How to Keep Your Gas Detector Reading Accurately

Stay Informed

Are you in the market for a new gas detector? You may wonder if you can use the same calibration gas that you’ve been using for the detectors you are replacing or phasing out. Usually, the answer is “no.” The gas values used for older models, even if by the same manufacturer, don’t often match the gas values required for new units. Even if two gas detectors have identical sensors and features, the calibration gas values needed may be completely different.

Comparing Gas Concentration Values

Let’s compare calibration gas for two standard four-gas models. “Standard four-gas” means that each unit has oxygen, LEL, carbon monoxide, and hydrogen sulfide sensors. The majority of multi-gas detectors sold on the market today have this four-gas configuration. To compare, let’s look at two standard four-gas meters.

Unit A uses a calibration gas mixture of: 
  • 18% oxygen
  • 50% LEL methane
  • 50 ppm carbon monoxide
  • 25 ppm hydrogen sulfide
Unit B uses a calibration gas mixture of: 
  • 15% oxygen
  • 25% LEL pentane
  • 100 ppm carbon monoxide
  • 20 ppm hydrogen sulfide

As the comparison shows, even though the two units have an identical sensor configuration, they each require a different set of gas concentration values. 

Matching Manufacturer Requirements

A gas detector must be calibrated with the correct gas values for which it is set up. If it’s calibrated with incorrect values, the sensors will not respond accurately. This creates a potentially dangerous situation for personnel using the gas detector.

Furthermore, the regulators used to release gas from the cylinders also have specific flow rates. These rates need to match the requirements set by the manufacturer. Flow rates are usually measured in liters per minute and will differ from part number to part number.

Manual vs. Automatic Flow

A regulator can be manual flow or automatic demand flow. Manual flow means the regulator has a valve on its side that is manually opened and closed. This valve is turned one way to release the flow of gas and the opposite way to shut it off.

A manual flow regulator is almost never used with a docking station or automatic calibration station. Docking stations generally require an automatic demand flow regulator. Rather than a manual “on/off” valve, these regulators must have a pump in the gas detector, on the gas detector or in a docking station.

Determining Accurate Calibration

To summarize, never presume gas detectors will use the same calibration gas values just because the units have the same sensor configuration. Gas detectors with the same sensor configuration can quite possibly require gas concentration values and regulator flow rates that are completely different. 

Need more information? Contact WESCO today.