Instrumentation and Process Control

Question 1

________ refers to the use of instruments to monitor and regulate process
conditions.

Answer 1

Instrumentation

Question 2

The process variables that are commonly monitored in a refinery are:
.

Answer 2

Pressure
.
Temperature
.
Level
.
Flow

Question 3

List various components of a control loop and their functions

Answer 3

Controllers:
-Compare measured process variable values with the
corresponding set points to identify process deviations

Sensing Devices:

-Measure process variables
-Are of various types because these devices are used to
measure variables having different characteristics

Transmitters:

-Transfer signals or measurements from sensing devices to
controllers
-Can be an inherent part of sensing devices that provide
the measurement and output signals

Indicators or
Recorders:
-Receive measured signals from transmitters
-Facilitate observation and recording of process variable
values

End Devices:
-Final elements of the process control loop that directly
affect the process
-For example, control valve, the common type of end
device found in process units

Question 4

List various components of a control loop and their functions

Answer 4

Controllers:
-Compare measured process variable values with the
corresponding set points to identify process deviations

Sensing Devices:

-Measure process variables
-Are of various types because these devices are used to
measure variables having different characteristics

Transmitters:

-Transfer signals or measurements from sensing devices to
controllers
-Can be an inherent part of sensing devices that provide
the measurement and output signals

Indicators or
Recorders:
-Receive measured signals from transmitters
-Facilitate observation and recording of process variable
values

End Devices:
-Final elements of the process control loop that directly
affect the process
-For example, control valve, the common type of end
device found in process units

Question 5

1) ______ pressure scales are used to measure absolute pressure.

2) ______ zero is a condition where air and pressure are not available.

a. vacuum
b. gauge
c. theoretical
d. absolute

Answer 5

1) d. absolute
2) c. theoretical

Question 6

______is any pressure below atmospheric pressure. Using 14.7 psia as a starting point

a. gauge
b. vacuum
c. theoretical
d. absolute

Answer 6

b. vacuum

Question 7

pressure is used to measure the pressure difference between a system and the
atmosphere.

a. gauge
b. vacuum
c. theoretical
d. absolute

Answer 7

Gauge

Question 8

What elastic device is most often used in pressure gauges?

a. bourdon springs
b. bellows elements
c. diaphragms

Answer 8

a. bourdon springs

Question 9

What are 4 indirect level measurement devices?

Answer 9

.
Pressure-sensitive level gauge
.
Bubbler system
.
Nuclear system
.
Radar system

Question 10

A _______ level measurement system operates by directing radiation from a high-energy
radiation source through the contents of the vessel to a detector.
The ______ system consists of a high-energy radiation source and

a. bubbler
b. radar
c. nuclear
d. absolute

Answer 10

c. nuclear

Question 11

What level measurement system uses electromagnetic waves to measure level?

a. bubbler
b. radar
c. nuclear
d. absolute

Answer 11

b. radar

Question 12

A _______ cell measures the difference between two related pressures, such
as atmospheric pressure and hydrostatic pressure.
These cells can be used
to measure liquid level in both pressurized and nonpressurized tanks.

a. atmospheric pressure
b. differential pressure
c.

Answer 12

differential pressure

Question 13

An _______ _______ is a simple type of restriction used to measure the flow rate of fluid through
a pipe. An_______ _____ is a thin plate with a hole in the center.

a. dampener
b. orifice plate

Answer 13

orifice plate

Question 14

2. The differential pressure across the ______ ______ is measured using a differential
   pressure cell.

The differential pressure cell is connected to a local flow rate indication device to
obtain the flow rate through the pipe.
Alternatively, the differential pressure cell can be connected to a transmitter that
sends a signal to a remote device. The remote device, located in a control room,
records the flow rate data.

Answer 14

orifice plate

Question 15

______ flow meters use electrical conductivity of the fluid to measure the flow.

a. transducer
b. electrode
c. magnetic
d. conductivity

Answer 15

magnetic

Question 16

A ___ ____ _____ measures the mass per unit time, such as kilograms per second or
pounds per second, of the fluid flowing through the device.

a. mass flow meter
b. turbine flow meter
c. flume flow meter

Answer 16

mass flow meter

Question 17

____ ____ are the most common type of liquid concentration analyzers. ___ is a
measure of the hydrogen ion concentration of a solution and represents the acidity or
alkalinity of a solution.

Answer 17

pH analyzers

Question 18

_______ are devices that change or convert one type of signal to another type of
signal.

Answer 18

Transducers

Question 19

For pneumatic transmitters and transducers, you need to ensure that the required air
pressure is supplied to the instrument. This air is called _____ _____ and is produced by
a separate system to ensure clean dry air is supplied to instruments.

Answer 19

instrument air

Question 20

A ______ indicator is located at a distance from the equipment or system where the
process takes place. An instrument located in a control room is an example of this.

a. console
b. remote
c. local

Answer 20

remote

Question 21

____ are used to alert personnel when the values of process variables are outside the
normal operating range.

Answer 21

Alarms

Question 22

What is the 4 step procedure for high level alarm testing?

Answer 22

To test the high level alarm:
1. Close the bottom and top root valves of the separator.
2. Open the vent valve to the relief system.
3. Fill the level glass with water or test fluid until the level switch trips the alarm.
4. Note the actual level at which the alarm trips.

Question 23

Controllers can also be identified by their _____ ______ .
For example, a recording and indicating controller controls the process variable, provides
a visual indication of the process variable, and records the values of the process variable.

a. additional functions
b. federal id
c. chevrons id system

Answer 23

additional functions

Question 24

The _____ of an instrument is the degree of conformity of a measurement to a standard
or true value.

a. accuracy
b. sensitivity
c. speed of response
d. reproducibility

Answer 24

a. accuracy

Question 25

_______ in instrumentation is the ability to provide accurate readings constantly.

a. accuracy
b. sensitivity
c. speed of response
d. reproducibility

Answer 25

d. reproducibility