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

Faster signal transmission

Answer

Higher accuracy at full scale only

Answer

Use of smaller diameter wire

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

Too little proportional gain

Answer

A failed power supply

Answer

The setpoint being at zero

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 check valve

Answer

A relief valve

Answer

A control valve

Question 4

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

Accepted Answer

Electrical resistance of a metal element

Answer

Voltage between two metals

Answer

Gas pressure in a bulb

Answer

Light wavelength

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

Out of service

Answer

Located outdoors

Answer

Spare instruments

Question 6

A check valve is installed in a pump discharge line primarily to:

Accepted Answer

Prevent reverse flow (backflow) when the pump stops

Answer

Regulate the flow rate

Answer

Reduce pipe pressure

Answer

Measure flow

Question 7

The term 'span' of a transmitter refers to:

Accepted Answer

The difference between the upper and lower range values

Answer

The lowest value it can read

Answer

The physical length of the device

Answer

The signal output type