Tank Valve IDs and Max Fill Pressures

[Bob DBF]

The actual mass of brass in the cylinder neck (aka the valve) doesn't have a pressure rating per se like the OP is asking.

What might cause the confusion is that tanks now come with a plate on them with the service pressure of the tank on them, and the one he got didn't.

 

[captain]

Any valve at any pressure is only as strong as the threads on the valve and the threads on the tank. Threads on a brass valve are stronger than threads in an aluminum tank and weaker than the threads in a steel tank.
If the tank of any material doesn't fail and the valve has no burst disc and if the pressure is increased high enough the threads will fail eventually before anything else.
Force on a valve is in pounds per unit area. A 3/4" valve is about 1" in diameter with an area of .78 square inches. At 3000 psi the psi on the valve 2340 psi. I have no idea what the failure pressure of the threads might be but it is dam sure much higher than that of the tank it self or else the tank couldn't the tested to failure.

 

[happy-diver]

and with double burst discs I've never extruded a yoke oring at pressures far exceeding anything spoken about here

 

[Steven Bird]

Ok, this might help. I have two 240Bar WP AL80 tanks.

The right side one is branded "Sea Hornet" (original sticker) but has Luxfer stamping. It is 240 Bar WP. The valve is marked Sea Hornet (TD Preece), 240Bar. It has a burst disk plug labelled "To suit Cyl FP24 TP36"

The left side tank has CIG stamping and is 240Bar WP. The valve is only labelled "38-95, K 491". It has a burst disk plug labelled "36MPA 24-95"

Everything about the valves other than the writing are identical in appearance, right down to the plastic knob. So Im pretty such these are both made by Sea Hornet (TD Preece) in Australia who have gone out of business ~2018.

Im trying to determine what the max fill is in Australia, using yoke. One very experienced person said they only fill AL tanks for yokes to 227 Bar as a policy, while another equally experienced person said they are happy to fill to 240Bar if the tank is labelled as such.

Any thoughts on what the guidelines are in Australia?

What do the "38-95" and "24-95" mean. Service pressure and fail pressure in MPA?

The

 

[OMyMyOHellYes]

burst disks are same as the hydrostatic test pressure. For Al80s that's 5000 psi

The chunk of brass can withstand that just fine but the yoke on the reg and the oring will be very unhappy. Yoke valves are not used >3000psi

Partially true. US says 3,000# standard; internationally, outside US, the same yokes are rated to 3,442# (232 bar).

 

[iointerrupt]

What do the "38-95" and "24-95" mean.

Manufacture date, 38th week of 1995.

I'd say if you have a valve that says 240bar, a tank that says 240bar, and it's been properly hydrostatically tested at that pressure, no reason it can't be filled to 240bar.

Probably just have problems with fill stations because it's an unusual setup, 240bar aluminum tanks aren't manufactured anymore as far as I know.

 

[rjack321]

Partially true. US says 3,000# standard; internationally, outside US, the same yokes are rated to 3,442# (232 bar).

Is that so? Who is doing this "rating" and where can I find those ratings?

(hint) US DOT and CGA don't care about the various outlet types in scuba tanks.

 

[OMyMyOHellYes]

Is that so? Who is doing this "rating" and where can I find those ratings?

(hint) US DOT and CGA don't care about the various outlet types in scuba tanks.

I was going by what that guy rjack said re: the 3,000 limit.