Gas Detector Calibration

I have been working in industrial safety for a few years now, and one topic that most people still have questions about is gas detector calibration. In this article, I will answer all questions related to this topic.

What is gas detector calibration?

Gas detector calibration exposes a traceable concentration of test gas in a controlled environment with a certified gas from the National Institute of Standards and Technology (NIST).

Types of detector calibration

There are two types of calibrations: manual calibrations and automated calibrations.

Manual calibration

This calibration is performed manually, meaning that it is performed without a docking station.

The advantage of this method is that it does not require extra equipment, which is useful if you have a few instruments.

Automated calibration

This is when you use a docking station to calibrate your gas detector; this method makes it very easy to test your gas detectors.

The disadvantage of this method is that you need to buy a docking station or bump test station, which can add extra cost to your company.

It is probably not worth it if you have few detectors, but it can become a wise investment if you have many gas detectors.

How often should I calibrate my gas detector?

Most manufacturers recommend calibrating the gas detector every 6 to 12 months. The recommended calibration frequency is in the user guide for your specific gas detector.

I recommend calibrating more frequency if one or more conditions are met.

  1. The accuracy is more important to you, the device.
  2. The device is used in extreme environments.
  3. Imminent dangerous applications.
  4. If the local and industry regulations require you to do so.

Who can calibrate my gas detector?

Anyone with little training can perform a calibration, so you can calibrate the unit yourself or send it, and someone can calibrate the instrument.

Yourself

You can calibrate the gas detector with some training or read and follow the manufacturer’s instructions.

You must buy the calibration gas and all the necessary accessories to calibrate the unit. Your instrument’s user guide should contain what you need and the calibration procedure.

Send to a calibration center.

If you do not want to calibrate the unit yourself, you can send it to a calibration center; they should be able to perform the task for you.

Most companies that sell gas detectors also offer calibration services. The easiest way to find out where to send the unit is to call from where you bought it; they can help you.

If you can not contact the vendor or the manufacturer, you can always Google calibration centers near you, and you should be able to find some good calibration centers.

What instruments do I need to calibrate my detector?

Here are the accessories you need to calibrate your gas detector.

Calibration cap

If your gas detector does not have a built-in pump, you will need a calibration cap to calibrate the unit.

This is a small cap that you can put on the top of the gas sensor to ensure that all the applied gas enters the sensor.

Gas cylinder

This cylinder contains the gas you will use to calibrate the unit. Make sure that the gas cylinder contains the same gas as the gas your unit detects, and always use certified gas from the National Institute of Standards and Technology (NIST).

Regulator

regulator

The regulator is used as a gas flow control device during the calibration. It establishes and maintains a constant flow rate determined only by the selected orifice number and independent of the initial pressure drop or changes in the inlet or outlet pressure.

If the gas detector has a built-in pump or you are performing calibration using a docking station, I recommend using a demand flow regulator. For manual calibration, always use the constant flow regulator.

Tubing

This is a tube that connects the regulator and the gas detector.

Optional Docking station

You need a docking station for an automatic bump test, but this is optional since the bump test can be done manually.

If one exists for your monitors, a docking and calibration station could help keep your equipment in one place and make calibration and bump testing more convenient.

A demand flow regulator is also needed for a docking and calibration station.

How do I calibrate my gas detector?

Each unit is calibrated differently. My recommendation is to follow the manufacturer’s user guide.

If there is no user guide, please call the manufacturer’s technical support; they can help you. 

What about Ozone calibration?

It is challenging to find a calibration gas cylinder for Ozone gas. If you have an Ozone detector, you have two options: send the unit to the calibration center (most of them have Ozone gas generators) or buy your own Ozone gas generator.

FAQ: Gas detector calibration

What is detector calibration?

A calibration is a “resetting” of the detector’s response against a known target gas concentration in a synthetic air or nitrogen balance.

This will determine the relationship between the detector’s reading and the component gas concentration of interest.

How is a gas detector calibrated?

Calibrating the monitor means exposing it to a known calibration or test gas concentration for a specific time.

This reading becomes the gas detector’s reference point for future readings. Repeat this process each month to ensure accurate readings.

What is the standard calibration for a gas sensor?

A common standard for passing a bump test is that the instrument must detect 50% of the calibration gas concentration exposed to the gas detector.

How often do gas detectors need to be calibrated?

Calibration is only necessary if bump testing indicates the sensor is out of specification.

Electrochemical sensors drift over time and require bump testing every 3 to 6 months. Calibration is recommended annually if bump testing indicates an out-of-spec sensor.

Conclusion

That’s all you need to know about gas detector calibration. If I missed something, please let me know in the comment section below.

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