i dont recall ever hearing a hiss in my propane tank when opening the
valve and certainly dont smell propane.  i just went out and opened it
and the results were the same- no sound and no smell.  the soap/water
leak detection suggestion would be the first thing to do.

i generally do not open mine all the way, nor do i open my grill propane
cylinders all the way; most of time somewhere "in between". i dont
recall ever having any leaking due to only partially openning the
valves, on mine.

Stan Wilder wrote:
> I don't know where you guys come up with your crap.
> All high pressure cylinders have a double seat valve.
> In other words they must be fully closed or fully open, in either of
> these positions they seat against a seal and should not leak.
> The slight leaking in the mid range of the valve is caused by excessive
> pressure and is normal.
> Possibly a new valve might not leak in the mid range but it soon will
> with use.
> If you have a leak with the valve in full open position it could be a
> defective regulator or a leaky seat but if it only leaks during the
> transition from fully closed to fully open then its just operating
> normally.
>
> Stan Wilder
> 83 Air Cooled Westy
>