To calibrate a pressure switch using a dry block calibrator, you need to follow a methodical procedure that ensures accurate calibration. Here’s a step-by-step guide to calibrate the pressure switch:

What You’ll Need:

• Dry Block Calibrator (with a pressure generation feature or coupled with a pressure source like a hand pump)

• Pressure Switch

• Reference Pressure Gauge (for comparing the applied pressure)

• Calibrated Multimeter (if the pressure switch is electrical)

• Tools for adjusting the pressure switch (usually a screwdriver for setpoint adjustment)

• Temperature Probe (if your dry block calibrator requires temperature control)

Steps for Calibration:

1. Prepare the Equipment:

• Ensure the dry block calibrator is set up and functioning correctly. It should be able to apply a stable pressure to the system.

• Connect the pressure switch to the dry block calibrator and reference pressure gauge.

2. Set the Dry Block Calibrator:

• If the dry block calibrator has a pressure function, set it to the initial pressure value you want to calibrate.

• If you are using a hand pump or other external pressure source, use the dry block calibrator to heat or stabilize the environment as needed.

3. Adjust the Pressure Switch Setpoints:

• Zero Calibration (Optional): Before starting calibration, you may need to zero the pressure switch. Follow the manufacturer’s instructions for the proper procedure, which could involve adjusting a zero screw or using software.

• Set the First Pressure Point: For example, if the switch has a setpoint of 10 psi, adjust the dry block calibrator to 10 psi (or use your hand pump to set the pressure if using a separate source).

4. Apply Pressure and Monitor Output:

• Slowly increase the pressure on the calibrator and monitor the pressure switch’s output. If the switch is electronic, measure the output with a multimeter (voltage, current, or resistance).

• Compare the actual setpoint with the reference gauge to ensure that the pressure switch activates or deactivates at the correct setpoint.

5. Adjust the Setpoint:

• If the switch does not activate at the correct pressure, use the adjustment screw or software interface (depending on the switch type) to change the setpoint.

• If the switch has a hysteresis or differential setting, check both the "turn-on" and "turn-off" pressures.

6. Test Multiple Points:

• After adjusting, test at different points across the full range of the pressure switch to ensure it activates correctly at each setpoint.

• Apply pressures at various intervals (e.g., 25%, 50%, 75%, and 100% of the maximum range) and verify that the switch operates within the desired range.

7. Final Verification:

• Once you’ve calibrated the switch at multiple points, verify that the output is consistent and within specifications.

• Perform a final check for accuracy, and ensure the pressure switch behaves as expected across the entire range.

8. Record Calibration Results:

• Document all calibration results, including pressures at which the switch activated and the corresponding output values. If required, generate a calibration certificate for your records.

Key Tips:

• Take your time: Pressure switches are sensitive, so make sure you apply pressure slowly and allow the system to stabilize before taking measurements.

• Use high-quality reference gauges: For accurate calibration, use well-calibrated and accurate pressure gauges.

• Safety: Always ensure that the system is set up safely and that the pressure limits of the switch and the calibrator are respected.