Can metric be used instead of inch?

rony · Dec 1, 2017

Hi
I am about to buy a stock of adapter for water purifier (faucet divertor. please see attached picture), some chinese factories only work with metric system and I wonder if I can use them. my questions are:
1. Some answers I got is that the most common tap would be 55/64(at the connection point to an aerator). Do you agree that this would be the most widely used?
2. Since it is 22mm metric vs. 21.83mm (55/64inch x 25.4mm), and since factories that work with the US make only metric, can I assume that 22mm is also used in the US (no damage and no leaking?).
Thank You

Chuck · Dec 2, 2017

Metric and imperial threads are not compatible even if they appear to be similar sizes.

SimonG · Dec 2, 2017

Sounds like you are from the US?

Might get a better response from a US forum?

Ric2013 · Dec 2, 2017

You may get a better answer if you post your question on a US site. This is UK plumbers forums, and I'm assuming your question relates to a US tap?

EDIT Sorry Simon, posts crossed!

rony · Dec 3, 2017

Thanks Guys.
Yes I noticed the site name */co.uk only after posting...

UK moved to metric like other European countries?
Maybe mixture, Imperial and Metric? If so, what is more used in the UK?
Thank You

SimonG · Dec 3, 2017

Ric2013 · Dec 4, 2017

We use metric copper and plastic, in 15mm and 22mm, these being roughly equivalent to half and three quarter inch bore copper. In steel, we continue to use imperial (inch) sizes and BSP threads. Threads tend to be BSP as Simon has said, so we often use 1/2"BSP x 15mm connectors, for example.
Continental Europe tends to use copper pipe in 10/12/14/16mm sizes, not our 15mm, thus we continue to be weird and different, but they use a lot of steel and in imperial sizes (not metric, not in Italy, anyway). And our plumbing systems have, historically, been very different (and still are not altogether the same).

rony · Dec 4, 2017

Thank for making me more confused 😕

Ric2013 · Dec 4, 2017

Summary
Copper and plastic in UK: metric.
Threads in UK: generally British standard pipe
Steel pipe in UK: Imperial (inch) sizes
Plastic waste pipe in UK: described in metric external diameter sizes, but very often referred to by the type of plastic and approximate nominal bore in inches.

Yes, the UK is metric, but the plumbing practices common in UK are often different from those on the continent. Also, although we do use metric sizes of copper pipe, we rarely use or have access to the same sizes of pipe as the continentals do.

Afraid I can't make it simple, because it isn't.