Patent ID: 8027751

Claim:
A fluid delivery system for delivering a metered dose of fluid from a supply tank ( 28 ) to a downstream chamber or vessel ( 10 ), the system comprising: a pump apparatus ( 20 ) comprising a pump plunger ( 32 ) which is operable to perform a pumping stroke under the control of an electromagnetic actuator ( 36 ), including a solenoid ( 36 a ), to effect delivery of the fluid, a control unit ( 24 ) for supplying an input signal ( 58 ) to the solenoid ( 36 a ) to initiate a current flow to the solenoid ( 36 a ) and thereby initiate movement of the pump plunger ( 32 ), an electronic device ( 54 ) which provides an output signal to indicate that movement of the pump plunger has stopped at the end of the pumping stroke, a timer for determining a time difference between the input signal ( 58 ) being supplied to the solenoid ( 36 a ) and the output signal being output by the electronic device ( 54 ), and a processor ( 26 ) for comparing the time difference with a predetermined time difference and determining, as a result of the comparison, whether or not the pump plunger ( 32 ) has performed a valid pumping stroke in which an intended volume of fluid is displaced.