Abstract: An automatically-calibrating electrically-controlled diaphragm valve actuator has a stepper motor controlled by a controller mechanism for moving the actuator within a diaphragm valve. A reference position indicator is provided to signal the controller mechanism when the valve actuator is at a reference position within the actuator's linear stroke. A method for automatically calibrating an electrically controlled diaphragm valve actuator includes the following steps. The actuator is initially driven to a reference position. Second, the actuator is driven a first number of steps. Third, the actuator is returned to the reference position. Fourth, it is determined whether fall back has occurred. Fifth, a second number of steps is determined based upon whether fall back has occurred. Sixth, the actuator is driven the second number of steps in order to compensate for the fall back.

Abstract: A process for controlling an absorbent-refrigerant solution concentration in an absorption cooling system to prevent crystallization of the solution in which the crystallization temperature of the absorbent-refrigerant solution is calculated and the temperature of an absorbent-enriched solution, or strong solution, from the absorption unit heat exchanger is measured. Based upon the crystallization temperature and the measured absorbent-enriched solution temperature, the concentration of the absorbent is calculated using an iteration algorithm. Based upon the calculated concentration of absorbent in the absorbent-enriched solution, the concentration of the absorbent-enriched solution is adjusted by adjusting the heat input to the absorption system generator to prevent crystallization of the absorbent.

Abstract: An automatically-calibrating electrically-controlled diaphragm valve actuator has a stepper motor controlled by a controller mechanism for moving the actuator within a diaphragm valve. A reference position indicator is provided to signal the controller mechanism when the valve actuator is at a reference position within the actuator's linear stroke. A method for automatically calibrating an electrically controlled diaphragm valve actuator includes the following steps. The actuator is initially driven to a reference position. Second, the actuator is driven a first number of steps. Third, the actuator is returned to the reference position. Fourth, it is determined whether fall back has occurred. Fifth, a second number of steps is determined based upon whether fall back has occurred. Sixth, the actuator is driven the second number of steps in order to compensate for the fall back.