The auto-calibration system allows the user to remotely and automatically calibrate the methane and carbon dioxide concentration sensors. For the auto-calibration, two compressed gas tanks are needed – a zero gas tank and a span gas tank. Special gas regulators are connected to the gas cylinders and a sample line from each tank is plumbed to the gas sensor boxes. The system is configured to periodically draw gas first from the zero tank, then from the span tank. Typically this calibration is automatically performed once per day.
The advantage of the auto-calibration system is that calibrations can be performed regularly which usually increases the precision and accuracy of the measurements. The auto-calibration system is also more convenient. Without auto-calibration, a person is required to travel to the system on a regular basis and manually calibrate the system which usually requires about 15 minutes of time once per week.
The auto-calibration system includes two gas regulators, tubing, two solenoids, and controls inside the gas sampling unit.