Vacuum Pumps – The installation of a Variable Speed Drive (VSD), sometimes called a variable frequency drive, usually saves between 50 and 65% in electricity costs with the same or better regulation of vacuum. The range of energy savings can be from 30 to 80 percent. They can be adapted to blower or in some cases rotary vane type vacuum pumps. They work by changing the speed of the vacuum pump based on the reading from a pressure sensor that is mounted on the vacuum line near the receiver jar.
The VSD is basically a dedicated computer with many adjustments so it may be possible to improve vacuum regulation over the typical pneumatic vacuum regulator that only has a vacuum level adjustment. A VSD for a vacuum pump is usually economical for a dairy that milks a total of 8 hours or more per day. Typically a VSD will not be an economical option for small dairies due to less milking time and thus shorter vacuum pump run times but there are some other options to save energy costs.
Check to see that your current vacuum pump is not oversized. It wasn’t too many years ago that the thought was that more vacuum pump capacity was better. Research has since shown that if the vacuum pump is sized at 3 cubic feet per minute (cfm) per milking unit plus a 35 cfm base capacity for up to 32 milking units to account for a milking unit falloff is usually adequate. Checking to make sure your vacuum pump is not grossly oversized is a good start. If your current vacuum pump has larger capacity than needed, it may be possible to change belts and pulleys to slow the pump down. Keeping drive belts in good condition and tight will also reduce electricity usage.
- Refer to UW Extension bulletin A3784-05: “Energy Conservation in Agriculture: Vacuum Systems“.
- “Sizing vacuum pumps for milking“, G.A.Mein et. al., National Mastitis Council Annual Meeting Proceedings, 1994.
- “Sizing Vacuum Pumps for Cleaning Milking Systems“, D.J.Reinemann & G.A.Mein, National Mastitis Council Annual Meeting Proceedings, 1995.
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