BSP thread sizings

PeteW

Hi, I'm a bit confused by BSP thread sizes.

I bought this 22mm x 3/4" tank coupler. The thread measures at around 26mm which (despite being roughly an inch!) is indeed 3/4" BSP according to the table here.

So I bought a 3/4" brass cap for it, and it doesn't fit...! The thread inside seems to measure around 27mm at its widest.
The compression nut from the end of the coupler measures around 30mm at its widest and obviously that fits fine.

So any suggestions what size end cap I should buy for this fitting?

Thanks

Pete

Alex1983

Use a 22mm end cap and a small piece of 22mm copper or a 22mm blanking cap.

MisterP123

Alex1983 wrote: »

Use a 22mm end cap and a small piece of 22mm copper or a 22mm blanking cap.

This. ^^^^

22mm compression fittings don't use BSP threads. They use whatever die they have lying around on the factory floor that particular day, then rummage for a nut that fits. On the other hand, 15mm fittings are indeed 1/2" BSP.

No doubt there are exceptions.

Ganga

MisterP123 wrote: »

This. ^^^^

22mm compression fittings don't use BSP threads. They use whatever die they have lying around on the factory floor that particular day, then rummage for a nut that fits. On the other hand, 15mm fittings are indeed 1/2" BSP.

No doubt there are exceptions.

What a load of rubbish!,British Standard Pipe Threads have been around for a long time and the word Standard tells you something.
If you bought the tank coupler to blank off a hole just buy a 22mm stopper and fit on the end as suggested by Alex1983

MisterP123

Ganga wrote: »

What a load of rubbish!,British Standard Pipe Threads have been around for a long time and the word Standard tells you something.
If you bought the tank coupler to blank off a hole just buy a 22mm stopper and fit on the end as suggested by Alex1983

Erh, no mate.

Not sure you know what you're talking about. You can't buy a 22mm stopper. The OP assumed he could blank it off with a BSPP end cap but as i said, the 22mm compression nut almost always uses a thread set out by the manufacturers, often a much finer pitch than BSPP. So easiest solution is to fit a bit of pipe then cap the pipe with a 22mm blank.

But hey! I obviously don't know what I'm talking about :rotfl:

Ganga

MisterP123 wrote: »

Erh, no mate.

Not sure you know what you're talking about. You can't buy a 22mm stopper. The OP assumed he could blank it off with a BSPP end cap but as i said, the 22mm compression nut almost always uses a thread set out by the manufacturers, often a much finer pitch than BSPP. So easiest solution is to fit a bit of pipe then cap the pipe with a 22mm blank.

But hey! I obviously don't know what I'm talking about :rotfl:

Erh,yes mate,you do not know what you are talking about when you say
" they use whatever die is lying about on the floor" every fitting is machine made by the thousand,so tooled up from scratch.
I also do not know what i am talking about as i am now retired but worked on compressed air tools,installations all my working life.They all used BSP fittings,even the plastic glued together systems ended with screw ends for the customers choice of connections.:rotfl:

Alex1983

The fitting in the link is a 22mm compression so a 22mm blank cap will be fine or a small bit of 22mm copper capped off.

Always thought the 3/4 bit of this fitting related to the hole in the tank, maybe I'm wrong but think you find the 3/4 bit is irrelevant to what your trying to do.

MisterP123

Ganga wrote: »

Erh,yes mate,you do not know what you are talking about when you say
" they use whatever die is lying about on the floor" every fitting is machine made by the thousand,so tooled up from scratch.
I also do not know what i am talking about as i am now retired but worked on compressed air tools,installations all my working life.They all used BSP fittings,even the plastic glued together systems ended with screw ends for the customers choice of connections.:rotfl:

That was a bit of sarcasm. I was just stating the fact that the threaded end for a 22mm compression nut is not the same as a 3/4" BSP thread. It's usually a much finer pitch and not all manufacturers will use the same thread.

Wonder how many of them mashed together fittings you made in your working life have failed.... :rotfl:

PeteW

So… would one of these do the job? http://www.screwfix.com/p/22mm/80500

Alex1983

Yes it will be fine, I'd put a 3/4 fibre washer in the cap

PeteW

Great, thanks.

And the other thing I need, is a means of connecting the tank coupler to a fan housing (as you can tell this isn't for plumbing! It's a little electrical gadget I'm building). So I need a female threaded adapter on one end and some form of male cylindrical outlet on the other - circumference doesn't matter as the fan housing will be 3D printed to suit.

I think this would do it - http://www.toolstation.com/shop/p47549
But just to confirm, would that nut fit my coupler's thread, and then the pipe bit coming out would be 22mm would it?

Thanks

Pete