An improved controller for mercury diffusion pumps

A mercury diffusion pump and rotary pump controller has been constructed to minimize the hazards associated with such pumps. The controller removes power from the diffusion pump when (1) cooling water flow is insufficient, and (2) pressure in the vacuum system is higher than a process control set point. To prevent problems associated with breaks in the vacuum line or breakage of the rotary pump V‐belt, the power to both the diffusion pump and rotary pump is removed and an audio alarm sounded if the system pressure exceeds process control set point for more than approximately 50 s.