40062

The 40062 is a customer field-calibration kit for the CS120/A and CS125 visibility and present weather sensors. The kit consists of a calibration disc, two bungs (or stoppers), and a foam-lined case. The calibration disc comprises a neutral-density (ND) filter media with a ground glass disc mounted in an anodized aluminum frame, which simulates low visibility (below 1 km or 3,280.8 ft) as well as perfect visibility (75 km or 46.6 mi). The foam bungs block the optical paths, allowing verification and/or adjustment of the calibration constants held within the system. The calibration disc is designed to mount in a precise and specific location on the CS120/A or CS125 sensor for ease of use and to ensure consistent results. The foam-lined case protects the disc and ensures the bungs are not compressed, which would compromise the accuracy of the calibration. 

The calibration kit functions by scattering a fixed amount of light from the transmitter toward the detector, thereby simulating scattering aerosols in the sample volume.

Each disc has the calibration extinction coefficient (EXCO) written on it. This is related to visibility by the equation "Visibility in km = 3/EXCO." Typically, the disc simulates a visibility of approximately 150 m (492 ft). The high-grade calibrator has a very low temperature coefficient.

The CS120/A and CS125 command structures allow a recalibration in the field, but typically only a simple check is required. 

The calibrators are calibrated against a master disc at Campbell Scientific. This, in turn, has been calibrated against a standard visibility sensor.

In addition, the calibrator comes with two calibration bungs. These are put into the sensor hoods to completely block all light reaching the detector, thereby simulating a perfectly clear atmosphere.