What does "zero-based" mean in calibration procedures?

In calibration procedures, "zero-based" refers to the principle that an instrument should read zero when there is no input signal. This is essential for ensuring the accuracy of measurements, as it establishes a baseline from which all other measurements are taken. If an instrument does not read zero under no-load conditions, it can lead to systematic errors in readings and incorrect interpretations of data.

By calibrating to a zero point, the functionality of the instrument is validated, ensuring that all subsequent readings reflect only the measured input rather than any inherent bias or offset present in the instrument itself. The zero-based approach is critical in various applications, including pressure gauges, temperature sensors, and flow meters, to maintain reliability and precision in data collection.

Other choices do not relate directly to the concept of zero-based calibration. For example, calibrating instruments only at the maximum range does not address the baseline measurement requirement, while adjustments based on previous readings are more about routine maintenance than zero calibration. Additionally, ignoring ambient conditions is contrary to good calibration practices, as factors like temperature and pressure can affect instrument accuracy.