i have a tank question

[philipvenero]

i have a steel tank its gray and hasnt been hydro tested since 88. i have a problem it has a j valve on with a small diameter thread. newer tanks have a bigger one. i want to put a k valve on it anyone know were i can get a small size one.

 

[Gen San Chris]

Get it hydro tested first, if it is OK then look for a new valve! I still have one steel tank with a small thred valve, its a US Divers valve so if you contact them maybe they can fix you up!

 

[matt_w]

i have a steel tank its gray and hasnt been hydro tested since 88. i have a problem it has a j valve on with a small diameter thread. newer tanks have a bigger one. i want to put a k valve on it anyone know were i can get a small size one.

If your tank is marked DOT-Exxxx-3500, you most likely have 7/8 UNF thread Size (Sounds bigger but it is actually a smaller hole than common 3/4 NPSM on most current tanks)

Scuba.com 7/8 UNF , but the cost is $129. There is a chance your tank will not pass Hydro, so I would not buy the valve before you have it tested. You may be able to find the valve cheaper used, but they are pretty rare now.

Your LDS could probably order you a brand new steel tank of nearly any size for less than the cost of the valve, hydro and vis on your older tank.

Safe diving,

Matt

 

[mike_s]

If your tank is marked DOT-Exxxx-3500, you most likely have 7/8 UNF thread Size (Sounds bigger but it is actually a smaller hole than common 3/4 NPSM on most current tanks)

Maybe there is some "scuba secret" about this tank valve size..... but basic math tells me that 7/8" is larger than 3/4"

if you "double" 3/4" to a larger fraction you get 6/8".

compare 6/8" to 7/8" and.... well.... uhmmm..... 7/8" is bigger.]


maybe you know somehting about this valve that I don't, but 7/8" sure seems bigger

Scuba.com 7/8 UNF , but the cost is $129. There is a chance your tank will not pass Hydro, so I would not buy the valve before you have it tested. You may be able to find the valve cheaper used, but they are pretty rare now.

Your LDS could probably order you a brand new steel tank of nearly any size for less than the cost of the valve, hydro and vis on your older tank.

Safe diving,

Matt

you're right. for that $129 valve (plus shipping), plus the costs of a hydro, a visual and and anything else, you pretty much could get a new tank for the same cost.

 

[Stu S.]

There are valves left over when tanks are scrapped and eBay is where they go. Happy hunting.

A pipe thread has the letter "P" in it and fits a pipe that would be, say 3/4 inch on the inside. The threaded outside of the pipe is bigger. A UNF thread is a screw thread and 7/8 inch would be the actual outside diameter.

 

[captain]

If it is small thread with a J valve more than likely it is a older steel 72 with 1/2" pipe thread. If so there is no chance of finding a new valve of any type for it. There is no valid reason to replace the J valve, just leave the reserve lever in the down position.

Mike S, the 3/4" thread is pipe thread and it is designated by the ID of 3/4" pipe not the OD of the thread so it does measure bigger than 3/4". By contrast 7/8" UNF is actually 7/8" just as a
7/8" bolt is 7/8". Two entirely different measuring systems.

 

[philipvenero]

mike s im sitting here in the dark trying to smush your bug on my screen

 

[Scared Silly]

i have a steel tank its gray and hasnt been hydro tested since 88. i have a problem it has a j valve on with a small diameter thread. newer tanks have a bigger one. i want to put a k valve on it anyone know were i can get a small size one.

What is the date of the first hydro? and the rest of the crown markings. It could be 7/8" but it could also be 1/2" tappered. With a J valve I would put my money on 1/2" tappered.

Maybe there is some "scuba secret" about this tank valve size..... but basic math tells me that 7/8" is larger than 3/4"
maybe you know somehting about this valve that I don't, but 7/8" sure seems bigger

Actually, it is a common mistake. The 3/4"-14 NPSM uses a different standard than the 7/8"-14 UNF-2B

This thread might help.

http://www.scubaboard.com/forums/ta...tank-threads-what-happened-7-8-14-2a-unf.html

 

[philipvenero]

it says on the crown HEALTHWAYS L.A. CALIF. COMPRESSED AIR ONLY LCC3AA2250 L96855 PST 3662+

 

[RonFrank]

Your first step is a hydro. Don't bother doing anything else before this other than to clean the tank!

IMO if the J valve works, use it! If it does not, there are a lot of options out there, ebay, craigslist, and even..... SB! But the Hydro comes first.