Abstract: A vacuum system for a vacuum sizing tank utilizing electronic controls to maintain the proper negative pressure within the tank. A transducer measures the tank's vacuum. An electronic circuit compares the measured value with the preset value. Any discrepancy between the two undergoes resolution by varying the voltage applied to the variable-speed d.c. controlled vacuum pump. The resulting changes in the motor's speed brings the tank's vacuum to the desired magnitude. The continuous measurement of the vacuum and its feedback to the speed of the vacuum pump results in the maintenance of the desired vacuum within the sizing tank.