A10 Flashcards
What is the primary function of valves in a piping system?
a) To increase fluid velocity
b) To enhance temperature control
c) To allow, stop, regulate, and control fluid flow
d) To reduce fluid density
To allow, stop, regulate, and control fluid flow
Which of the following materials can be used to manufacture valves?
a) Only metals
b) Only nonmetals
c) Both metals and nonmetals
d) Only composite materials
Both metals and nonmetals
What happens when fluid pressure exceeds a valve’s set limit?
a) The valve allows excess fluid to bypass
b) The valve ceases functioning
c) The valve relieves overpressure
d) The valve increases its diameter
The valve relieves overpressure
What should be considered when selecting a suitable valve for an application?
a) Valve material cost only
b) Flow medium, design, piping criteria, and economics
c) Operator’s preference
d) None of these
Flow medium, design, piping criteria, and economics
What is the role of actuators in valve operation?
a) They monitor the fluid’s temperature
b) They control the valve using electrical, pneumatic, or hydraulic power
c) They measure the flow rate of fluids
d) They calculate the pressure drop across the valve
They control the valve using electrical, pneumatic, or hydraulic power
What does the term “ambient conditions” refer to in valve terminology?
a) The fluid’s temperature and pressure
b) The surrounding environment’s pressure and temperature
c) The valve’s internal pressure
d) The operating fluid’s velocity
The surrounding environment’s pressure and temperature
What is the purpose of a “block-and-bleed valve”?
a) To control flow rate
b) To block flow and allow trapped fluid to drain
c) To prevent backflow
d) To regulate temperature
To block flow and allow trapped fluid to drain
What does “bubble tight” mean in valve terminology?
a) A valve that prevents liquid leakage under high pressure
b) A valve that prevents air bubbles from forming
c) A valve that allows no air leakage in a closed position
d) A valve that operates at maximum efficiency
A valve that allows no air leakage in a closed position
What phenomenon occurs when fluid pressure falls below vapor pressure and bubbles collapse?
a) Choked flow
b) Cavitation
c) Backflow
d) Flashing
Cavitation
What is “cracking pressure”?
a) Pressure at which a valve starts to leak
b) Pressure at which a closed check valve begins to open
c) Maximum pressure a valve can withstand
d) Pressure at which a valve seat cracks
Pressure at which a closed check valve begins to open
What is the function of a “lantern ring” in a valve?
a) To allow lubrication of the packing
b) To support the valve disc
c) To prevent valve corrosion
d) To measure valve stroke
To support the valve disc
What type of valve is characterized by rapid opening or “pop” action?
a) Safety valve
b) Globe valve
c) Gate valve
d) Butterfly valve
Safety valve
What does “CWP” stand for in valve ratings?
a) Cold Water Pressure
b) Cold Working Pressure
c) Current Working Pressure
d) Critical Working Pressure
Cold Working Pressure
How are “small valves” generally classified by size?
a) NPS 1 and below
b) NPS 2 and smaller
c) NPS 3 and below
d) NPS 2½ and smaller
NPS 2 and smaller
What is a “fire-rated valve” designed for?
a) High-temperature water systems
b) Fire protection systems
c) Corrosive environments
d) High-pressure applications
Fire protection systems
What distinguishes “linear motion valves” from other types?
a) The valve closure member rotates in a circular path
b) The valve closure member moves in a straight line
c) The valve requires electrical power to operate
d) The valve is designed for high-pressure applications
The valve closure member moves in a straight line
What is a characteristic of “quarter-turn valves”?
a) They require multiple rotations to open
b) They open or close with a 90-degree turn
c) They are only used for gases
d) They cannot regulate flow
They open or close with a 90-degree turn
How the valve size is typically denoted in the metric system?
a) By nominal pipe size (NPS)
b) By nominal diameter (DN)
c) By flange size
d) By bore diameter
By nominal diameter (DN)
Which type of motion characterizes rotary motion valves?
a) Linear
b) Angular or circular
c) Oscillatory
d) Unidirectional
Angular or circular
How are valves classified based on mechanical motion?
a) By material
b) By flow characteristics
c) By the motion of the closure member
d) By pressure ratings
By the motion of the closure member
What is the typical angular movement for a quarter-turn valve?
a) 45 degrees
b) 90 degrees
c) 180 degrees
d) 360 degrees
90 degrees
How is valve size denoted in the imperial system?
a) Nominal diameter (DN)
b) Nominal pipe size (NPS)
c) Flow coefficient
d) Port diameter
Nominal pipe size (NPS)
What is the purpose of a “bypass” in a valve system?
a) To increase flow rate
b) To allow flow around a closed valve
c) To reduce system pressure
d) To prevent backflow
To allow flow around a closed valve
What determines a valve’s pressure-temperature rating?
a) Material composition and size
b) Operating environment conditions
c) Type of actuator
d) Flow medium viscosity
Material composition and size
What is the function of a “safety-relief valve”?
a) To block fluid backflow
b) To provide gradual pressure relief
c) To operate automatically during emergencies
d) To regulate fluid flow rates
To operate automatically during emergencies
How is “cold working pressure” (CWP) defined for valves?
a) Maximum allowable pressure at ambient temperature
b) Minimum operational temperature
c) Highest steam pressure rating
d) Flow rate in gallons per minute
Maximum allowable pressure at ambient temperature
What is a key advantage of “fire-rated valves”?
a) High durability in extreme conditions
b) Resistance to fire damage in emergencies
c) Cost-efficiency in all applications
d) Ability to handle toxic fluids safely
Resistance to fire damage in emergencies
What defines “large valves” in industry practice?
a) NPS 2 and smaller
b) NPS 3 and larger
c) NPS 2½ and larger
d) NPS 5 and above
NPS 2½ and larger
Which term describes the valve component designed to regulate or block fluid flow?
a) Actuator
b) Disc
c) Stem
d) Bonnet
Disc
What is the function of a “bonnet” in a valve?
a) To house the actuator
b) To seal the valve body
c) To measure flow rates
d) To increase pressure tolerance
To seal the valve body
What is a “quarter-turn valve” commonly used for?
a) Gradual flow regulation
b) Rapid opening and closing
c) Continuous flow measurement
d) High-pressure throttling
Rapid opening and closing
What is a key characteristic of “nonrising stem” valves?
a) The stem moves in a straight line
b) The stem does not rotate
c) The stem remains stationary while opening or closing
d) The stem is external to the valve body
The stem remains stationary while opening or closing
What is the function of a “check valve”?
a) To regulate fluid pressure
b) To prevent backflow
c) To maintain a constant flow rate
d) To isolate sections of a pipeline
To prevent backflow
What is a “relief valve” designed to do?
a) Measure fluid temperature
b) Open proportionally to excess pressure
c) Provide rapid emergency shutdown
d) Reduce flow turbulence
Open proportionally to excess pressure
What is the purpose of “hard facing” on valve components?
a) To prevent leakage
b) To increase resistance to wear and corrosion
c) To enhance flow rate
d) To enable higher temperature operation
To increase resistance to wear and corrosion
What is a “venturi port” designed for?
a) To throttle flow in high-pressure systems
b) To create a smaller flow passage
c) To facilitate backflow prevention
d) To enable full port flow characteristics
To create a smaller flow passage
What defines “linear flow characteristics”?
a) Flow rate changes proportionally with valve stroke
b) Flow velocity remains constant regardless of valve position
c) Flow increases exponentially with valve opening
d) Flow is independent of pressure changes
Flow rate changes proportionally with valve stroke
What is the role of a “yoke” in a valve?
a) To house the valve actuator
b) To position the stem nut or actuator
c) To control flow characteristics
d) To enhance pressure resistance
To position the stem nut or actuator
How does a “diaphragm valve” operate?
a) By rotating the disc
b) By using a flexible diaphragm to control flow
c) By regulating flow with a plug
d) By using a piston mechanism
By using a flexible diaphragm to control flow
What is the “stroke” of a valve?
a) The angle of rotation for rotary valves
b) The total travel distance of the closure member
c) The operating pressure range
d) The time required to open or close
The total travel distance of the closure member
What is a key feature of “knife gate valves”?
a) They are used in high-temperature applications
b) They can cut through solid particles in the flow
c) They are limited to gas applications
d) They operate at high velocities
They can cut through solid particles in the flow
Which of the following is a pressure-retaining part of a valve?
A. Valve stem
B. Valve actuator
C. Valve bonnet
D. Valve seat
Valve bonnet
What is the purpose of the bonnet in a valve?
A. To provide passage for fluid flow
B. To fasten the valve to the piping
C. To complete the pressure-retaining shell
D. To prevent galling of the valve seat
To complete the pressure-retaining shell
Which type of bonnet design is considered superior regarding leak tightness?
A. Bolted bonnet design
B. Threaded bonnet design
C. Pressure-seal bonnet design
D. Integral bonnet design
Pressure-seal bonnet design
What does the term “valve trim” refer to?
A. The pressure-retaining parts of a valve
B. The external parts used for operation
C. The removable and replaceable internal parts in contact with the flow medium
D. The bolting materials used for sealing
The removable and replaceable internal parts in contact with the flow medium
What is a common issue with non-rising stem valves?
A. The stem threads are exposed to the flow medium
B. They require more space for operation
C. They cannot be used for buried service
D. The stem cannot indicate if the valve is open or closed
The stem cannot indicate if the valve is open or closed
What is the primary function of stem packing in a valve?
A. To prevent leakage to the environment
B. To protect the valve from external pressure
C. To allow the flow medium to pass through smoothly
D. To adjust the flow rate of the fluid
To prevent leakage to the environment
Which type of valve is primarily used to stop or isolate flow in a piping system?
A. Check valve
B. Gate valve
C. Regulating valve
D. Pressure-relief valve
Gate valve
What is the main requirement of a regulating valve?
A. To ensure a tight shutoff when closed
B. To provide predictable flow control based on its position
C. To allow rapid closure during backflow
D. To resist pressure binding
To provide predictable flow control based on its position
Which of the following valves is used to prevent backflow?
A. Ball valve
B. Globe valve
C. Check valve
D. Butterfly valve
Check valve
How does a pressure relief valve operate under excess pressure conditions?
A. It opens by manual intervention
B. It uses a compressed spring to release excess pressure automatically
C. It rotates the valve disc to adjust the flow
D. It bursts open and cannot be reused
It uses a compressed spring to release excess pressure automatically
What is the primary function of a gate valve?
A. To regulate fluid flow
B. To prevent backflow
C. To serve as an isolation valve
D. To reduce pressure fluctuations
To serve as an isolation valve
Why are gate valves not recommended for throttling flow?
A. They cannot handle high-pressure
B. Erosion and vibration can damage the disc and seats
C. They are not bidirectional
D. They have a high-pressure loss
Erosion and vibration can damage the disc and seats
Which of the following is an advantage of gate valves?
A. Quick-opening mechanism
B. Minimal pressure loss when fully open
C. High resistance to thermal binding
D. Compact design
Minimal pressure loss when fully open
Which type of gate valve is preferred for buried service?
A. Rising stem gate valve
B. Non-rising stem gate valve
C. Double-disc gate valve
D. Conduit gate valve
Non-rising stem gate valve
In a rising stem gate valve, what indicates whether the valve is open or closed?
A. Position of the handwheel
B. Stem position
C. Pressure gauge reading
D. Flow rate measurement
Stem position
What type of stem motion is typically used in ball, plug, and butterfly valves?
A. Linear motion
B. Rotary motion
C. Sliding motion
D. Rising motion
Rotary motion
Why are trim materials often different from valve body materials?
A. To reduce production costs
B. To match the pressure rating of the valve
C. To provide properties that withstand specific forces and conditions
D. To simplify valve maintenance
To provide properties that withstand specific forces and conditions
What is the primary design requirement of a stop valve?
A. To maintain a constant pressure
B. To minimize resistance to flow in the fully open position
C. To allow flow in one direction only
D. To provide predictable flow control based on the valve’s position.
To minimize resistance to flow in the fully open position
What is a key advantage of forged steel valves compared to cast steel valves?
A. Better corrosion resistance
B. Higher pressure and temperature ratings
C. Lower manufacturing cost
D. Increased resistance to flow turbulence
Higher pressure and temperature ratings
Which type of valve is primarily used for throttling flow?
A. Gate valve
B. Globe valve
C. Check valve
D. Ball valve
Globe valve
What is the primary function of a check valve?
A. To regulate flow
B. To prevent backflow
C. To isolate portions of a system
D. To reduce pressure fluctuations
To prevent backflow
What feature distinguishes a lift check valve from a swing check valve?
A. It requires a higher flow velocity to open
B. It has a shorter service life
C. It operates only in horizontal pipelines
D. It uses a guided disc that moves vertically
It uses a guided disc that moves vertically
Which type of valve is best suited for high-frequency opening and closing operations?
A. Globe valve
B. Butterfly valve
C. Gate valve
D. Plug valve
Butterfly valve
Which part of a butterfly valve provides sealing against the flow medium?
A. The disc
B. The stem
C. The seat
D. The actuator
The seat
What type of actuator is commonly used for large butterfly valves?
A. Manual handwheel
B. Pneumatic actuator
C. Hydraulic actuator
D. Gear operator
Pneumatic actuator
What is the primary function of a ball valve?
A. To regulate flow with high precision
B. To provide a quick shutoff or opening
C. To handle throttling applications
D. To prevent backflow
To provide a quick shutoff or opening
Which material is commonly used for ball valve seats in high-temperature applications?
A. Rubber
B. Nylon
C. PTFE
D. Metal
Metal
What is a key advantage of plug valves?
A. Compact design and low cost
B. Tight shutoff and quick operation
C. Ability to handle high-temperature applications
D. Precise flow control in throttling
Tight shutoff and quick operation
In low-pressure and low-temperature systems, such as fire protection or water distribution pipelines, which type of gate valve is commonly used?
A. Threaded-end gate valves.
B. Socket-welding gate valves.
C. Flanged gate valves.
D. Butt-welding gate valves.
Flanged gate valves.
Which of the following is an advantage of a globe valve compared to a gate valve?
A. Lower pressure drop
B. Shorter stroke
C. Greater flow capacity
D. Longer service life
Shorter stroke
In which application is a globe valve particularly suitable?
A. Regulating flow in cooling water systems
B. High-pressure pipeline isolation
C. Abrasive slurry handling
D. Gas compression systems
Regulating flow in cooling water systems
Which of the following is NOT a typical application of globe valves?
A. Boiler vents and drains
B. Turbine seals and drains
C. Abrasive slurry pipelines
D. Feedwater and chemical feed systems
Abrasive slurry pipelines
Which of the following types of check valves consists of a disc in the form of a piston?
A. Swing check valve
B. Lift check valve
C. Ball check valve
D. Tilting-disc check valve
Lift check valve
What is a significant advantage of check valves?
A. They allow manual control of flow direction.
B. They are fast-acting and self-actuated.
C. They require minimal maintenance.
D. They allow internal parts to be inspected easily.
They are fast-acting and self-actuated.
Which of the following is a disadvantage of check valves?
A. They cannot handle high pressures.
B. The valve disc can stick in the open position.
C. They are not compatible with flanged ends.
D. They require external power to actuate.
The valve disc can stick in the open position.
What is a key feature of swing check valves?
A. The disc is fully guided during movement.
B. They are suitable for high-pressure, high-velocity applications.
C. The seating angle can range from 0° to 45°.
D. They require a spring-assist closure in all configurations.
The seating angle can range from 0° to 45°.
Which type of check valve is specifically adapted for high-pressure service with high flow velocity?
A. Swing check valve
B. Lift check valve
C. Tilting disc check valve
D. Folding disc check valve
Lift check valve
What is a significant advantage of ball valves over gate valves?
A. Bubble-tight service
B. Suitable for high-pressure applications
C. More durable construction
D. Easier to repair in-line
Bubble-tight service
What is the characteristic of a full-port ball valve?
A. The port is one pipe size smaller than the line size
B. The port is equal in size to the inside diameter of the pipe
C. The port is two sizes larger than the line size
D. The valve is designed only for low-pressure service
The port is equal in size to the inside diameter of the pipe
What is a significant disadvantage of ball valves?
A. They cannot handle high temperatures.
B. They are unsuitable for sustained throttling applications.
C. They are difficult to install in tight spaces.
D. They require frequent maintenance for bubble-tight service.
They are unsuitable for sustained throttling applications.
In which of the following applications are ball valves typically used?
A. Regulating gas flow
B. High-pressure steam throttling
C. Low-point drains and high-point vents
D. Filtering slurry in pipelines
Low-point drains and high-point vents
What is the primary use of plug valves?
A. For applications requiring bubble-tight service
B. For quick shutoff in steam, water, oil, and gas services
C. For sustained throttling in high-pressure systems
D. For chemical services with extremely high temperatures
For quick shutoff in steam, water, oil, and gas services
What is the most common shape of the port in the tapered plug of a plug valve?
A. Square
B. Triangular
C. Rectangular
D. Oval
Rectangular
Why are flanged joints commonly used in refineries and chemical plants?
A) They are less expensive than welded joints
B) They allow easier assembly and disassembly
C) They are compatible with all piping materials
D) They do not require maintenance
They allow easier assembly and disassembly
What is a common characteristic of piping joints in plumbing systems?
A) They use threaded, soldering, and brazing joints
B) They are always welded
C) They do not require regular inspections
D) They are flanged for high-pressure applications
They use threaded, soldering, and brazing joints
What is a fail-closed actuator mode?
A) The valve remains in its last position after power failure.
B) The valve is forced into the closed position after power failure.
C) The valve stays locked in an open position.
D) The valve automatically opens partially under pressure.
The valve is forced into the closed position after power failure.
Which actuator type utilizes compressed air for operation?
A) Electric motor actuator
B) Hydraulic actuator
C) Pneumatic actuator
D) Solenoid actuator
Pneumatic actuator
What type of actuator is best suited for quarter-turn valves?
A) Spur gear actuator
B) Worm gear actuator
C) Piston actuator
D) Linear actuator
Worm gear actuator
Which actuator type is commonly used with pilot-operated valves?
A) Hydraulic actuator
B) Solenoid actuator
C) Pneumatic actuator
D) Gear actuator
Solenoid actuator
What is a key consideration when selecting a valve for a specific application?
A) The valve material only
B) The valve size alone
C) The system’s design pressure and temperature
D) The actuator type
The system’s design pressure and temperature
What is the primary function of a stop valve?
A) To regulate fluid flow
B) To isolate a portion of the piping system
C) To prevent reverse flow
D) To relieve system pressure
To isolate a portion of the piping system
What is a common concern when using threaded joints in valves?
A) High cost of installation
B) Restrictions on joint size
C) Potential for leakage
D) Complex maintenance procedures
Potential for leakage
What type of actuator is typically used with a large gate valve?
A. Solenoid actuator
B. Pneumatic actuator
C. Bevel-gear actuator
D. Hydraulic actuator
Bevel-gear actuator
What is the primary function of a check valve?
A. To regulate flow rate
B. To prevent reverse flow
C. To reduce pressure drops
D. To isolate piping sections
To prevent reverse flow
What material is commonly used for the diaphragms of diaphragm valves in corrosive applications?
A. Teflon
B. PVC
C. Neoprene
D. Hypalon
Teflon
What is the primary reason for using actuator-driven valves?
A. Cost-effectiveness
B. Compatibility with all systems
C. Ease of operation in large or remote systems
D. Resistance to corrosion
Ease of operation in large or remote systems
Which of the following is a disadvantage of diaphragm valves?
A. High cost
B. Difficult maintenance
C. Limited pressure and temperature capabilities
D. Complex construction
Limited pressure and temperature capabilities
What is the primary application of a safety-relief valve?
A. Controlling fluid direction
B. Relieving overpressure in both liquid and gas systems
C. Isolating piping sections
D. Preventing leakage
Relieving overpressure in both liquid and gas systems
Which type of valve is most suitable for throttling applications?
A. Check valve
B. Gate valve
C. Globe valve
D. Diaphragm valve
Globe valve
Which actuator type utilizes compressed air to operate a valve?
A. Hydraulic actuator
B. Solenoid actuator
C. Pneumatic actuator
D. Electric motor actuator
Pneumatic actuator
What is a common advantage of butterfly valves?
A. Suitable for high-pressure applications only
B. Compact and lightweight design
C. Requires minimal torque to operate
D. Provides unrestricted flow
Compact and lightweight design
Why are fail-open actuators used in certain valve systems?
A. To ensure the valve opens during power failure
B. To prevent fluid contamination
C. To reduce pressure drops
D. To isolate piping sections
To ensure the valve opens during power failure
What type of valve is typically used for slurry applications?
A. Gate valve
B. Plug valve
C. Butterfly valve
D. Ball valve
Plug valve
What type of actuator is suitable for small stroke and low thrust applications?
A. Pneumatic actuator
B. Hydraulic actuator
C. Electric motor actuator
D. Solenoid actuator
Solenoid actuator
Which of the following valves is primarily used for precise flow control?
A. Ball valve
B. Check valve
C. Globe valve
D. Plug valve
Globe valve
What type of valve is typically used in vacuum service applications?
A. Diaphragm valve
B. Gate valve
C. Plug valve
D. Butterfly valve
Diaphragm valve
Which material is commonly used for high-temperature valve seats?
A. Neoprene
B. PVC
C. Graphite
D. Teflon
Graphite
Which valve type is ideal for applications requiring frequent directional changes of flow?
A. Globe valve
B. Multiport plug valve
C. Gate valve
D. Diaphragm valve
Multiport plug valve
Which actuator type is best suited for applications requiring high torque?
A. Solenoid actuator
B. Pneumatic actuator
C. Hydraulic actuator
D. Gear actuator
Hydraulic actuator
What is a major limitation of gate valves?
A. Limited size availability
B. Not suitable for throttling applications
C. Requires frequent maintenance
D. Low pressure rating
Not suitable for throttling applications
Why are soft seats used in valves?
A. To ensure bubble-tight sealing
B. To handle high temperatures
C. To reduce weight
D. To simplify construction
To ensure bubble-tight sealing
What is the main advantage of electric motor actuators?
A. Minimal cost
B. Precise control over valve position
C. High speed operation
D. Compatibility with all valve types
Precise control over valve position
In a diaphragm valve, what does the diaphragm primarily act as?
A. A sealing element only
B. A flexible pressure boundary
C. A flow regulation device
D. A rigid barrier
A flexible pressure boundary
What is a typical disadvantage of ball valves?
A. High cost
B. Complex design
C. Limited suitability for throttling
D. High pressure drop
Limited suitability for throttling
Which valve type is known for quick operation and low pressure drop?
A. Gate valve
B. Butterfly valve
C. Globe valve
D. Plug valve
Butterfly valve
What material is typically used for valve seats in cryogenic applications?
A. Teflon
B. Graphite
C. Neoprene
D. PVC
Teflon
Which valve type is most commonly used in fire protection systems?
A. Butterfly valve
B. Ball valve
C. Plug valve
D. Gate valve
Butterfly valve
