PDA

View Full Version : So close yet so far



Aquatrax
08-27-2009, 19:51
I just sat down at the table to assemble my doubles but to my surprise, the tanks have 1 inch valve openings rather than standard 3/4 inch. The tanks are Catalina AL80s by the way. I checked Catalina's web site but they only show a 3/4 neck opening. Has anyone ran into this before? and if so, what is the path you took.

I'm not looking forward to locating some 1 off ISO manifold or returning my tanks to Scuba Toys.

Any thoughts?

in_cavediver
08-27-2009, 20:45
I just sat down at the table to assemble my doubles but to my surprise, the tanks have 1 inch valve openings rather than standard 3/4 inch. The tanks are Catalina AL80s by the way. I checked Catalina's web site but they only show a 3/4 neck opening. Has anyone ran into this before? and if so, what is the path you took.

I'm not looking forward to locating some 1 off ISO manifold or returning my tanks to Scuba Toys.

Any thoughts?

I don't have a tank apart but remember, the 3/4 measure is the spec for the threading, not the opening of the tank.

What kind of manifold do you have? Perhaps an 'older' 7/8" genesis designed for the old HP (3500psi) steels? I can't imagine the catalina tanks are non-standard.

IndyDiver
08-27-2009, 23:18
I just sat down at the table to assemble my doubles but to my surprise, the tanks have 1 inch valve openings rather than standard 3/4 inch. The tanks are Catalina AL80s by the way. I checked Catalina's web site but they only show a 3/4 neck opening. Has anyone ran into this before? and if so, what is the path you took.

I'm not looking forward to locating some 1 off ISO manifold or returning my tanks to Scuba Toys.

Any thoughts?

I don't have a tank apart but remember, the 3/4 measure is the spec for the threading, not the opening of the tank.

What kind of manifold do you have? Perhaps an 'older' 7/8" genesis designed for the old HP (3500psi) steels? I can't imagine the catalina tanks are non-standard.

Just to clarify:

As in_cavediver said, the thread measure is not directly related to the size of the tank opening. In fact, the 7/8" threads found on older 300 bar manifolds are actually SMALLER in diameter then the newer 3/4" threads.

The 3/4" threads are really about 15/16" in diameter if you measure them, so the tank opening probably looks like 1 inch if you measure quickly.

A good link that explains all this, as well as the 200bar/300bar DIN myths, is at:
SCUBA Valves: Regulator Fittings, 200 vs 300 Bar FAQ and Cylinder Neck Threads - Dive Gear Express (http://www.divegearexpress.com/library/valves.shtml)

Aquatrax
08-28-2009, 06:31
The manifold is an OMS and appears to be a standard captured o-ring model. Threaded opening in the tank is the size of a quarter, valves on the manifold are much smaller.

I'll swing by Scuba Toys on Saturday, they have a box of manifolds to rummage through.

Thanks for the help as always guys.






I just sat down at the table to assemble my doubles but to my surprise, the tanks have 1 inch valve openings rather than standard 3/4 inch. The tanks are Catalina AL80s by the way. I checked Catalina's web site but they only show a 3/4 neck opening. Has anyone ran into this before? and if so, what is the path you took.

I'm not looking forward to locating some 1 off ISO manifold or returning my tanks to Scuba Toys.

Any thoughts?

I don't have a tank apart but remember, the 3/4 measure is the spec for the threading, not the opening of the tank.

What kind of manifold do you have? Perhaps an 'older' 7/8" genesis designed for the old HP (3500psi) steels? I can't imagine the catalina tanks are non-standard.

IndyDiver
08-28-2009, 08:15
OMS did used to make a 7/8" manifold, so I still think this is your problem.

Remember a 3/4 NPS thread uses a 15/16" tap drill, and a 7/8 UNF thread uses a 13/16" tap drill. So a 7/8 UNF threaded shaft WILL slip into a 3/4 NPS threaded hole without any screwing required.

Aquatrax
08-30-2009, 13:56
OMS did used to make a 7/8" manifold, so I still think this is your problem.

Remember a 3/4 NPS thread uses a 15/16" tap drill, and a 7/8 UNF thread uses a 13/16" tap drill. So a 7/8 UNF threaded shaft WILL slip into a 3/4 NPS threaded hole without any screwing required.

yep, it was the manifold, went to ST, picked up a 200 bar Dive Rite and all is right in my world. Know anyone looking for a 7/8 manifold?