Air gas/ratio valve and zero governor

[Jack Mckeown]

was just wondering whether someone could explain the purpose/operation/faults associated with one of these valves.
Sorry in advance if this is in the wrong thread I did not know where to put it.

 

[ShaunCorbs]

May I ask the reason behind the question?

 

[Jack Mckeown]

May I ask the reason behind the question?

I’m studying my gas and have my ACS in May, but my gas viper book doesn’t describe much on this particular valve, and I’m on block release every 5 weeks so I can’t ask my tutor at the moment.