Vacuum Pumps Installing a Variable Velocity Drive (VSD), sometimes called a adjustable frequency drive, usually saves between 50 and 65% in electricity costs with the same or better regulation of vacuum. The number of energy savings could be from 30 to 80 percent. They could be adapted to blower or in some instances rotary vane type vacuum pumps. They work by changing the swiftness of the vacuum pump predicated on the reading from a pressure sensor that is installed on the vacuum line near the receiver jar. The VSD is basically a dedicated computer with many adjustments therefore it could be possible to improve vacuum regulation over the typical pneumatic vacuum regulator that only includes a vacuum level Energy-Conserving Vacuum Pump adjustment. A VSD for a vacuum pump is usually cost-effective for a dairy that milks a total of 8 hours or even more each day. Typically a VSD will not be a cost-effective option for small dairies because of less milking period and therefore shorter vacuum pump operate times but there are several other choices to save energy costs.