# Anybody Here Familiar With Pipe Thread Standards?

#### Visitor

##### Well-Known Member
This question is kind of electronics-related, since it's about the threads on Chinese flow sensors, and I know there's an abundance of experience here....

#### Les Jones

##### Well-Known Member
In the UK 3/4" BSP is a common size for the hose connector on outside taps.
This is an example of the hose connector. It would need a rubber washer or "O" ring to make the seal.

Les

#### Nigel Goodwin

##### Super Moderator
Thanks Gentlemen, that helps my education along. The seal washers are something I've never seen and wouldn't have thought to get if I purchase other fittings.

Here's a picture of the type of flow meter I'm looking at. These things appear to have pretty good engineering for the \$10 price. The impeller spins a magnet, which is picked up by an external Hall effect sensor, so no seal to worry about.

View attachment 130704
Yes, I've played with that exact sensor - it simply connects with the old UK screw-on hose fittings - but everything now seems to be Hoselock, and 3/4" to Hoselock fittings are commonplace.

Here are the ones we use:

https://cpc.farnell.com/hozelock/2175/outdoor-tap-garden-hose-connector/dp/SI15639 there's a rubber seal in the adaptor, so no extra one required.

We don't use the white part, but I can't bring myself to throw them away, so I've got a fair pile of them now. Just don't lose the rubber seal when you unscrew the white part (and not notice) as it WILL leak with out the rubber seal.

#### rjenkinsgb

##### Well-Known Member
Searching Amazon.com for something to fit the flow meter produces adapters for 3/4 "hose thread" - I think Les has found the compatible fittings, apparently garden hose connections in the US use 3/4" BSP the same as in the UK?

You may also find that a 3/4 NPT barrel connector fits straight on the plastic thread, though?

3/4" is also the standard for bath tap plumbing fittings in the UK - I have no idea what is used in the USA; are those also teh same?
eg.

ps. Those dowty seal washers are intended to go outside the thread of a fitting. Internal washer fittings generally use either rubber or fibre seals.

#### Les Jones

##### Well-Known Member
Another source of these connections is the water feed hose to washing machines.

Les.

#### Visitor

##### Well-Known Member
I was just looking at garden hose fittings. Again, the US has to do things its own way.

From Wikipedia:

" In other countries, a British Standard Pipe (BSP) thread is used, which is 3⁄4 inch (19 mm) and 14 TPI (male part outside diameter is 26.441 mm or 1.04 in). The GHT and BSP standards are not compatible, and attempting to connect a GHT hose to a BSP fitting, or vice versa, will damage the threads. "

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#### rjenkinsgb

##### Well-Known Member
attempting to connect a GHT hose to a BSP fitting, or vice versa, will damage the threads.
Doh... I'd see if NPT will fit, at least they are the same thread pitch...

#### Visitor

##### Well-Known Member
G3/4 is a US garden hose connector.
Not so according to Wikipedia, as I posted in post #10.

" In other countries, a British Standard Pipe (BSP) thread is used, which is 3⁄4 inch (19 mm) and 14 TPI (male part outside diameter is 26.441 mm or 1.04 in). The GHT and BSP standards are not compatible, and attempting to connect a GHT hose to a BSP fitting, or vice versa, will damage the threads. "