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G7c/G7x Troubleshooting: Sensor Drift and Cross-Contamination

G7c/G7x Troubleshooting: Sensor Drift and Cross Contamination

Updated: May 11, 2023

This article outlines troubleshooting steps you can perform if you are experiencing issues with sensor drift or cross contamination issues for G7c/G7x devices.

Should the troubleshooting below not resolve the issue, please contact Technical Support.

Sensor Drift

Sensor drift refers to changes in sensor readings due to various environmental factors such as temperature, humidity, and other external elements.

Blackline portable and area monitoring devices are rated to operate in weather conditions between -20°C (-4°F) and 55°C (131°F). Devices will function in temperatures colder or hotter than this for short periods of time, but Blackline Safety does not recommend letting the device’s internal temperature drop below -20°C (-4°F) or rise above 55°C (131°F).

Shocking an electrochemical sensor (CO, H2S, O2) from room temperature to extreme cold and vice versa can cause temporary drifts in sensor readings. These readings typically resolve in less than a minute. Very hot and dry conditions can destroy electrochemical sensors by causing the electrolyte to dry out.

Similarly, shocking an IR sensor (LEL) from room temperature to an extremely cold environment can cause the sensor to drift slightly for a short period of time (on an LEL-IR sensor, the reading should typically be < 10% LEL).

Performing a Calibration if the Sensor does not Automatically Re-establish a Baseline

  1. Place G7 into G7 Dock.
  2. Close the lid until it clicks into place.
    If your G7 device is overdue for calibration, it will automatically begin calibrating when placed into G7 Dock. If not, proceed to the next step.
  3. Use G7’s arrow buttons to navigate to Calibration, then press the OK button.
    G7 Dock performs the calibration.
G7 indicates whether the calibration has passed or failed and when it is ready to be removed from G7 Dock.

Troubleshooting a Failed Calibration

  1. Relocate to a fresh air environment.
  2. On your G7, press the OK button to open the main menu.
  3. Using the up and down buttons, scroll through the menu, then select Gas Options by pressing the OK button.
    The Gas info menu opens.
  4. Using the up and down arrow buttons, scroll through the menu, then select Zero sensors by pressing the OK button.
  5. To continue, select Yes by pressing the up arrow button. Do not apply any gas.
    By default, G7 zeroes all sensors.
  6. When zeroing is complete, press the OK button to return to the Gas info menu.
    Important:

    If you see a zero incomplete message on your screen you may be in an environment with gas levels, or your cartridge may need to be calibrated.

If you see Zero incomplete display on your device, perform a calibration as outlined previously. If the issue persists, contact Blackline Safety Technical Support.

Cross Contamination

Gas sensors are susceptible to contamination by a variety of common cleaning chemicals. For more information, including a list of chemicals you cannot use to clean Blackline Safety devices, see Cleaning Devices and AccessoriesNo Content found for /db/organizations/blacklinesafety/repositories/production/content/documents/G7c_x_G7_Bridge/Internal_DSC_Procedures/G7c_Troubleshooting_and_Maintenance_Guide_-_DSC_Project_R3_TO_BE_VERIFIED/cleaning_devices_and_accessories.dita.

If a device is exposed to the chemicals listed in the support article or any new chemical or compound, a gas reading displays on the LCD while in a fresh air environment (e.g., 65 ppm CO in a clean air environment).

If you suspect a CO sensor may be contaminated, calibrate the device to ensure the sensors function properly.

Troubleshooting a Failed Calibration with a Persistent Reading

  1. Ensure the device is powered on.
  2. Plug the device into the charger and confirm the red LED is illuminated.
  3. Leave the device powered on and plugged into the charger until the CO reading drops below 5 ppm. The duration required depends on the severity of contamination.
  4. When the reading is below 5 ppm, perform a calibration.

To prevent future contamination, avoid direct contact with chemicals.

Note: The steps mentioned above are intended for contaminated sensors reading less than 100 ppm. If the CO sensor displays a reading greater than 100 ppm or displays Overlimit, contact Blackline Safety Technical Support.
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Last updated: April 14, 2026