Vacuum Generator Selection

Vacuum generators of different product lines

The selection of the matching vacuum generator (ejector, pump or blower) is determined by several factors:

  • Type of workpiece: porous, air-tight
  • Energy supply options: a lower case electricity, compressed air
  • Restrictions for size and weight
  • Maintaining  cycle times:
    Short cycle times: Ejector
    Long transport distances: Pump or blower

Suction rate of vacuum generator

The diameter of the suction cup determines the suction rate that a vacuum generator has to apply to evacuate the suction cup. Based on experience and measurements with system designs, we recommend a selection based on the following table:

Suction capacity as a function of suction cap diameter

Suction-cap Ø Suction capacity VS
Up to 60 mm0.5 m3/h 8.3 l/min
Up to 120 mm1.0 m3/h16.6 l/min
Up to 215 mm2.0 m3/h33.3 l/min
Up to 450 mm4.0 m3/h66.6 l/min

The specified values apply regardless of the type of vacuum generation. The recommended suction ratio applies per suction cap and only for smooth, air-tight surfaces. For porous, permeable workpieces we recommend conducting a corresponding suction trial with the original workpiece.

Calculation of the suction rate V [m3/h, l/min], that the vacuum generator has to apply

V = n x VS

n = Number of suction caps
V= Required suction rate for an individual suction cap [m3/h, l/min]


V = 6 x 16,6 l/min
V = 99,6 l/min

For this example we choose:

Compact ejectors SCPi 20 with a suction rate of 140 l/min. The compact ejector offers valves for control of the “suction” and “blow off” functions as well as system monitoring for ensuring process safety during handling. The compact ejector SCPi is also equipped with IO-Link Technology. It makes the various diagnostic functions visible and usable on the control level. This increases system availability and makes automation processes even more efficient.