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July 14, 2004 03:09 PM

Oil-sealed Liquid Ring Vacuum Pump System Available with Variable Frequency Drive

Michigan City, Ind. – July 15, 2004 – With the launch of the VmaxVFD by Dekker Vacuum Technologies, Inc., CNC routers users can experience considerable cost savings through the energy efficiency of the vacuum pump among various industries including routing, engraving, milling, drilling and polishing. 

Recently, Dekker Vacuum Technologies launched the VmaxVFD liquid ring oil sealed vacuum pump system now available with a variable frequency drive.  The VmaxVFD produces vacuum on a CNC router to hold work pieces on the router tool table.  One of the main advantages of using vacuum is that the work pieces to be machined can be held down without damage or distortion. 

Variable speed technology allows equipment to respond more precisely to different loads and varies motor speed to match changing machine and usage requirements.  The VFD controls the Vmax capacity and automatically controls the desired suction pressure whether the router is working on a large 8’ x 10’ sheet of wood or on smaller, intricate pieces.  By operating at as low as half the horsepower, considerable energy savings can be realized.

A common concern with CNC router users is part slippage due to insufficient flow or vacuum level.  The VmaxVFD provides a consistent vacuum level and operates at about half the horsepower thus reducing part scrap rates and material damage.  Because of the reduced energy consumption, users realize immediate cost savings.

When using conventional across the line starting, inrush current during startup will be six to seven times motor running amps.  Power companies analyze these spikes and their frequency and charge customers for these spikes.  Using a VFD eliminates these spikes by soft starting the equipment. 

More significant power savings can be realized by using the VFD to control the vacuum pump based on demand.  When demand for vacuum decreases, the VFD will reduce the speed of the vacuum pump, which in turn significantly reduces the overall power consumption.

A typical example of a 40HP vacuum pump system running with a VFD yields the following results:

  • In a plant using such a system, let us assume the system would be running at maximum load for only 50% of the time. The VFD would be in operation the rest of the time at maximum turndown, resulting in reduced power consumption of 50%.
  • Assuming the plant would be operating two shifts at 8 hours each, total 16 hours per day; a six-day workweek brings us to 96 hours per week or 4,992 hours per year.

Without a VFD

  • Using normal across the line starting:  Power cost = (HP/motor efficiency) x 0.746 x ($/kWh) x (hours per year)
  • Assume a motor efficiency of 93% and a utility rate of $0.10 per kilowatt-hour.
  • Power cost  = (40/0.93) x 0.746 x ($0.10) x 4,992 = $16,017 annual cost.

Using a VFD:

  • 50% of the time the pump will be operating on maximum load or 40HP. Power cost is 50% of annual cost before VFD or $8,008.
  • The other 50% of the time, using the VFD, the pump would operate at 20HP. Power cost = (20/0.93) x 0.746 x ($0.10) x 2,496 = $4,004.
  • Total annual cost using a VFD is $8,008 $4,004 = $12,012.
  • Power cost savings realized is $16,017 - $12,012 = $4,005 yearly.

If we also consider the power savings resulting from elimination of inrush, savings in power wire sizing and savings on protection equipment, the ROI on a new system with the additional cost of the VFD is one year or less

VFDs are also affordable and easy to install on existing systems and are one of the most cost-effective ways to maximize efficiency and reduce operating costs.

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