body

valve components of

actuator

valve type
gas closed (B) - lost when the gas valve open (FO); open air (K) - lost when the gas valve closed (FC)
valve type
Air to close (B) - lost when the gas valve open (FO); open air (K) - lost when the gas valve closed (FC)
to

rated flow coefficient KV, rated stroke

medium flow, the bottom side of

To medium: the side into the bottom out