CHAPTER 10 - RELIEF SIZING

Question 1

What is the primary purpose of a relief sizing in a pressurized system?

Answer 1

b) To relieve excess pressure and prevent system failure

Question 2

Which of the following is the most important factor in relief sizing?

Answer 2

c) Maximum flow rate of the system

Question 3

When a relief sizing, which of the following parameters is critical to avoid sizing chatter or instability?

Answer 3

d) Backpressure

Question 4

The orifice size of a relief sizing is determined primarily by:

Answer 4

b) The required flow capacity

Question 5

A pressure relief sizing set to open at 100 psi would be considered which of the following?

Answer 5

b) The size’s set pressure

Question 6

For liquid service, what is the most commonly used method to size a relief sizing?

Answer 6

a) Flow coefficient method

Question 7

Which of the following factors affects the required size of a relief sizing for gas service?

Answer 7

d) All of the above

Question 8

How is the required relief sizing capacity affected by the fluid’s temperature?

Answer 8

a) Higher temperatures typically increase the flow rate requirement.

Question 9

What is the role of the “set pressure” in sizing a relief sizing?

Answer 9

a) It determines when the sizing will open.

Question 10

In relief sizing, what is the impact of “backpressure” on the size?

Answer 10

c) It can reduce the size’s capacity, requiring a larger size.

Question 11

Which of the following best describes the goal of loss prevention?

Answer 11

c) To prevent the existence of hazards, though some may be unavoidable

Question 12

What is the primary hazard during the milling process to make flour from wheat?

Answer 12

b) The production of substantial quantities of flammable dust

Question 13

What is the main function of deflagration venting in explosion control?

Answer 13

b) To reduce the impact of explosions by directing energy away from people and equipment

Question 14

Why are blowout panels designed to be weaker than the structure’s walls?

Answer 14

d) To ensure panels detach and vent explosive energy safely

Question 15

In buildings with highly explosive dusts or vapors, which additional safety measure may be used?

Answer 15

a) The structure’s entire walls and roof may be constructed with blowout panels

Question 16

For low-pressure structures designed to withstand pressures of up to 1.5 psi (0.1 bar gauge), which design technique is traditionally used?

Answer 16

b) Runes design technique

Question 17

For high-pressure structures that can withstand pressures above 1.5 psig (0.1 bar gauge), the vent design is primarily based on which of the following?

Answer 17

c) The deflagration index for gases or dusts

Question 18

Why is venting required for process vessels exposed to external fires?

Answer 18

b) To avoid the explosion of vessels due to heating and boiling of liquids

Question 19

In the event of an external fire, why is two-phase flow unlikely during venting for process vessels?

Answer 19

b) Because boiling only occurs next to the vessel wall, creating a thin two-phase froth

Question 20

What can happen if process fluids in vessels or pipes are fully contained and undergo thermal expansion?

Answer 20

c) The expansion can damage pipes and vessels due to increased pressure

Question 21

What is a primary reason for using pilot-operated reliefs over other types of reliefs?

Answer 21

b) They have greater accuracy and control for varying pressures

Question 22

How do the calculation methods for sizing pilot-operated reliefs compare to those for spring-operated reliefs?

Answer 22

b) They are similar and follow comparable calculation procedures

Question 23

Where can engineers find detailed methods for calculating the sizing of buckling-pin reliefs?

Answer 23

c) In the vendor manuals or by consulting specialized relief sizing companies

Question 24

Why might buckling-pin reliefs require specialized consultation for sizing?

Answer 24

a) Their sizing methods are
proprietary and not widely
Published

Question 25

In the context of industrial safety, which type of relief device would an engineer likely need to consult a vendor for assistance with?

Answer 25

c) buckling-pin relief device

Question 26

What type of flow is generally expected during the relief process when a runaway reaction occurs within a reactor vessel?

Answer 26

c) two-phase flow

Question 27

What essential data does the vent sizing package (VSP) laboratory apparatus provide for relief area sizing?

Answer 27

b) temperature and pressure rise data

Question 28

Why is the most common reactor system referred to as a “tempered” reactor?

Answer 28

c) it contains a volatile liquid that
vaporizes during relieving,

Question 29

How does the vaporization of a volatile liquid in a tempered reactor aid in controlling a runaway reaction?

Answer 29

c) it removes energy through the heat of vaporization, slowing the
temperature rise

Question 30

What is the primary purpose of the heat of vaporization in a tempered reactor system during a runaway reaction?

Answer 30

b) to cool the system by removing excess energy

Question 31

Which of the following factors can most directly affect the likelihood of “chattering” in a spring-operated relief sizing?

Answer 31

a) The size’s set pressure relative
to operating pressure

Question 32

In a reactor system with a runaway reaction, what is one of the primary reasons for expecting two-phase flow in the relief process?

Answer 32

c) The exothermic reaction causes liquid to vaporize rapidly

Question 33

What is a primary design consideration when selecting a rupture disc for a reactor experiencing two-phase flow?

Answer 33

c) The disc’s ability to handle
transient flow rates and mixed-phase discharge

Question 34

In the event of an external fire, which design feature of a relief device is crucial for ensuring safety in pressurized vessels?

Answer 34

c) A pressure-relief sizing set to
respond to increased vapor pressure from heated contents

Question 35

Why might a tempered reactor, as opposed to a non-tempered one, be less susceptible to rapid pressure spikes during a runaway reaction?

Answer 35

c) The vaporization of a volatile liquid absorbs energy, slowing temperature rise

Question 36

Why is it important to have a retention mechanism for blowout panels during a deflagration?

Answer 36

b) To prevent the panel from moving at high velocity and causing damage

Question 37

Which of the following is a necessary feature for blowout panels in deflagration protection?

Answer 37

c) Thermal insulation of panels

Question 38

What factors are considered when designing the relief area of blowout panels?

Answer 38

c) Explosive behavior of the dust or vapor, allowable overpressure, and structure volume

Question 39

How are low-pressure structures defined in deflagration design?

Answer 39

a) Structures made of low-strength materials like sheet metal, withstanding up to 1.5 psig

Question 40

High-pressure structures in deflagration design typically include which types of buildings?

Answer 40

b) Steel process vessels and concrete buildings that withstand more than 1.5 psig