Slow Pump Valves are two position high vacuum pneumatic valves that reduce turbulence within a vacuum system. By opening the by-pass valve first, a slow pumping is achieved. Once the system reaches a determined vacuum level, the parent valve is opened allowing full pumping speed. SPV valves feature removable orifices to allow flexibility. The SPV valve series is intended to control a pump down cycle that is virtually turbulence free to sensitive vacuum systems.