UPDATE (5/16/11) How many of your PIT drivers know what that little hole in the propane cylinder protective valve collar is really for?  Next time you walk by a PIT, check to see if the cylinder is installed properly.  Here is a tip...

I received over 20 e-mails overnight asking me about this post.  The main theme of almost all the e-mails is asking if this is a regulatory issue.  To be very clear, OSHA will NOT cite your facility for not having the "peg in the hole", but they will cite your facility if the user has the cylinder positioned in such a way as to NOT have the relief valve in the vapor space. If the "peg is not in the hole" and it is a FULL cylinder, there is a VERY GOOD chance that the relief valve will not be in the vapor space when the cylinder is first placed into service.  ANOTHER item that you may need to check is your storage bins to ensure the delivery person is loading the bins with the relief valves UP.

1910.110(b)(10)(ix) Safety relief valves shall have direct communication with the vapor space of the container at all times.

Positioning the cylinder properly is essential for the propane in the bottle to be used completely and SAFELY.   Similar to that of a battery, you want to make sure all available FUEL has been used before replacing it. Properly mounting the cylinder ensures that the liquid can be withdrawn through the service valve by way of the liquid service diptube. The propane liquid diptube in a forklift cylinder operates in the same manner as a liquid withdrawal valve. The cylinder service diptube communicates with the liquid space of the cylinder when installed vertically or mounted horizontally in the correct position. Forklift cylinder neck rings (collars) have orientation holes to position the cylinder properly on the bracket orientation pins. Correctly mounting the cylinder in its proper position will allow continuous operation of the forklift and use of all propane in the cylinder.  See photo of PROPER Mounting below...

Forklifts with improperly mounted cylinders will generally stop operating before the bottle is empty. Without correct alignment of the cylinder and bracket orientation pin, the liquid level will fall below the service diptube and propane liquid will no longer be withdrawn from the cylinder, shutting down the forklift engine. The forklift will run once the cylinder has properly been repositioned, allowing liquid propane to flow through the service diptube. Remember that forklifts run on propane liquid, not on vapor. Incorrect mounting of a forklift cylinder on a lift truck will cause the lift to stop running before the bottle has run out of gas. If the cylinder is returned with gas in it to the supplier, the lift owner or operator loses money.