How the Pick Up Velocity Control works
On the Smart Distribution System the controller contains information about specifically material is being conveyed and the line size feeding the vacuum receiver. Add a VFD to your vacuum pump and you can have a system that controls the velocity at the pick-up point.
How the pick up velocity control works:
The system looks at the vacuum level at the pump and calculates the pick-up velocity. The system then adjusts the speed of the pump to obtain and maintain the optimum pick-up velocity.
A Real World Example:
System specifics:
- 250 feet horizontal
- 40 feet vertical
- Qty (3) 90 degree bends
- 2.5" convey line (tubing)
- Conventional system designed for pick-up velocity of 4,000 fpm (120 cfm at the pick-up point).
Roots 36 URAI or equivalent spinning at 2,700 fpm and 12" Hg will accomplish this. Following are some of the convey calculations for this system:
- Convey Rate = 2,130 pph
- HP Consumed = 7.5 hp
- Convey efficiency (pph/hp) = 284
- RPMs = 2,700
- Pick-up Velocity = 4,000 fpm
Now what happens to this system when a draw happens with less than 12" Hg of loss. The following assumes a draw with 8" Hg loss. This is a very typical convey loss.
Conventional System Calculations
- Convey Rate = 492 pph
- HP consumed = 4.9 hp
- Convey efficiency (pph/hp) = 100
- RPMs = 2,700
- Pick-up Velocity = 5,275 fpm
Speed Controlled System Calculations
- Convey Rate = 1,284 pph
- HP consumed = 3.8 hp
- Convey efficiency (pph/hp) = 338
- RPMs = 2,150
- Pick-up Velocity = 4,000 fpm
