Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some compressor
fittings that have a 1/4" female connector but when I measure the diameter
of the 'hole' of thread it looks to be a good 1/2" What exactly is being
measured when they say this is a 1/4" fitting.

More specifically I have a spare air tank that has a 1 1/2" 'hole' what size
fitting should I get for this ?

Thanks

Jim

Jim wrote in message ...
Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some compressor
fittings that have a 1/4" female connector but when I measure the diameter
of the 'hole' of thread it looks to be a good 1/2" What exactly is being
measured when they say this is a 1/4" fitting.

More specifically I have a spare air tank that has a 1 1/2" 'hole' what
size
fitting should I get for this ?

Thanks

Jim



Pipe thread sizes are based on the bore of old style, thick wall iron pipe.

With newer pipe manufacture techniques and different materials etc, it is
rare to measure anything 1/2" about 1/2" pipe or fittings.

Look up thread tables for BSP on the web and use these to help identify your
threads.

hth

Bob

On Mon, 23 Jan 2006 20:32:35 GMT, "Bob Minchin"
wrote:


Jim wrote in message ...
Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some compressor
fittings that have a 1/4" female connector but when I measure the diameter
of the 'hole' of thread it looks to be a good 1/2" What exactly is being
measured when they say this is a 1/4" fitting.

More specifically I have a spare air tank that has a 1 1/2" 'hole' what
size
fitting should I get for this ?

Thanks

Jim



Pipe thread sizes are based on the bore of old style, thick wall iron pipe.

Which, of course, makes much more sense than the current method of
designating pipes by their outside diameter, since they (normally)
carry their contents down the inside :-)

"Frank Erskine" wrote in message
...
On Mon, 23 Jan 2006 20:32:35 GMT, "Bob Minchin"
wrote:


Jim wrote in message ...
Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some
compressor
fittings that have a 1/4" female connector but when I measure the
diameter
of the 'hole' of thread it looks to be a good 1/2" What exactly is
being
measured when they say this is a 1/4" fitting.

More specifically I have a spare air tank that has a 1 1/2" 'hole' what
size
fitting should I get for this ?

Thanks

Jim



Pipe thread sizes are based on the bore of old style, thick wall iron
pipe.

Which, of course, makes much more sense than the current method of
designating pipes by their outside diameter, since they (normally)
carry their contents down the inside :-)

More a shift of emphasis - when pipe sizes came originally from the
requirements of flow calculations, the bore was, of course, important and a
fitter would ensure all went together. Now no-one does flow calculations and
fitters are less skilled, the external physical size is more convenient.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

Jim wrote:
Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some
compressor fittings that have a 1/4" female connector but when I
measure the diameter of the 'hole' of thread it looks to be a good
1/2" What exactly is being measured when they say this is a 1/4"
fitting.

A 1/4" bsp male thread will have a major diameter of 0.518" so this looks
like a 1/4" bsp.

More specifically I have a spare air tank that has a 1 1/2" 'hole'
what size fitting should I get for this ?

Don't have info for 1.1/2" but if its nearer 1.3/8" its 1" bsp. Next size
up would be 1 1/4" bsp at about 1 5/8", but 1 1/4" isn't a common size
AFAIK.

Dave

In an earlier contribution to this discussion,
Jim wrote:

Hi guys

Can anyone explain how BSP fitting are sized ?? I've got some
compressor fittings that have a 1/4" female connector but when I
measure the diameter of the 'hole' of thread it looks to be a good
1/2" What exactly is being measured when they say this is a 1/4"
fitting.
More specifically I have a spare air tank that has a 1 1/2" 'hole'
what size fitting should I get for this ?

Thanks

Jim

It's probably one-and-a quarter-inch BSP. This has the following dimensions:

Full diameter of thread: 1.650"
Core diameter of thread: 1.534 (which is waht you see if the measure the
inside of a female thread)
TPI: 11
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

It's probably one-and-a quarter-inch BSP. This has the following
dimensions:

Full diameter of thread: 1.650"
Core diameter of thread: 1.534 (which is waht you see if the measure the
inside of a female thread)
TPI: 11
--

Thanks to all for the info, checked out a couple of websites and those
tables make sense now !

I measured the thread again with a vernier caliper and it's 1.53" so looks
like it definitely is a 1 1/4" fitting.

Cheers

Jim