Pipeline flow detector using magnetic proximity switch - having great sensitivity and small pressure drop

摘要

The detector comprises a non-magnetic housing with low level fluid inlet and higher level outlet between which a float contg. a permanent magnet can be displaced to operate a mangetic proximity switch. The float slides inside a bore in which it is a very close fit with negligible lateral clearance, the lower end of the bore forming the inlet aperture to the housing. Flow from the inlet to the housing outlet is pref. via a lateral passage from the bore into an annular jacket passage coaxial with the bore. The bore is pref. the passage through a hollow cylindrical tube inserted into the housing, the lower end of the tube resting on an annular seal which forms a seat for the bottom of the float in its lowest position, so that it serves as a non-return valve. Used as an in-line detector of fluid flow through a pipeline, partic. to switch on a water treatment plant employing electric pulses.