CHAPTER 10 - RELIEF SIZING Flashcards
What is the primary purpose of a relief sizing in a pressurized system?
b) To relieve excess pressure and prevent system failure
Which of the following is the most important factor in relief sizing?
c) Maximum flow rate of the system
When a relief sizing, which of the following parameters is critical to avoid sizing chatter or instability?
d) Backpressure
The orifice size of a relief sizing is determined primarily by:
b) The required flow capacity
A pressure relief sizing set to open at 100 psi would be considered which of the following?
b) The size’s set pressure
For liquid service, what is the most commonly used method to size a relief sizing?
a) Flow coefficient method
Which of the following factors affects the required size of a relief sizing for gas service?
d) All of the above
How is the required relief sizing capacity affected by the fluid’s temperature?
a) Higher temperatures typically increase the flow rate requirement.
What is the role of the “set pressure” in sizing a relief sizing?
a) It determines when the sizing will open.
In relief sizing, what is the impact of “backpressure” on the size?
c) It can reduce the size’s capacity, requiring a larger size.
Which of the following best describes the goal of loss prevention?
c) To prevent the existence of hazards, though some may be unavoidable
What is the primary hazard during the milling process to make flour from wheat?
b) The production of substantial quantities of flammable dust
What is the main function of deflagration venting in explosion control?
b) To reduce the impact of explosions by directing energy away from people and equipment
Why are blowout panels designed to be weaker than the structure’s walls?
d) To ensure panels detach and vent explosive energy safely
In buildings with highly explosive dusts or vapors, which additional safety measure may be used?
a) The structure’s entire walls and roof may be constructed with blowout panels
For low-pressure structures designed to withstand pressures of up to 1.5 psi (0.1 bar gauge), which design technique is traditionally used?
b) Runes design technique
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?
c) The deflagration index for gases or dusts
Why is venting required for process vessels exposed to external fires?
b) To avoid the explosion of vessels due to heating and boiling of liquids
In the event of an external fire, why is two-phase flow unlikely during venting for process vessels?
b) Because boiling only occurs next to the vessel wall, creating a thin two-phase froth
What can happen if process fluids in vessels or pipes are fully contained and undergo thermal expansion?
c) The expansion can damage pipes and vessels due to increased pressure
What is a primary reason for using pilot-operated reliefs over other types of reliefs?
b) They have greater accuracy and control for varying pressures
How do the calculation methods for sizing pilot-operated reliefs compare to those for spring-operated reliefs?
b) They are similar and follow comparable calculation procedures
Where can engineers find detailed methods for calculating the sizing of buckling-pin reliefs?
c) In the vendor manuals or by consulting specialized relief sizing companies
Why might buckling-pin reliefs require specialized consultation for sizing?
a) Their sizing methods are
proprietary and not widely
Published
In the context of industrial safety, which type of relief device would an engineer likely need to consult a vendor for assistance with?
c) buckling-pin relief device
What type of flow is generally expected during the relief process when a runaway reaction occurs within a reactor vessel?
c) two-phase flow
What essential data does the vent sizing package (VSP) laboratory apparatus provide for relief area sizing?
b) temperature and pressure rise data
Why is the most common reactor system referred to as a “tempered” reactor?
c) it contains a volatile liquid that
vaporizes during relieving,
How does the vaporization of a volatile liquid in a tempered reactor aid in controlling a runaway reaction?
c) it removes energy through the heat of vaporization, slowing the
temperature rise
What is the primary purpose of the heat of vaporization in a tempered reactor system during a runaway reaction?
b) to cool the system by removing excess energy
Which of the following factors can most directly affect the likelihood of “chattering” in a spring-operated relief sizing?
a) The size’s set pressure relative
to operating pressure
In a reactor system with a runaway reaction, what is one of the primary reasons for expecting two-phase flow in the relief process?
c) The exothermic reaction causes liquid to vaporize rapidly
What is a primary design consideration when selecting a rupture disc for a reactor experiencing two-phase flow?
c) The disc’s ability to handle
transient flow rates and mixed-phase discharge
In the event of an external fire, which design feature of a relief device is crucial for ensuring safety in pressurized vessels?
c) A pressure-relief sizing set to
respond to increased vapor pressure from heated contents
Why might a tempered reactor, as opposed to a non-tempered one, be less susceptible to rapid pressure spikes during a runaway reaction?
c) The vaporization of a volatile liquid absorbs energy, slowing temperature rise
Why is it important to have a retention mechanism for blowout panels during a deflagration?
b) To prevent the panel from moving at high velocity and causing damage
Which of the following is a necessary feature for blowout panels in deflagration protection?
c) Thermal insulation of panels
What factors are considered when designing the relief area of blowout panels?
c) Explosive behavior of the dust or vapor, allowable overpressure, and structure volume
How are low-pressure structures defined in deflagration design?
a) Structures made of low-strength materials like sheet metal, withstanding up to 1.5 psig
High-pressure structures in deflagration design typically include which types of buildings?
b) Steel process vessels and concrete buildings that withstand more than 1.5 psig
