Dear,
We have fuel gas fired heaer and heater has main fuel gas line and off gas line.
Off gas duty is about 10% of total heater duty.
Main fule gas and pilot gas lines have double UVs (Shut-off Valves) and vent UV valve.
However, Off gas line has only one UV and vent UV.
Do you know why off gas line has only one UV?
Is there any possiblility of explosion when off gas UV is failed to open when required?
Off gas is generated from process and mainly methane, ethane, and propane.
Thank you.