Abstract: A liquid pump control system for dry run avoidance and re-prime detection. Pump dry run conditions (such as an empty liquid source tank) can be detected with improved sensitivity by measuring pump cycle speed. Pump cycle speed is determined from sensors including pressure sensors, diaphragm end of stroke indicators, check valve movement sensors, and other techniques. The frequency content of the time-measured signal indicates pump cycle speed. When a dry run condition is detected from an increase in pump speed, a controller closes a valve to reduce pump cycle speed by reducing drive air pressure or by deadheading the pump liquid outlet. When the pump re-primes, the valve is opened, pump cycle speed increases, and pumping volume flow rate increases until a dry run condition is again encountered. Time delays can be introduced to delay shutting down or restarting the pump, for example to give a liquid source tank time to refill.

Abstract: Systems and methods for sensing positions of components are provided. In this regard, a representative method includes: capacitively coupling the component to a resistive member without electrically connecting the component and the resistive member; moving the component relative to the resistive member while the component is capacitively coupled thereto; and measuring relative electrical impedance with respect to ends of the resistive member such that a position of the component is determined.

Abstract: Various embodiments of displacement systems and methods are disclosed. One method embodiment, among others, includes providing a pulsed excitation signal to a single location of a resistive member with reference to another location of the resistive member of a displacement sensor, and responsive to the excitation signal, measuring a voltage on a non-contacting signal probe in moveable relationship to the resistive member.