Cut-in pressure, cut-out pressure and differential
The compressor may start when pressure falls to the lower limit and stop when the upper limit is reached. The difference is hysteresis. A narrow band can cause more starts; a wide band affects minimum consumer pressure and energy use. The adjustment method depends on the specific equipment.
Settings must be considered in the context of the complete package
Assessment covers the maximum allowable pressures of the compressor, receiver and accessories, demand requirements and starting limits. Air receiver volume and flow affect the time between starts. Frequent switching may be caused by a leak, insufficient storage or a fault; simply changing the pressure may not help.
What to check in practice
- Verify actual switching limits and measurement calibration.
- Assess the allowable pressures of all package components before making changes.
- Check the number of starts, demand and network tightness.
Example scenario
In an example band of 6 to 8 bar(g), the source begins replenishing at 6 bar(g). If the consumer needs 6 bar(g) and the loss between it and the receiver is 0.4 bar, the lower limit is insufficient. The solution requires assessing losses and allowable settings, not blindly raising the upper pressure.
What to watch out for
- Using a pressure switch as a safety device against overpressure.
- Raising pressure above the equipment's design limit.
- Confusing the outlet regulator with compressor control.
Can I adjust the pressure switch myself using online instructions?
The procedure must suit the particular switch and the entire package. The work may involve electrical and pressure hazards. Do not perform it without qualifications and documentation; a service technician will also identify the actual cause of unsatisfactory operation.