Thread size on a cistern?

[petrolhead]

Whats the thread size on a cistern water feed?
It's the same size as that on 15mm compression glands but i'm not sure what it is.

1/2 BSP or 3/4 BSP?

Thank you for your help.

 

[Paul Barker]

1/2 in mostly but a few 3/8ths have started to appear. Yours' ll be 1/2 in though.

 

[petrolhead]

Cheers.

BSP thread sizes on fittings is not an obvious measuring exercise......

 

[chrishutt]

½" (and ¾", etc.) refers to the nominal size of the pipe bore. If you measure this it makes sense.

 

[petrolhead]

The plastic threaded pipe on a replacement cistern float valve does not have the same internal diameter dimensions as a normal pipe and measureing the outside diameter of the plastic pipe has no relation to the bsp thread size.

So, unless you work with these pipe threads regularly, there's no obvious thread size.

Recently i threaded some 2" metal pipework. The internal diameter was 2", outside OD was approx 2.5". Thread size 2"bsp.
But in normal engineering, the thread sizes are measured on the outside diameter M4,5,6,8,10,12,14,16 etc all metric threads are outside diameter.


So 1/2" bsp is the same thread size on a cistern supply and on a 15mm compression joint(copper) ball valve?

 

[doitall]

interesting to note the new steel tube and fitting sizes.

¼" is now sold as 8mm
½" is now 15mm
¾" is now 20mm
1" is now 25mm
1¼" is now 32mm
1½" is now 40mm
2" is now 50mm

So you would want an 1" x 28mm mi x copper straight coupler for a 25mm fitting

added, you were saying petrolhead