How easy to remove/replace pony valves when traveling?

[flots am]

No torque is torque - whether applied to an apple or an orange its the same.

But you just made two opposite statements. 50ftlbs you can do by hand, and 50 ft lbs is not what you can do by hand. Either way, noone can even get close with ones hand.

Maybe you meant something else, I dunno, but ORB fittings are just slightly more than hand tight - its the o-ring that seals the pressure load, not the threads.

You could tighten your lug nuts hand tight also, if they were pressurized to 3000 PSI after mounting.

 

[PeterNBiddle]

Bottom line: If you can remove the valve without tools, it's not torqued tight enough.

You can get a torque wrench and judge for yourself. 50-foot pounds is a bit tighter than what I can achieve by hand. Your experience may be different.

The threads don't magically become stronger when you torque them. You can't increase the bearing surface, it is what it is. They do become harder to remove, which is a fine thing for a rental tank handed out to yahoos and banged around all day but I can't see how 50 lbs of torque is necessary for a tank I own, control and manage.

3000+ PSI provides massive on-demand torque and I can tell quite clearly if a tank seal is loose because... it will be leaking.

 

[Agility]

My understanding is that technically the cylinder should receive a VIP if the valve has been removed. That would incur a cost of $30-40 (2 VIPs) for each flight.

Just make sure there is nothing but dry air in the cylinder when you screw the valve on.

 

[BUDMANOK]

I print the TSA regulations sheet and tape it to the cylinder. Never had a problem. first time I removed the valve after a VIP from dive shop I could easily remove it by hand so I figured hand tight was good and the tech at dive shop said it was fine.

 

[Doc Harry]

...But you just made two opposite statements. 50ftlbs you can do by hand, and 50 ft lbs is not what you can do by hand...

You mis-read my statements, take another look.

...but I can't see how 50 lbs of torque is necessary for a tank I own, control and manage...

50 ft-lbs is only the manufacturer's specifications. Everyone is free to ignore the manufacturer's recommendations for cylinders that they own, control, and manage.

 

[KD8NPB]

Lug nuts are not high-pressure cylinders. Apple and oranges.

Lug nut torque on my Honda is about 60 lb-ft...

 

[Darnold9999]

Had an issue with my pony last trip. Hand tight - dove it for a week then could not get the valve off. Had to search the boat for a big ass wrenchto get it off. Fortunately the engineer was able to locate one big enough. Not a size that is used too often.

 

[PeterNBiddle]

50 ft-lbs is only the manufacturer's specifications. Everyone is free to ignore the manufacturer's recommendations for cylinders that they own, control, and manage.

From the below "use the least possible torque to make a leak-tight seal". Clearly least possible could be hand tight, correct?

Maximum is not a starting point.

TABLE 1
Maximum torque for North American new, straight-thread brass valves installed into new Luxfer aluminum alloy cylinders and composite cylinder liners—use the least possible torque to make a leak-tight seal
Straight-thread dimension Torque not to exceed
.625 – 18 UNF50 lbf-ft (67.7 Nm)
.750 - 14 NGS100 lbf-ft (135.58 Nm)
.750 - 16 UNF75 lbf-ft (101.7 Nm)
.875 – 14 UNF80 lbf-ft (108.46 Nm)
1.125 – 12 UNF100 lbf-ft (135.58 Nm)

http://www.luxfercylinders.com/supp...or-luxfer-aluminum-alloy-cylinders-and-liners

 

[Doc Harry]

Thanks for the data Peter. Several years ago manufactureres recommended 75 foot-pounds, then several manufactureres reduced the recommended torque to 50 foot-pounds.

Looks like the data that Peter quoted was effective as of Sunday, 20 March 2011, maximum torque is anywhere from 50 to 100 ft-lbs depending on the valve.

Gracias.

 

[maniago]

From the below "use the least possible torque to make a leak-tight seal". Clearly least possible could be hand tight, correct?

Straight-thread dimension Torque not to exceed
.625 – 18 UNF50 lbf-ft (67.7 Nm)
.750 - 14 NGS100 lbf-ft (135.58 Nm)
.750 - 16 UNF75 lbf-ft (101.7 Nm)
.875 – 14 UNF80 lbf-ft (108.46 Nm)
1.125 – 12 UNF100 lbf-ft (135.58 Nm)

Valve installation torque values for Luxfer aluminum alloy cylinders and liners - Luxfer: Setting The Standard Worldwide

NONONONONo. This is a CGA document. Damn it guys pay attention. SCUBA valves are ORB connections using viton or similar o-rings like the hoses on your 1st stage. These valves are not like NPT or PTFE ringed valves on CGA tanks.

If you have tank certs you ought to know this already or you did a scuba only cert class (which is ok, but don't extrapolate from wrong data).

Lets be clear - you may know the tank mfg name because of SCUBA, but tank mfgs make tanks for everything imaginable that can be compressed and put in them. SCUBA and SCBA are a small subset of all the tanks made. And they are unique in their design and application. Don't confuse with them with rest of the worlds compressed and liquid gas containers.