Robinair 15400 Vacuum Pump CoolTech Series is a highly dependable 20 micron rated, 2-stage offset rotary vane vacuum pump. The Robinair 15400 features a built-in check valve to prevent oil from flowing back into the system in the event of a power loss, a gas ballast to pump water vapor into the atmosphere instead of letting it accumulate in the oil reservoir, and more.