Tank Valve thread opening?

[guruboy]

What does the manifold look like?

 

[Pappy5]

What does the manifold look like?

guru,
I will post a picture of the manifold later this afternoon.
Thanks for your help..

 

[george_austin]

3/4 NPST (National Pipe Straight Thread)

 

[george_austin]

The Norris tanks are what you want - I've looked for years for LP Norris tanks and you find a doubles set in a heartbeat - nice find

 

[Pappy5]

george_austin

The Norris tanks are what you want - I've looked for years for LP Norris tanks and you find a doubles set in a heartbeat - nice find

I was talking with an older friend of mine one day and we got on the subject of diving. He's almost 65+/- years old and dove for the Navy back in the day. He said "I got an old set of doubles you can have " but the last Hydro was in 1977.
My eyes got BIG and I went and picked them up the next day, took them to a facility to have them tested. They tumbled and Hydroed them, the guy said they were in great shape. I paid $80.00 to have both tested. I carried one tank to the LDS and he did a visual and installed a new valve and filled it. The new valve was pretty pricey at the dive shop so I figured I would buy one myself online. It was a used valve described as a 3/4 but when I received it ,,it was too small. That's when I measured it with my caliber's and my confusion started...Correct me if I'm wrong---a 3/4 valve will measure a little over 1" and a 1/2 valve will measure 0.870ish which is roughly 3/4" ???

 

[grf88]

I think the 0.87 one in your photo is a 7/8" UNF valve as used on 3500 psi tanks.

 

[EricTheDood]

3/4 NPST (National Pipe Straight Thread)

This is correct.

That's when I measured it with my caliber's and my confusion started...Correct me if I'm wrong---a 3/4 valve will measure a little over 1" and a 1/2 valve will measure 0.870ish which is roughly 3/4" ???

UN = Unified National, sized is measured on the OD (outside diameter) of the thread
NP = National Pipe, size is measured on the ID (inside diameter) of the corresponding PIPE

 

[Pappy5]

What does the manifold look like?

 

[guruboy]

Yea, you'll need new valves to split your tanks.

 

[JamesBon92007]

george_austin

I was talking with an older friend of mine one day and we got on the subject of diving. He's almost 65+/- years old and dove for the Navy back in the day. He said "I got an old set of doubles you can have " but the last Hydro was in 1977.
My eyes got BIG and I went and picked them up the next day, took them to a facility to have them tested. They tumbled and Hydroed them, the guy said they were in great shape. I paid $80.00 to have both tested. I carried one tank to the LDS and he did a visual and installed a new valve and filled it. The new valve was pretty pricey at the dive shop so I figured I would buy one myself online. It was a used valve described as a 3/4 but when I received it ,,it was too small. That's when I measured it with my caliber's and my confusion started...Correct me if I'm wrong---a 3/4 valve will measure a little over 1" and a 1/2 valve will measure 0.870ish which is roughly 3/4" ???

Most likely the valve you need is probably the most common scuba tank valve in existence and and has been used on millions of steel 72s and aluminum 80s. Any dive shop ought to be able to look at your tank and instantly determine which valve you need. And yes, a 3/4" valve measures about 1". Do you have any paperwork for the valve you bought that will tell you specifically what the thread size is so you can use that information to purchase a second valve?