Why shut-off and non-return valves are coupled in the boiler feed line?
29 Jun '18, 15:50
Two shut-off valves required for isolation purposed in case one of them starts leaking. The main function of the non-return valve in the pair is to prevent the steam and water in the boiler from discharging out by the feed line if a feed line fracture or a joint in the line blows.
29 Jun '18, 15:55