Abstract: A device for sensing fluid flow comprising a housing having an inlet and an outlet and defining a fluid flow channel between the inlet and the outlet, a first member disposed in the fluid flow channel and including at least one rigid portion, and a second member disposed in the fluid flow channel upstream from the first member and including at least one flexible portion, said flexible portion being elastically flexible between an initial position spaced from the rigid portion and with its periphery generally spaced from the periphery of the channel to define a first effective flwo area and a final position adjacent the rigid portion and with its periphery generally spaced from the periphery of the channel to a second effective flow area which exceeds the first effective flow area.

Abstract: A device for indicating differential pressures between first and second pressure sources comprising a housing with a bore and a piston member slidably disposed within the bore and dividing the bore into first and second chambers. The piston member includes a permanent magnet and the housing includes ducts for connecting the first pressure source to the first chamber and the second pressure source to the second chamber whereby the piston member is displaceably responsive to differences in pressure between the first and second pressure sources. The device further comprises indicators in cooperative arrangement with the piston member for indicating at least first and second predetermined differential pressure levels respectively corresponding to respective displacements of the piston member within the bore. The indicators are magnetically coupled to the piston permanent magnet such that they move from non-signalling to signalling positions in response to the respective displacements of the piston member.

Abstract: An automatic valve for bleeding air from liquid or with reversal of the principal elements, vice-versa. In an embodiment for bleeding free air from a hydraulic fluid reservoir or the like, a capillary extends through a movable piston in series with an orifice to differentiate between hydraulic fluid and air due to differences in the pressure drop across the capillary which results from differences in the viscosity of the fluids attempting to pass therethrough. When air, having relatively low viscosity, flows through the capillary, the differential pressure across the capillary and, accordingly, across the piston, is low and the valve remains open to bleed the air. When hydraulic fluid attempts to pass through the capillary, however, the differential pressure thereacross due to the fluid's relatively high viscosity is sufficient to move the piston and close the valve.