These Oerlikon Leybold RUVAC vacuum pump systems include a direct mounted WH4400FC Root's blower with SOGEVAC SV630B single stage rotary vane backing pump, having a massive 3023 cfm pumping speed with an excellent ultimate pressure of 3.75 x 10-3 Torr. These Oerlikon Leybold RUVAC WH4400FC Root's blower have an 8” ANSI inlet and are standard industrial Root's blower packages prepared for hydrocarbon vacuum pump oil and driven by water cooled hermetically sealed motors. The WH pumps do not include a pressure differential valve that allows them to be started at the same time as the roughing pump. Therefore, a cut-in and cut-out circuit must be supplied to turn the blower on or off dependent on the systems vacuum pressure. The pressure differential and compression ratio between the intake and discharge sides of a are limited on WH series Roots pumps. If the allowable pressure differential is exceeded, the pump overheats or the motor is overloaded. In practice, the maximum attainable pressure differential is recommended to be 7.5 Torr. We therefore recommend a Blower cut-in and cut-out circuit which does not turn on the blower to below 7.5 Torr and will turn off power to the blower when the system pressure rises above 7.5 Torr. The SOGEVAC SV630BF backing pump is water cooled, has built-in oil mist filtration system with integrated oil return, and has a 444 cfm roughing speed. These Oerlikon Leybold RUTA vacuum pump packages have 8” ANSI inlet flange, 4” ANSI exhaust flange, requires 27 liters of vacuum pump oil, weigh approximately 2,932 lbs, and operates on 3-Phase 440-480 VAC input power.