Abstract: A sensing system for detecting a low level of liquid in a container employs an open-ended probe which is partially submerged in the liquid. The probe contains a pressurized compressible fluid, typically air, the pressure of which is related to the level of the liquid in the container, being a function of the static head of the liquid. A pressure switch fluidly connected to the probe is actuated when the pressure in the probe falls below a predetermined level. The pressure switch activates an air pump, which pumps compressed air into the probe to try and restore the predetermined pressure level, and the switch simultaneously actuates a time delay unit, which in turn initiates a time delay period. If pressure in the probe is restored to the predetermined level prior to the expiration of the time delay period, the time delay unit is reset and the air pump is shut off, since restoration of the pressure indicates that the liquid level is not really low, the low pressure condition is caused by a leak or absorption.

Abstract: A peristaltic feed pump, driven by a shaded pole motor, is provided to feed sticky, thixotropic fluids such as soaps, detergents, rinse additives, etc., to a dishwasher, chemical reactor, and the like. The shaded pole motor comprises a constant torque, A.C. portion and a D.C. electromagnetic brake portion.The net effect of the motor enables the fluid to be fed to the dishwasher by the pump within reasonable limits of linearity.