01
Hysteresis: definition and engineering context
Directional response difference. Difference in output depending on whether the input approaches from above or below.
The term belongs to the measurement & control context. Its exact limits can depend on the cited standard, catalog convention, unit system, reference state, and component configuration.
02
Why Hysteresis affects pneumatic selection
Relevant to regulators, sensors, proportional devices, and repeatability.
- Repeatability: Do not confuse it with absolute accuracy.
- Response time: Include valve, tubing, load, pressure, and sensor delays in cycle estimates.
- A: Use the rod-side annular area for retract force, not the full bore area.
- Bore: Force rises with the square of bore diameter.
03
How to evaluate Hysteresis in a catalog or replacement project
Read the value together with its unit, test basis, operating pressure, temperature, circuit state, and manufacturer definition.
For replacement work, compare the complete datasheet and drawing. A matching abbreviation or nominal size does not by itself prove functional or dimensional interchangeability.
- Repeat output consistency: Closeness of repeated results under the same conditions.
- Actuation response interval: Time between an input change and a defined output response.
- Effective piston area: Pressurized piston area used in the theoretical force calculation.
- Cylinder bore diameter: Inside diameter associated with piston area.
Selection checklist
What to verify before selection
- 01
Relevant to regulators, sensors, proportional devices, and repeatability.
- 02
Do not confuse it with absolute accuracy.
- 03
Include valve, tubing, load, pressure, and sensor delays in cycle estimates.
- 04
Use the rod-side annular area for retract force, not the full bore area.
Application caution
Common mistakes
- Treating Hysteresis as a universal definition without checking the manufacturer or standard context
- Mixing gauge and absolute values, incompatible units, or different reference conditions in one comparison
- Selecting a component from the term or nominal value alone without checking the complete operating point and drawing
FAQ