Fluid flow indicator with automatic alarm timer for high pressure/low flow applications

A fluid flow switch and alarm apparatus for detecting exceptionally low rates of fluid flow and producing an alarm warning, comprising:

• (a) a housing having an inlet port, an outlet port and an inner piston cylinder extending between and communicating with said inlet port and said outlet port so as to facilitate passage of a fluid therebetween;
• (b) a piston carrying a seal within said piston cylinder and being movable in sealed relation against an inner wall surface thereof between a resting position and a position where an electrical switch is first activated in response to the presence of said fluid flowing through said piston cylinder, said piston being constructed to block free flow of said fluid between said inlet port and said outlet port when positioned between said resting position and said position where said electrical switch is first activated;
• (c) said electrical switch being adapted to be magnetically activated by a switch-activating magnet carried by said piston when said piston is located in said position where said electrical switch is first activated;
• (d) a vent hole extending through said piston to facilitate controlled dissipation of said fluid through said piston and the return of said piston to said resting position upon a stoppage of said fluid flowing through said piston cylinder;
• (e) a piston biasing member carried within said piston cylinder for urging said piston toward said resting position upon a stoppage of said fluid flowing through said piston cylinder;
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• (f) a power source and wireless transmitter connected to said electrical switch, whereupon activation of said electrical switch transmits power from said power source to said transmitter, thereby causing a wireless signal to be transmitted to a receiver for activation of an alarm.

A fluid flow switch for detecting exceptionally low rates of fluid flow, comprising:

• (a) a housing having an inlet port, an outlet port and an inner piston cylinder extending between and communicating with said inlet port and said outlet port so as to facilitate passage of a fluid therebetween;
• (b) a piston carried within said piston cylinder, said piston carrying an elastomeric seal disposed in sealing relation between an outer surface of said piston and an inner wall surface of said piston cylinder, said piston being movable in sealed relation to said piston cylinder from a resting position to a position where an electrical switch is first activated in response to the presence of said fluid flowing through said piston cylinder, and said piston being constructed to block free flow of said fluid between said inlet port and said outlet port when positioned between said resting position and said position where said switch is first activated;
• (c) said electrical switch being adapted to be magnetically activated by a switch-activating magnet carried by said piston when said piston is located in said position where said switch is first activated;
• (d) a vent hole extending through said piston in a direction generally parallel to the axis of said piston cylinder, said vent hole being sized appropriately to control dissipation of said fluid through said piston upon a stoppage of said fluid flowing through said piston cylinder and the return of said piston to said resting position, yet restrict the flow of said fluid through said piston sufficiently to cause said piston to move toward said position where said switch is first activated in response to the presence of said fluid flowing through said piston cylinder;
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• (e) a mechanical spring carried within said housing for biasing said piston toward said resting position upon a stoppage of said fluid flowing through said piston cylinder.