Glossary · Sensors and measurement
Measuring instrument
Also known as: Measuring device, Instrument
German: Messgerät
In metrology, a measuring instrument is a device used for making measurements, alone or in conjunction with one or more supplementary devices. In process plants, the term covers field instruments such as transmitters, analyzers and indicators.
- Sensors
- Standards
In one sentence
A measuring instrument is a device used to make measurements, alone or with supplementary devices, from a caliper to a process transmitter.
Example
Each measuring instrument in the plant carries a tag number that links it to its entry in the instrument index and its calibration history.
How it applies
- Engineering: A measuring instrument can be a single device or part of a measuring system with sensor, transmitter and indicator. Its specification includes measuring range, error limits, environmental conditions and interfaces.
- Quality: Instruments used for product or safety decisions are managed as inspection equipment: identified, calibrated at defined intervals and protected against unauthorized adjustment.
- Maintenance: Calibration status and history belong to the instrument, identified by tag and serial number. A replacement instrument needs its own calibration record.
- Documentation: Use tag numbers consistently in P&IDs, the Instrument index, circuit diagrams and manuals, so the same instrument can be traced through all documents.
Measuring instrument vs. sensor
A Sensor is the element that responds to the measured quantity. A measuring instrument includes the sensor and delivers a measured value, for example on a display or as a standardized signal.