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Today's automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for information about the CCST program. This question is from the Level III study guide, Domain 2, Loop checking. (Level III represents a professional who has a 13-year total of education, training, and/or experience.)
Using ISA symbols on a P&ID (piping and instrument diagram), a solid line with three marks crossed by another hash mark represents:
a) electric binary signal
b) pneumatic binary signal
c) undefined signal
d) capillary tubing
e) none of the above
ISA-5.1-1984 - (Revised 2009) Instrumentation Symbols and Identification provides sufficient information to enable anyone reviewing any document depicting process measurement and control (who has a reasonable amount of process knowledge) to understand the means of measurement and control of the process.
The symbolism and identification methods provided in this standard are applicable to all classes of process measurement and control instrumentation. They can describe discrete instruments and their functions. They can also describe the analogous functions of systems that are variously termed shared display, shared control, distributed control, and computer control.
The best answer is A.