Point of lube monitor

A flow sensing device comprising:

• a fitting having a channel therethrough with an inlet for receiving a flow of fluid under pressure and an outlet for discharging said fluid;
• a magnetic piston reciprocably carried in said channel and having a front face exposed to said fluid flowing in through said inlet;
• biasing means for urging said piston towards said inlet to a first position within said channel;
• an end cap mounted to an end of said piston opposite said front face, said end cap arranged between said biasing means and said piston;
• a bypass passage having an inlet in communication with said channel in a portion of said channel occupied by said piston when said piston is in said first position, said piston closing said inlet when in said first position and having an outlet communicating with said channel upstream of said channel outlet;
• a stop means fixed in position with respect to said barrel and abuttable to said end cap for limiting movement of said piston toward said inlet to said first position;
• a magnetic sensing mans outside of said channel in magnetic communication with said magnetic piston for registering a signal corresponding to movement of said magnetic piston in said channel;
• whereby, when said fluid under pressure flows into said fitting it impinges on said front face of said piston moving it against said biasing means toward said outlet to expose said bypass inlet allowing said fluid to flow through said bypass passage to said channel outlet.