Analog meters used with EDL surface sensors provide accurate measurements for many types of surfaces over a wide variety of industries. All EDL instruments and sensors require calibration at some interval depending on the customer's quality system. The defined tolerance for the EDL Analog Meter and Sensor is given below in both tabular and graphical formats. Uncertainty in the measurement is used as it best describes the confidence level for measurement made using the specified equipment. Use linear interpolation to derive the error for points in between the table values. All of the values given assume a normally distributed error and have been derived from the limit of error for operation.1 Factors such as, compensation accuracy, field strength variances, meter ballistics and many other factors contribute to the operational limit of error used to derive the given values. Sensor error has been established through both statistically obtained measurement data and estimated uncertainties for the sensors use and calibration. The uncertainty for the sensor and meter have been combined using the Root Sum Squares Method and represent two standard deviations2 giving an overall measurement confidence level of 95%.

Table 1