Perhaps a picture of what you're referring to might be of value here

Matt is talking about a shield for a gas bottle that lacks an integral welded valve shield. To be effective, the bottle would need to be manufactured to accept them, as his supplier suggests a guard that was retained by the valve stem wouldn't improve the situation

Valve guard
A device that is securely fixed around the valve, but stands taller than the highest point of the valve. Guards can be of cast or welded metallic construction or made from non-metallic moulded plastics. They are often attached to the cylinder shell via a neck ring with a screw mounting, a clamp design or a circlip.

BOC Bottle Handling Guide here

The BOC Guide (thanks for sharing Steve) is well laid out and contains good information. It references, value guards, rings and caps, however is quite silent on when where and what.

however is quite silent on when where and what. — Matthew Bennett

You could try PTR Group Matt, US based but they may be able to point you in the direction of a local agent/ or Aussie one.

https://www.ptrgroup-mfg.com/products/valve-protection/guards/

It's quite a comprehensive page with different options/construction sizing etc :smile:

The BOC Guide (thanks for sharing Steve) is well laid out and contains good information. It references, value guards, rings and caps, however is quite silent on when where and what. — Matthew Bennett

Section 5.5 of Worksafe's guide for Gas Cylinders provides a bit more details for "when, where and what"

It is important that all users of cylinders take appropriate steps to ensure that
cylinder valves are protected against damage.
Examples of appropriate steps include:
a. Valve protection rings, where these form part of the cylinder design
b. Vented valve caps, where threaded provision for these has been provided
c. Protecting the tops of cylinders during transport and handling, or
d. Securing tall cylinders during transport and storage to prevent them from toppling.

While it is implied that not all of these need to be done (with the "or" at the end) the question to the supplier if their intended method of protection is to ensure the cylinders are chained up is what is the plan for a case like the linked video when a cylinder is being moved and potentially left to stand unsecure for a moment while doing so?

1) valve guards are useless because you can't attach a regulator to the bottle — Matthew Bennett

Are they misunderstanding the purpose of the threaded valve guards/caps? My understanding is these are installed when the cylinders are being transported/moved (and therefore not chained up), not when they are in use. Once in position and secured, the cap can be removed and regulator fitted.
Am I missing something?

Mostly on point Matt. Yes; valve caps sit over the valve, ideally used for transport. While in place, nothing can be attached to the bottle and they protect the valve from impact / shearing forces.

Valve Rings or Guards (like the ones shown in photo above) allow access to the valve, allowing the bottle to be used while still offering protection to the valve.

I was told be one supplier that a valve guard is "useless because you can't attach a regulator, so you can't use the bottle". The photo shows that this is clearly wrong, however in fairness they may have been confusing a valve guard with a valve cap, or referring to the fact that if a bottle falls over with a valve guard and a regulator attached the regulator could still be impacted.

Chaining up will always be the first preference to protecting the valve. A cap, guard or ring has definite benefit in transitions, such as when moving a bottle from storage onto a trolley. The clear advantage of a guard or ring is that it in place and doesn't require additional steps from operators (Install cap, relocate / move bottle, remove cap, attached regulatory or hose), significantly reducing process deviation. There are also situations when a bottle is in use and chained up, however the valve is still at risk of impact or shear forces.

Only one of the three major gas suppliers I've talked to provide valve guards on all their bottles. It is actually one of their points of difference, using the safety call. And I still haven't been able to find a supplier of after-market valve guards in NZ. I would argue that these two points (2/3 of industry suppliers aren't doing it and you cant get them) make a strong position that valve guards are not a practicable step. I haven't been able to assess the financial impact.

I did do some Friday end of day napkin math with a colleague and worked out the a 45kg gas bottle could generate a 40Kj shearing force on the valve when it falls over. One person I talked with said in passing that bottle valve in NZ had to be rated to 4Kj (I haven't been able to find this in any standard, so can't verify yet) and that his were rated to 40Kj. That doesn't seem like much of a safety margin to me. Suffice to say I'm going to do some testing. I think it'll be fun ;-)