Abstract: A control system for the operation of a centrifugal pump which may be used for production of gas and/or oil from a well. The control system includes vector feedback model to derive values of torque and speed from signals indicative of instantaneous current and voltage drawn by the pump motor, a pump model which derives values of the fluid flow rate and the head pressure for the pump from torque and speed inputs, a pumping system model that derives from the estimated values of the pump operating parameters an estimated value of a pumping system parameter and controllers responsive to the estimated values of the pumping system parameters to control the pump to maintain fluid level at the pump input near an optimum level.

Abstract: A liquid separator for a respiratory gas sample analyzer includes a closed container having a liquid trap filter chamber integral with the container. The liquid trap filter chamber includes an inlet compartment and an outlet compartment. The inlet compartment is interposed between a sample inlet port and a sample outlet port and includes a gas permeable, liquid impermeable filter element for separating liquid from a gas sample, the liquid separated from the gas sample passing to a collection chamber. The outlet compartment includes a further gas permeable, liquid impermeable trap filter element which is interposed between the collection chamber and a low pressure port, for preventing the flow of liquid through the output compartment to the low pressure port.