July 2008

Documenting skills is value-add

ISA certification provides an objective, third-party assessment, and confirmation of a person's skills. It gives manufacturing and factory staff the opportunity to differentiate themselves from their peers and gain recognition. InTech covers two certification areas in this monthly Certification department.

ISA Certified Automation Professional (CAP) program

Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.

The following question comes from the CAP study guide, Performance Domain I, Feasibility Study, Identify scope and justify the automation project

CAP question

MOST initial project budgetary cost estimates have an acceptable margin of error of plus or minus:

A. 10%
B. 30%
C. 50%
D. 70%

CAP answer

The best answer is B, 30%.

It is common practice to have a preliminary estimate with a margin of error of plus or minus 30%.

A more detailed estimate takes place before presenting the bid to reduce the margin of error to 10%.

Reference: Michael D. Whitt, Successful Instrument and Control System Design, ISA Press, 2004

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.

This question comes from the Level I study guide, Domain 3, Troubleshooting. Level I represents a professional who has a five-year total of education, training, and/or experience.

CCST question

A piston actuator:

A. Seldom has both a pneumatic positioner and helper spring
B. Can only be actuated by hydraulic pressure above 100 psig
C. Cannot be made fail safe with out electric limit switches
D. Can be used if a long stroke or high actuator pressure is required

CCST answer

An actuator is a device that applies the force necessary to cause a valve's closure member to move. They often provide a failsafe function. If there is some crisis as to process or power, the actuator will place the valve in a predetermined safe position usually either full open or full closed.

The pneumatic actuator is the most popular, whether diaphragm or piston variety. The piston actuator can operate at higher pressures and longer strokes are possible than those actuators that leverage the diaphragm.

Piston actuators can be spring-opposed, but many times are in dual-acting configuration whereby compressed air applies to both sides of the piston with the net force being the pressure difference. 

The correct answer is D.


Nicholas Sheble (nsheble@isa.org) writes and edits Certification Review.