PROBEST Dissolved Oxygen Sensor Calibration: Complete Step-by-Step Guide

Complete PROBEST Dissolved Oxygen Sensor calibration guide: zero calibration with sodium sulfite, auto air calibration, step-by-step menu operation, troubleshooting, and best practices for accurate water quality monitoring.

Introduction

Accurate dissolved oxygen (DO) measurement is critical for wastewater treatment, aquaculture, environmental monitoring, and industrial water processes. The PROBEST Dissolved Oxygen Sensor delivers reliable performance—but regular calibration is essential to maintain precision, correct sensor drift, and ensure data compliance.

This guide covers the full two-point calibration (zero calibration + air calibration) procedure for PROBEST DO sensors. Following these steps will ensure stable, accurate readings and extend your sensor’s service life.

Why Calibrate Your PROBEST DO Sensor?

Eliminates drift: Corrects zero-point and slope errors from aging, fouling, or environmental changes.

Guarantees accuracy: Aligns readings with known 0% and 100% oxygen standards.

Maintains compliance: Meets regulatory requirements for water quality monitoring.

Reduces downtime: Prevents costly process errors from bad data.

Recommended calibration frequency:

Standard environments: Every 1–3 months

Wastewater/high-fouling: Every 2–4 weeks

After maintenance: Immediately (membrane replacement, repair)

After long storage: Before reuse

Part 1: Zero Calibration (0% Oxygen)

Zero calibration establishes the sensor’s baseline in an oxygen-free environment.

What You Need

PROBEST DO sensor & transmitter

Tap water

Anhydrous sodium sulfite powder (oxygen scavenger)

Beaker, stirring rod

Clean paper towels

Step-by-Step Zero Calibration

Prepare deoxygenated water

Fill a beaker with clean tap water.

Add anhydrous sodium sulfite powder (≈2–3% concentration).

Stir vigorously until fully dissolved.

Let stand 5 minutes to ensure complete deoxygenation.

Sensor preparation

Clean the probe tip with water; remove debris or biofilm.

Fully immerse the sensor in the deoxygenated water.

Soak for 10 minutes to stabilize.

Transmitter menu operation

Press the menu button to enter the interface.

Select the dissolved oxygen channel → press OK.

Navigate to Calibration → select Zero Calibration.

Screen: “Wait 15 seconds” → press OK.

After 15s: “Wait 6 seconds” → wait for countdown → press OK.

Display confirms: Zero Calibration Successful.

Part 2: Auto Air Calibration (100% Saturation)

Air calibration sets the full-scale (100% oxygen) reference using ambient air.

Step-by-Step Air Calibration

Prepare the sensor

Remove the sensor from the zero solution.

Wipe the probe tip completely dry with a clean paper towel.

Place the sensor in still, room-temperature air (avoid direct sun/drafts).

Transmitter menu operation

Re-enter the menu → select the DO channel.

Go to Calibration → choose Auto Air Calibration → press OK.

Screen: “Wait 15 seconds” → wait for reading stabilization.

Press OK → wait for secondary stabilization → press OK again.

Display confirms: Calibration Successful.

Return to the main measurement screen.

Post-calibration verification

Compare readings with a dissolved oxygen-temperature reference table.

Confirm values are within ±0.2 mg/L of expected saturation.

Pro Tips for Perfect Calibration

✅ Order matters: Always perform zero calibration first, then air calibration.

✅ Stability time: Allow full stabilization (10 min zero, 5–15 min air) for best accuracy.

✅ Environment: Calibrate at stable temperature (±1°C) and normal atmospheric pressure.

✅ Cleanliness: Keep the probe clean; avoid touching the membrane with fingers.

Troubleshooting Common Issues

Unstable readings:

Clean the membrane; check for bubbles or fouling.

Ensure full stabilization time.

Calibration fails:

Verify fresh sodium sulfite; prepare new zero solution.

Check for damaged membrane or depleted electrolyte.

Deviation after calibration:

Repeat full two-point calibration.

Confirm temperature compensation is active.

Conclusion

Regular zero and air calibration is the foundation of reliable PROBEST Dissolved Oxygen Sensor performance. By following this standardized procedure, you ensure accurate, compliant data for wastewater treatment, aquaculture, and environmental monitoring applications.

For service, support, or replacement parts, contact the PROBEST technical team.