4 Biggest Mistakes in Instrumentation

Despite ongoing advancements in measurement and communications technology, instrumenting a process for feedback control remains a technical challenge. Today’s sensors are certainly more sophisticated than ever
before, and fieldbus technology has simplified  many installation issues considerably. Nonetheless, much can still go wrong with an instrumentation project.
Mistake #1:
Selecting the wrong sensor
Technology mismatch Although it’s generally obvious what quantity needs to be measured in a flow, temperature, or pressure control application, it’s not always obvious what kind of flow meter, temperature sensor, or pressure gauge is best suited to the job. A mismatch between the sensing technology and the material to be sensed can lead to skewed measurements and severely degraded control.

Mistake #2:
Installing sensors incorrectly
The best sensor can yield disappointing results if not installed correctly. Magmeters, for example, tend to generate noisy signals if the flow they’re measuring is turbulent. Bends, junctions, and valves in a pipe can all cause turbulence, thus magmeters work best when installed in sections of straight pipe. Temperature sensors are also sensitive to placement. Even a highly accurate RTD tucked in the corner of a mixing chamber will
only be able to detect the temperature of its immediate vicinity. If the mixing of the material in the chamber
is incomplete, that local temperature may or may not represent the temperature of the material elsewhere in the chamber.
Mistake #3:
Generating gibberish--Noise
Ground loops are not the only source of noise that can distort a sensor’s readings. Radio frequency interference (RFI) is even more common in plants that use walkietalkies, pagers, and wireless networks extensively. RFI also results whenever a current changes, such as when an electromechanical contact or a static discharge generates a spark.
Mistake #4:
Quitting too soon Even when the data filters are in place and the last loop has been tuned, the project isn’t over. There are some commonly neglected chores that should continue as long as the instrumentation system
is in place.

Taken from this: full paper :