Applications & Measurements

Effective vacuum is about balance, not maximum pressure

Industrial vacuum level is measured either as absolute pressure (starting from perfect vacuum) or relative pressure compared to atmospheric pressure. In gripping applications, holding force depends on the pressure differential between the suction cup and ambient air. 

Optimal vacuum levels typically range from 30% for high-flow systems to 80% for airtight circuits, balancing energy consumption, response time, and holding stability.

MEASURING VACUUM LEVEL

Scientists use absolute pressure, with a scale that starts at perfect vacuum, with atmospheric pressure measuring roughly 1 bar.

For industrial applications, relative pressure is preferred because it marks a clear distinction between vacuum (negative pressure) and positive pressure. In gripping applications, vacuum is only effective by its difference compared with atmospheric pressure. However, atmospheric pressure varies slightly depending on the altitude of the application site. This is why it is more practical to express vacuum level as a percentage of the atmospheric pressure.

The scale shown on the right illustrates the relationship between pressures expressed in bar and mbar and the vacuum level shown as a percentage of the atmospheric pressure. This relationship is accurate for use at an altitude of 100m. This is the measurement that we will use when discussing suction cups, since this is the most common altitude of industrial sites

RECOMMENDED VACUUM LEVELS

Gripping provides a level of effort that is proportional to the level of the vacuum that generates it (see curves below). For the most efficient operation, a maximum vacuum level is recommended. However, the curves also show that a high level of vacuum:

  • has a high energy cost
  • takes a long time to establish

This is why the vacuum levels used should be limited, from 30% when a high fl ow of vacuum needs to be maintained, to 80% in an airtight circuit (no fl ow required to maintain the vacuum).