Short answer: 
A bump test checks that your gas detector responds to gas and activates its alarms.
A calibration confirms the accuracy of the detector’s measurement and adjusts it to a certified standard.

Both procedures are essential for safe, compliant operation in New Zealand workplaces.

What Is a Gas Detector Bump Test?

A bump test is defined as:

“A brief exposure to a known concentration of gases for the purpose of verifying sensor and alarm operation.”

In practical terms, it’s a fast go/no-go check that confirms your detector will:

• detect gas

• respond within the required time

• activate alarms

• keep workers safe

A bump test does not confirm whether the detector is accurate — only whether it is functioning correctly at that moment.

How a Bump Test Works (Including the Key Industry Threshold)

During a bump test:

1. The detector is exposed to a known concentration of gas.

2. It must trigger both audible and visual alarms.

3. It must reach at least 50% of the target alarm level within 45 seconds
   – a commonly used benchmark for many professional gas detection systems.

4. If it fails to reach this threshold, a fail report is generated.

What a Fail Report Means

A failed bump test is a critical red flag.

It means the detector:

• may have degraded sensors

• may be unresponsive

• is not safe for use
  

The detector must be removed from service immediately and booked for full calibration.

How Often Should You Bump Test?

Best practice is:

• Daily

• Or immediately before each use
  

This aligns with common requirements across global safety standards and typical WorkSafe NZ expectations.

Automated Docking Stations

Modern docking stations make bump testing extremely efficient:

• automatic gas application

• pass/fail logging

• traceable compliance records

• reduced user error
  

They provide a complete audit trail, which is particularly valuable for regulated NZ industries such as confined space entry, wastewater, energy, manufacturing, and hazardous substance handling.

What Is Gas Detector Calibration?

Calibration is a more detailed process than bump testing.
It involves:

1. Testing the detector against a certified calibration gas.

2. Adjusting the sensor output to correct any deviation.

Where a bump test verifies function, calibration verifies accuracy.

A properly calibrated detector gives you confidence that:

• 50 ppm on the screen actually is 50 ppm

• alarm setpoints are trustworthy

• readings comply with manufacturer tolerances

• the detector isn’t drifting due to age, humidity, or environmental exposure

How Calibration Works

Calibration typically includes:

1. Applying a Known Gas Concentration

For example, applying a certified gas mixture of 50 ppm.

2. Comparing Real Reading vs. Displayed Reading

If the reading is outside the acceptable tolerance range — often ±10% — adjustment is required.

3. Adjusting Sensor Output

The detector’s electronics are tuned until the display matches the certified gas.

This restores the detector’s true-to-value measurement accuracy.

How Often Should Calibration Be Performed?

Calibration frequency depends on:

• manufacturer recommendations

• type of gas sensor

• environmental conditions

• operating environment (e.g., confined space, wastewater, H₂S-heavy areas)

• usage frequency

Typical calibration cycle:

Every 1-6 months

You must also calibrate:

• after a failed bump test

• after long storage

• after harsh environmental exposure

If you’re unsure, follow manufacturer guidance or consult an NZ gas detection specialist.

Do You Need Both?

Yes. They work together:

• Bump test: Will it warn me today?

• Calibration: Are the numbers accurate?
  

Skipping either introduces avoidable risk.

Manual vs Automated Testing

Manual Testing

You can bump test a detector manually by applying gas from a calibration cylinder. This is effective but relies on user skill and thorough documentation.

Automated Docking Stations

Automated systems:

• apply gas consistently

• verify response time

• store pass/fail history

• notify you of missed maintenance

• streamline compliance documentation

• reduce downtime
  

These systems are now considered best practice in many NZ industries.

Final Takeaway

• Bump tests ensure your detector responds when exposed to gas.

• Calibration ensures your detector reads accurately.

• Both are essential for safe operation and workplace compliance.

• A failed bump test requires immediate calibration.

If your workplace relies on gas monitoring, consistent testing isn’t optional — it’s essential for keeping your team safe and your equipment compliant.

Need advice or service?

Contact New Zealand’s gas detection experts at Entec for further advice, or to discuss your detailed requirements, or phone us on +64 9 277-2211. We’re here to help.