1. Introduction

This document provides detailed calibration procedures for the Oxygen Detector (OLCT) to ensure accurate measurement and reliable performance. Follow the instructions carefully to avoid operational errors.

2. Equipment Required

• Multimeter (for current measurement)
• Nitrogen (N₂) gas cylinder (for zero calibration)
• Minus (-) screwdriver

3. Current (mA) Connection Setup

1. Disconnect one signal cable from the terminal block.
2. Connect the multimeter probes between the terminal block and the disconnected cable.
3. Wait for the oxygen detector to stabilize until it transmits the normal current (mA).
   • ⚠️ Note: When reconnecting the cable, the current will initially display 2.0 mA, then gradually increase to match atmospheric values. It will stabilize to the normal condition within 5 to 10 minutes.

4. Zero Calibration Procedure

1. Turn the selector valve to Calibration Mode on the control cabinet.
2. Supply Nitrogen (N₂) gas to the oxygen sensor through the calibration connector until stabilization is achieved.
3. Adjust the output current to 3.86 mA (0.0%) using the Zero Potentiometer on the O₂ sensor.
4. If the display does not read 0%, remove the O₂ detector cover and adjust to 0% (4 mA) using a minus (-) screwdriver.

⚠️ Caution: Ensure the N₂ gas flow is stable before performing adjustments to avoid inaccurate calibration.

5. Span Calibration Procedure

1. Disconnect the input/output tubes from the oxygen detector then unscrew the sampling cap to allow fresh air to flow freely and expose it to the atmosphere.
2. Observe the output current (mA) as it gradually increases.
3. Confirm the oxygen concentration on the monitor reads approximately 20.9%.
4. If the concentration is incorrect, adjust the output current to 15.05 mA (20.9%) using the Span Potentiometer on the O₂ sensor.

⚠️ Important: The O₂ sensor must be calibrated at 20.9% oxygen concentration in a fresh atmospheric environment.

6. Output Current Reference Table