involving a piston, diaphragm, or bellows, e.g. displaceable under pressure of incoming condensate

Full Title

Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers > with valves controlled by excess or release of pressure > involving a piston, diaphragm, or bellows, e.g. displaceable under pressure of incoming condensate