Got Gas? The Gas Ballast Valve
The gas ballast valve is a convenient and simple device that can extend pump life in vacuum pump systems that accumulate amounts of water and/or condensing vapors in the oil(condensate). The condensed vapors destroy the beneficial properties of the oil, sabotaging the functions that the lubricant contributes to pump operation and longevity. Using the gas ballast valve allows the atmosphere to enter the pump on the compression side just prior to the exhaust ports. That atmosphere is at a much lower concentration of vapor than what is in the pump so it reduces the relative vapor constituent of the gas in that area just prior to the exhaust. The mix of atmospheric gas and pump gas immediately vents to the exhaust so is expelled as vapor and does not re-condense back into the oil. This vapor dilution cycle, over time (usually hours to overnight), evacuates the condensate, converted to vapor, as the oil is cycled around the internal workings of the pump at low pressure. The oil, now free from condensate contamination, can resume its many functions and contribute to proper pump operation. There is a practical limit to the amount of condensate that can be removed using the gas ballast so if the oil is heavily
laden with contaminant the only option would be to change out the oil.
With an oil sealed pump, understanding the function of and using the gas ballast will extend pump life. Many operations use a solenoid controlled gas ballast valve and program the valve to open during some portion of the pumping cycle to have an intermittent vapor evacuation in the process. We have found, counter-intuitively, that opening the gas ballast valve minimally so there is a very slight amount of
atmosphere entering the pump often improves the vacuum if the system has a large concentration of condensate or the atmosphere in the process chamber generates contaminant vapors into the oil. In every case keeping the oil clean is essential.
VP of Engineering