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