 22mm o/d copper tube as having a 22mm nominal bore?
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