Nozzle condition monitor

Claim 1

Apparatus for monitoring liquid flow through a conduit leading to a nozzle comprising: (a) a nonmagnetic housing having an up-right passage therein having upper and lower ports opening into each end of the passage, (b) a removable hollow nonmagnetic sleeve disposed within the up-right passage, (c) a magnetic piston arranged within the sleeve such that flow may take place along the sides of the piston from the lower port to the upper port and such that when the flow is sufficient, the piston is carried upward within the sleeve, (d) stoppers arranged to hold the sleeve within the up-right passage and to restrict the travel of the piston to prevent the piston from moving into a position adjacent to either port, (e) a magnetic switch arranged near the up-right passage near one of the extremes of travel of the magnetic piston such that when the piston is at one of its extreme positions it will close the magnetic switch, and (f) means for detecting the condition of closure of the magnetic switch to produce an electrical signal indicative of whether or not flow through the passage is taking place.