Patent ID: 7241115

Claim:
A pumping apparatus for pumping fluid comprising: at least one pumping chamber having an inlet and an outlet, said pumping chamber having a piston for movement in said chamber which piston propels said fluid from said chamber, said inlet for receiving fluid from a fluid supply and said outlet for discharging said fluid from said chamber; at least one motor for powering said piston in said pumping chamber, said motor operating in a pumping mode upon receiving a pumping signal; at least one inlet valve in fluid communication with said inlet of said pumping chamber, said inlet valve having an open position and a closed position; at least one switchable valve in fluid communication with said outlet of said pumping chamber, said at least one switchable valve having a closed position and an open position, and said at least one switchable valve assuming said closed position upon receiving a close signal; at least one first pressure measuring device in fluid communication with said pumping chamber, between said inlet valve and switchable valve, said at least one pressure measuring device producing a pressure signal in response to pressure; control means for receiving said pressure signal, for sending a close signal to said at least one switchable valve and for sending a pumping signal to said motor, said control means having a test mode in which said control means send a pumping signal to said motor, sends a close signal to said switchable valve to cause said fluid in said chamber to be placed under a pressure, said first pressure measuring device determining a first threshold pressure at a first time and sending a first threshold pressure signal to said control means, said first pressure measuring device determining at least one second threshold pressure at a second time and sending a second threshold pressure signal to said control means, said control means calculating the slope of a line representing the difference of said first threshold pressure signal and said second threshold pressure signal over time and comparing said slope with a threshold value, said threshold value representing a leak in the pump, said control means sending one or more error messages to the operator in response to said slope exceeding said threshold value.