spark arrestors/check valves
 

Where is the most effective placement of these. At the torch or at the regulators? Thank You.

I am sure you will hear more on this.

This implies that the best placement is at the torch, but does not state it explicitly.
http://files.aws.org/technical/facts/FACT-28.pdf

If no one else provides input, I will update references as I get access to them.

At torch.... Placing FB arrestor at torch protects hose and regulator, placing FB arrestor at regulator only protects regulator... Be aware where the FB arrestor in intended to be placed (yes there is two types) and watch the direction of low arrow...

Dale

Thank You, makes perfect sense. I appreciate your answers.