ISA Certified Control Systems Technician (CCST) program


Certified Control System Technicians (CCSTs) calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables.

CCST question

Primary standard reference units and physical constants are maintained by ________.

B. testing labs
C. instrument techs
D. the plant instrument shop

CCST Answer

The correct answer is A, “NIST (National Institute of Standards and Technology).”All measurement units in the U.S. are based on the NIST standard measurements.

All other calibration measurements, such as those performed by testing labs and plant instrument shops, are considered to be done against secondary standards. By definition, these are “standards of unit measurement that are derived from a primary standard.”

NIST-certified instruments are calibrated at NIST, whereas NIST-traceable instruments are factory calibrated against NIST-certified standards. NIST-certified and NIST-traceable instruments are considered to be secondary standards.

Reference: Goettsche, L.D. (Editor), Maintenance of Instruments and Systems, Second Edition, ISA, 2005.