Chapter 3. Measurement Methods and Control Strategies
Measurement methods for automation are somewhat different from those designed for use in laboratories and test centers.
Specific to automation, measurement methods that work well in a laboratory might not work at all in a process or factory-floor environment. It might not be possible to know all the variables acting on a measurement to determine the degree of error (uncertainty) of that measurement. For example, a flowmeter may be calibrated at the factory with an accuracy of ±0.05% of actual flow. Yet in the field, once installed, an automation professional might be lucky to be able to calibrate the flowmeter to ±10% of actual flow because of the conditions of installation. ...