Ramsay Test Process Flow and Instrumentation 4

Question 1

The main reason to install instruments with a 4-20 mA signal rather than 0-20 mA is that 4-20 mA allows:

Accepted Answer

Detection of a broken wire or dead instrument (live zero)

Answer

The 4 mA 'live zero' means a reading of 0 mA indicates a fault such as a broken wire, not a valid zero value.

Question 2

A control loop is 'hunting' or oscillating continuously around setpoint. This is most often caused by:

Accepted Answer

Too much gain or too little damping in the tuning

Answer

Excessive gain or insufficient damping causes the loop to overshoot repeatedly and oscillate.

Question 3

Which device is used to physically isolate a section of pipe for maintenance while providing positive visual confirmation it is blocked?

Accepted Answer

A blind flange or spectacle blind

Answer

A blind flange or spectacle blind provides a positive, visible mechanical block for isolation during maintenance.

Question 4

An RTD (resistance temperature detector) measures temperature by sensing the change in:

Accepted Answer

Electrical resistance of a metal element

Answer

An RTD relies on the predictable increase in electrical resistance of a metal (often platinum) as temperature rises.

Question 5

On a P&ID, a dashed line forming a circle around a group of instruments usually indicates they are:

Accepted Answer

Part of a shared display or distributed control system function

Answer

A bubble with an enclosing form or shared symbol denotes shared display/control such as a DCS function.

Ramsay Test Practice Test