Valves Flashcards
Which one of the following describes the function of a safety valve?
A. Provide overpressure protection to limit the internal pressure in vessels.
B. Control pressure in a system to maintain optimum operational conditions.
C. Sound a warning by lifting at a predetermined value slightly higher than operating pressure.
D. Modulate open as necessary to maintain system pressure and/or temperature within normal limits.
Provide overpressure protection to limit the internal pressure in vessels.
A vertical safety valve has a compressed spring assembly that is applying 1,200 lbf to the top of the
valve disk in opposition to system pressure. System pressure is being exerted on the underside of the
valve disk that is 3 inches in diameter.
Which one of the following is the approximate system pressure at which the safety valve will open?
A. 44 psig
B. 64 psig
C. 128 psig
D. 170 psig
170 psig
A vertical safety valve with a 3-inch diameter disk has a spring applying 1,000 lbf to the top of the
valve disk in opposition to system pressure. Which one of the following is the approximate system
pressure at which the safety valve will begin to open?
A. 35 psig
B. 111 psig
C. 141 psig
D. 444 psig
141 psig
Refer to the drawing of a typical safety valve (see figure below).
The component indicated by the solid arrow is used when necessary to manually…
A. ratchet open the safety valve.
B. pop open the safety valve.
C. gag shut the safety valve.
D. determine the position of the safety valve.
pop open the safety valve.
A vertical safety valve has a compressed spring assembly that is applying 2,500 lbf to the top of the
valve disk in opposition to system pressure. System pressure is being exerted on the underside of the
valve disk that is 5 inches in diameter.
Which one of the following is the approximate system pressure at which the safety valve will open?
A. 32 psig
B. 127 psig
C. 159 psig
D. 500 psig
127 psig
A vertical safety valve with a 2-inch diameter disk has a compressed spring applying 2,400 lbf to the
top of the valve disk in opposition to system pressure. Which one of the following is the approximate
system pressure at which the safety valve will open?
A. 95 psig
B. 191 psig
C. 382 psig
D. 764 psig
764 psig
Given the following specifications for a main steam safety valve (MSSV):
Setpoint pressure (MSSV starts to open) = 1,200 psia
Maximum pressure (MSSV will be fully open) = 1,230 psia
Reseat pressure (MSSV will be fully closed) = 1,140 psia
Which one of the following is the percent blowdown for the MSSV?
A. 2.5 percent
B. 5.0 percent
C. 7.5 percent
D. 33.3 percent
5.0 percent
A completely full water storage tank is being hydrostatically tested to 100 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 10 gpm. The tank is
protected by a safety valve and a relief valve; both valves discharge to the atmosphere. Each valve
has an opening setpoint of 105 psig and a maximum rated discharge flow rate of 6 gpm. The PDP is
inadvertently left running when tank pressure reaches 100 psig.
With the PDP still running, tank pressure will stabilize __________ 105 psig; and the greater mass
flow rate will be coming from the __________ valve.
A. at; safety
B. above; safety
C. at; relief
D. above; relief
above; safety
Given the following pressure specifications for a safety relief valve (SRV):
Setpoint pressure (SRV will start to open) = 1,200 psia
Maximum pressure (SRV will be fully open) = 1,242 psia
Reseat pressure (SRV will be fully closed) = 1,152 psia
Which one of the following is the percent accumulation for the SRV?
A. 2.5 percent
B. 3.0 percent
C. 3.5 percent
D. 4.0 percent
3.5 percent
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 8 gpm. The tank is
protected by a relief valve and a safety valve; both valves discharge to the atmosphere. Each valve
has an opening setpoint of 205 psig and a maximum rated discharge flow rate of 6 gpm. The PDP is
inadvertently left running when tank pressure reaches 200 psig.
When conditions stabilize with the PDP still running, the relief valve will be __________ open; and
the safety valve will be discharging a flow rate of approximately __________ to the atmosphere.
A. partially; 6 gpm
B. partially; 2 gpm
C. fully; 6 gpm
D. fully; 2 gpm
partially; 6 gpm
Refer to the drawing of two identical water storage tanks (see figure below). Tank A is protected by a
relief valve and Tank B is protected by a safety valve. Each valve has an opening setpoint of 205 psig
and a maximum rated discharge flow rate of 8 gpm.
The tanks are being hydrostatically tested to 200 psig. Each tank is being supplied with a smooth and
constant flow rate of 2 gpm from separate positive displacement pumps (PDPs). Both PDPs are
inadvertently left running when tank pressures reach 200 psig.
With the PDPs running continuously, what will be the resulting status of the relief and safety valves?
Relief Valve Status
Safety Valve Status
A. Partially open Partially open
B. Partially open Cycling between fully
open and fully closed
C. Cycling between fully
open and fully closed Partially open
D. Cycling between fully
open and fully closed
Cycling between fully
open and fully closed
Partially open Cycling between fully
open and fully closed
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 8 gpm. The tank is
protected by a relief valve and a safety valve that both discharge to the atmosphere. The valves have
the following characteristics:
* The relief valve opening setpoint is 200 psig with an accumulation of 5 percent.
* The safety valve opening setpoint is 240 psig with a blowdown of 5 percent.
* Both valves have a maximum discharge flow rate of 6 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
When conditions stabilize with the PDP still running, the relief valve will be __________ open; and
the safety valve will be discharging a flow rate of approximately __________ to the atmosphere.
A. partially; 6 gpm
B. partially; 2 gpm
C. fully; 6 gpm
D. fully; 2 gpm
fully; 2 gpm
A main steam system uses a combination of safety valves and relief valves for overpressure protection.
Which one of the following describes a major design consideration for installing both types of valves
in the same system?
A. The safety valves are installed to prevent chattering of the relief valves during normal power
operation.
B. The safety valves are installed to prevent unnecessary opening of the relief valves during a steam
pressure transient.
C. The relief valves are installed to prevent chattering of the safety valves during normal power
operation.
D. The relief valves are installed to prevent unnecessary opening of the safety valves during a steam
pressure transient.
The relief valves are installed to prevent unnecessary opening of the safety valves during a steam
pressure transient.
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 8 gpm. The tank is
protected by a relief valve and a safety valve that both discharge to the atmosphere. The valves have
the following characteristics:
* The relief valve opening setpoint is 220 psig with an accumulation of 5 percent.
* The safety valve opening setpoint is 260 psig with a blowdown of 5 percent.
* Both valves have a maximum discharge flow rate of 6 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
After a few minutes with the PDP still running, the relief valve will be discharging a flow rate of
approximately __________; and the safety valve will be __________.
A. 2 gpm; partially open
B. 6 gpm; partially open
C. 2 gpm; cycling between fully open and fully closed
D. 6 gpm; cycling between fully open and fully closed
6 gpm; cycling between fully open and fully closed
The primary purpose of a pressure relief valve is to…
A. reduce system energy.
B. reduce system pressure.
C. maintain system integrity.
D. maintain system mass.
maintain system integrity.
The difference between the setpoint pressure at which a safety valve opens and the pressure at which it
closes is called…
A. blowdown.
B. accumulation.
C. setpoint tolerance.
D. setpoint deviation.
blowdown
The difference between the setpoint pressure at which a relief valve begins to open and the pressure at
which it is fully open is called…
A. setpoint deviation.
B. setpoint tolerance.
C. accumulation.
D. blowdown.
accumulation
Which one of the following is a difference between a typical relief valve and a typical safety valve?
A. The actuator closing spring on a relief valve is in a compressed state whereas the actuator closing
spring on a safety valve acts in tension.
B. A relief valve gradually opens as pressure increases above the setpoint pressure whereas a safety
valve pops open at the setpoint pressure.
C. Relief valves are capable of being gagged whereas safety valves are not.
D. The blowdown of a relief valve is greater than the blowdown of a safety valve.
A relief valve gradually opens as pressure increases above the setpoint pressure whereas a safety
valve pops open at the setpoint pressure.
Refer to the drawing of two identical pressure vessels with identical relief valve protection (see figure
below).
Both vessels have been pressurized to 50 psig and then isolated. Vessel A is completely filled with
water at 150°F. Vessel B is in a saturated condition with one-half steam (100 percent quality) and
one-half water (0 percent quality) by volume.
If both relief valves fully open simultaneously, the faster pressure reduction will occur in vessel
__________; and if both relief valves close at 40 psig, the greater mass loss will have occurred in
vessel __________.
A. A; A
B. A; B
C. B; A
D. B; B
A; B
Water storage tanks A and B are identical except that tank A receives overpressure protection from a
relief valve, whereas tank B uses a safety valve. The relief valve and safety valve have the same
pressure setpoints and design flow rates.
Water is continuously added to each tank at the same rate (50 percent of the design flow rate of the
relief and safety valves). After the tanks are completely full, tank A pressure will __________; and
tank B pressure will __________.
A. fluctuate within a few percent of the pressure setpoint; stabilize slightly above the pressure
setpoint
B. fluctuate within a few percent of the pressure setpoint; fluctuate within a few percent of the
pressure setpoint
C. stabilize slightly above the pressure setpoint; stabilize slightly above the pressure setpoint
D. stabilize slightly above the pressure setpoint; fluctuate within a few percent of the pressure
setpoint
stabilize slightly above the pressure setpoint; fluctuate within a few percent of the pressure
setpoint
Vessels A and B are identical except that vessel A receives overpressure protection from an installed
safety valve. Vessel B has an installed relief valve. The safety and relief valves have the same
pressure setpoint and design flow rate.
Water is continuously added to each vessel at the same rate (50 percent of the design flow rate of the
safety and relief valves). After vessel pressure reaches the setpoint for each valve, vessel A pressure
will __________; and vessel B pressure will __________.
A. stabilize slightly above the pressure setpoint; stabilize slightly above the pressure setpoint
B. stabilize slightly above the pressure setpoint; fluctuate within a few percent of the pressure
setpoint
C. fluctuate within a few percent of the pressure setpoint; stabilize slightly above the pressure
setpoint
D. fluctuate within a few percent of the pressure setpoint; fluctuate within a few percent of the
pressure setpoint
fluctuate within a few percent of the pressure setpoint; stabilize slightly above the pressure
setpoint
Refer to the drawing of two identical pressure vessels with identical relief valve protection (see figure
below).
Vessel A is completely filled with subcooled water at 80°F and vessel B is in a saturated, two-phase
condition. Both vessels are currently pressurized to 50 psig and isolated.
If both relief valves fully open simultaneously, the faster pressure reduction will initially occur in
vessel _____; and the faster mass loss will initially occur in vessel_____.
A. A; A
B. A; B
C. B; A
D. B; B
A; A
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 6 gpm. The tank is
protected by two relief valves that discharge to the atmosphere. The relief valves have the following
characteristics:
* Relief valve A opening setpoint is 200 psig with an accumulation of 1.5 percent.
* Relief valve B opening setpoint is 200 psig with an accumulation of 3.0 percent.
* Each valve has linear flow rate characteristics and a maximum discharge flow rate of 6 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
With the PDP running continuously, what will be the discharge flow rates of the relief valves when
tank pressure stabilizes?
Relief
Valve A
Relief
Valve B
A. 1 gpm 5 gpm
B. 2 gpm 4 gpm
C. 3 gpm 3 gpm
D. 4 gpm 2 gpm
4 gpm 2 gpm
A completely full water tank is being hydrostatically tested to 180 psig using a positive displacement
pump (PDP) with a smooth and constant discharge flow rate of 6 gpm. The tank is protected by two
relief valves that discharge to the atmosphere. The relief valves have the following characteristics:
* Relief valve A opening setpoint is 180 psig with an accumulation of 5 percent.
* Relief valve B opening setpoint is 200 psig with an accumulation of 5 percent.
* Each relief valve has linear flow rate characteristics and a maximum flow rate of 4 gpm.
The PDP is inadvertently left running when tank pressure reaches 180 psig.
With the PDP still running, at what pressure will the tank stabilize?
A. 190 psig
B. 195 psig
C. 205 psig
D. 210 psig
205 psig
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 4 gpm. The tank is
protected by a relief valve that discharges to the atmosphere. The relief valve has the following
characteristics:
* The opening setpoint is 200 psig with an accumulation of 5 percent.
* The valve has linear flow characteristics and a maximum rated flow rate of 8 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
With the PDP still running, at what pressure will the tank stabilize?
A. 190 psig
B. 195 psig
C. 205 psig
D. 210 psig
205 psig
A completely full water storage tank is being hydrostatically tested to 300 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 4 gpm. The tank is
protected by a relief valve that discharges to the atmosphere. The relief valve has the following
characteristics:
* The relief valve opening setpoint is 300 psig with an accumulation of 5 percent.
* The relief valve has linear flow characteristics and a maximum rated flow rate of 6 gpm.
The PDP is inadvertently left running when tank pressure reaches 300 psig.
With the PDP still running, at what pressure will the tank stabilize?
A. 305 psig
B. 310 psig
C. 315 psig
D. 320 psig
310 psig
A cooling water system uses a conventional relief valve (not pilot-operated) with a bench-tested
setpoint of 60 psig. The relief valve discharges to a collection tank that is maintained at 5 psig. At
what system pressure will the relief valve begin to open?
A. 55 psig
B. 60 psig
C. 65 psig
D. 80 psig
65 psig
A completely full water storage tank is being hydrostatically tested to 200 psig using a positive
displacement pump (PDP) with a smooth and constant discharge flow rate of 6 gpm. The tank is
protected by two relief valves that discharge to the atmosphere. The relief valves have the following
characteristics:
* Relief valve A opening setpoint is 200 psig with an accumulation of 3.0 percent.
* Relief valve B opening setpoint is 200 psig with an accumulation of 1.5 percent.
* Each valve has linear flow rate characteristics and a maximum discharge flow rate of 9 gpm.
The PDP is inadvertently left running when tank pressure reaches 200 psig.
With the PDP running continuously, what will be the discharge flow rates of the relief valves when
tank pressure stabilizes?
Relief
Valve A
Relief
Valve B
A. 2 gpm 4 gpm
B. 3 gpm 6 gpm
C. 4 gpm 2 gpm
D. 6 gpm 3 gpm
2 gpm 4 gpm
A cooling water system uses a conventional relief valve (not pilot-operated) with a bench-tested
setpoint of 45 psig. The relief valve discharges to a collection tank that is maintained at 5 psi above
atmospheric pressure. At what system pressure will the relief valve begin to open?
A. 40 psig
B. 45 psig
C. 50 psig
D. 65 psig
50 psig
In a comparison between a globe valve and a gate valve in the same water system application, the gate
valve has a __________ pressure drop when fully open and is the __________ choice for throttling.
A. higher; better
B. lower; better
C. higher; poorer
D. lower; poorer
lower; poorer
Refer to the drawing of a lube oil heat exchanger (see figure below).
If a cooling water outlet valve is partially closed from the full open position, heat exchanger cooling
water pressure upstream of the valve will __________; and the temperature of the lube oil exiting the
heat exchanger will __________.
A. increase; decrease
B. increase; increase
C. decrease; decrease
D. decrease; increase
increase; increase
Consider a 3-inch gate valve and a 3-inch globe valve in separate but identical operating water
systems. If both valves are fully open, the gate valve will produce the __________ head loss and the
__________ flow rate.
A. smaller; larger
B. larger; smaller
C. smaller; smaller
D. larger; larger
smaller; larger
Which one of the following statements describes the flow rate characteristics of a typical gate valve in
an operating water system?
A. The first 25 percent of valve disk travel in the open direction will produce a smaller change in flow
rate than the last 25 percent of valve disk travel.
B. The first 25 percent of valve disk travel in the open direction will produce a greater change in flow
rate than the last 25 percent of valve disk travel.
C. The first 25 percent of valve disk travel in the open direction will produce approximately the same
change in flow rate as the last 25 percent of valve disk travel.
D. A gate valve that has been opened to 25 percent of valve disk travel will result in approximately 25
percent of full flow rate.
The first 25 percent of valve disk travel in the open direction will produce a greater change in flow
rate than the last 25 percent of valve disk travel.
Which one of the following statements describes the flow rate characteristics of a typical globe valve
in an operating water system?
A. The first 25 percent of valve disk travel in the open direction will produce a smaller increase in
flow rate than the last 25 percent of valve disk travel.
B. The first 25 percent of valve disk travel in the open direction will produce a greater increase in
flow rate than the last 25 percent of valve disk travel.
C. The first 25 percent of valve disk travel in the open direction will produce approximately the same
increase in flow rate as the last 25 percent of valve disk travel.
D. A globe valve that has been opened to 25 percent of valve disk travel will result in approximately
25 percent of full flow rate.
The first 25 percent of valve disk travel in the open direction will produce a greater increase in
flow rate than the last 25 percent of valve disk travel.
A control valve is most likely to experience cavitation when the valve is almost fully __________
because of a relatively __________ pressure drop across the valve seat.
A. open; large
B. open; small
C. closed; large
D. closed; small
closed; large
Which one of the following statements describes the throttling characteristics of a typical globe valve?
A. The first third of valve disk travel in the open direction will result in approximately one-third of
full flow rate.
B. The first third of valve disk travel in the open direction will produce a smaller increase in flow rate
than the last third of valve disk travel.
C. The first third of valve disk travel in the open direction will produce a greater increase in flow rate
than the last third of valve disk travel.
D. The first two-thirds of valve disk travel in the open direction will produce approximately the same
increase in flow rate as the last third of valve disk travel.
The first third of valve disk travel in the open direction will produce a greater increase in flow rate
than the last third of valve disk travel.
Refer to the drawing of a cooling water system in which both centrifugal pumps A and B are operating
(see figure below).
An operator stops pump B, but the pump B check valve fails to close. In comparison to normal
operation with only pump A running, operation with the failed pump B check valve will result in pump
A flow rate being __________ than normal; and heat exchanger flow rate being __________ than
normal.
A. higher; higher
B. higher; lower
C. lower; higher
D. lower; lower
higher; lower
Which one of the following types of similarly sized valves in an operating water system produces the
least frictional head loss when fully open?
A. Ball
B. Globe
C. Butterfly
D. Swing check
Ball
Refer to the centrifugal pump operating curve with two system head loss curves (see figure below).
The curves apply to a closed cooling water system using one single-speed centrifugal pump
discharging through a typical flow control valve.
The system curves are shown for two flow control valve positions–25 percent open and 100 percent
open. The pump is currently operating with the flow control valve 25 percent open, resulting in a
pump flow rate of 800 gpm.
If the flow control valve is subsequently fully opened, pump flow rate through the valve will be
approximately…
A. 400 gpm.
B. 1,200 gpm.
C. 1,600 gpm.
D. 3,200 gpm.
1,200 gpm.
Consider a 6-inch globe valve and a 6-inch gate valve in the same water system application. Typically,
the valve that requires the most linear disk travel from fully closed to fully open is the __________
valve; and the valve that produces the smallest pressure drop when fully open is the __________
valve.
A. gate; gate
B. gate; globe
C. globe; gate
D. globe; globe
gate; gate
Subcooled water was flowing through a throttled valve with the following initial parameters:
Inlet pressure = 60 psia
Outlet pressure = 50 psia
Flow rate = 800 gpm
The valve was opened fully and the following parameters currently exist:
Inlet pressure = 60 psia
Outlet pressure = 55 psia
What is the approximate flow rate through the fully open valve?
A. 400 gpm
B. 566 gpm
C. 635 gpm
D. Cannot be determined without additional information.
Cannot be determined without additional information.
Subcooled water is flowing through a throttle valve in an open system. The initial steady-state
conditions for the throttle valve are as follows:
Inlet pressure = 60 psia
Outlet pressure = 44 psia
Flow rate = 800 gpm
Four hours later, the current steady-state conditions for the throttle valve are as follows:
Inlet pressure = 63 psia
Outlet pressure = 54 psia
Flow rate = 600 gpm
Which one of the following could be responsible for the difference between the initial and current
conditions for the throttle valve?
A. The throttle valve was opened more.
B. The throttle valve was closed more.
C. Another valve, located upstream of the throttle valve, was partially closed.
D. Another valve, located downstream of the throttle valve, was partially closed.
Another valve, located downstream of the throttle valve, was partially closed.
Subcooled water is flowing through a throttled valve in an open system. The initial steady-state
conditions for the throttled valve are as follows:
Inlet pressure = 60 psia
Outlet pressure = 44 psia
Flow rate = 800 gpm
After four hours, the current steady-state conditions for the throttled valve are as follows:
Inlet pressure = 62 psia
Outlet pressure = 40 psia
Flow rate = 600 gpm
Which one of the following could be responsible for the difference between the initial and current
steady-state conditions for the throttled valve?
A. The throttled valve was opened more.
B. The throttled valve was closed more.
C. Another valve, located upstream of the throttled valve, was partially closed.
D. Another valve, located downstream of the throttled valve, was partially closed.
The throttled valve was closed more.
Refer to the drawing of an operating cooling water system (see figure below) in which valves A and B
are identical. Valve A is one-half open and valve B is fully open. If valve A is opened fully, the
differential pressure (D/P) across valve B will…
A. increase by the same amount as the absolute change in D/P across valve A.
B. increase by an amount less than the absolute change in D/P across valve A.
C. decrease by the same amount as the absolute change in D/P across valve A.
D. decrease by an amount less than the absolute change in D/P across valve A.
increase by an amount less than the absolute change in D/P across valve A.
Consider a 6-inch globe valve and a 6-inch gate valve in the same water system application. The
valve that typically requires the least linear travel of the disk from fully closed to fully open is the
__________ valve; and the valve that produces the greatest pressure drop when fully open is the
__________ valve.
A. gate; gate
B. gate; globe
C. globe; gate
D. globe; globe
globe; globe
Subcooled water is flowing through a throttle valve in an open system. The initial steady-state
conditions for the throttle valve are as follows:
Inlet pressure = 60 psia
Outlet pressure = 44 psia
Flow rate = 800 gpm
Four hours later, the current steady-state conditions for the throttle valve are as follows:
Inlet pressure = 51 psia
Outlet pressure = 42 psia
Flow rate = 600 gpm
Which one of the following could be responsible for the difference between the initial and current
conditions for the throttle valve?
A. The throttle valve was opened more.
B. The throttle valve was closed more.
C. Another valve, located upstream of the throttle valve, was partially closed.
D. Another valve, located downstream of the throttle valve, was partially closed.
Another valve, located upstream of the throttle valve, was partially closed.
Subcooled water was initially flowing through a throttled valve with the following parameters:
Inlet pressure = 70 psia
Outlet pressure = 60 psia
Flow rate = 600 gpm
The valve was then opened fully, and the following parameters currently exist:
Inlet pressure = 60 psia
Outlet pressure = 55 psia
What is the current flow rate through the fully open valve?
A. 424 gpm
B. 848 gpm
C. 1,200 gpm
D. Cannot be determined without additional information.
Cannot be determined without additional information.
Subcooled water is flowing through a throttle valve in an open system. The initial steady-state
conditions for the throttle valve are as follows:
Inlet pressure = 60 psia
Outlet pressure = 44 psia
Flow rate = 800 gpm
After four hours, the current steady-state conditions for the throttle valve are as follows:
Inlet pressure = 58 psia
Outlet pressure = 46 psia
Flow rate = 1,000 gpm
Which one of the following could be responsible for the difference between the initial and current
steady-state conditions for the throttle valve?
A. The throttle valve was closed more.
B. The throttle valve was opened more.
C. Another valve, located upstream of the throttle valve, was opened more.
D. Another valve, located downstream of the throttle valve, was opened more.
The throttle valve was opened more.
Refer to the drawing of an open system with subcooled water flowing through valves A, B, C and D
(see figure below). All valves are initially 50 percent open. The inlet pressure to valve A is constant
at 60 psia.
The initial steady-state inlet and outlet pressures for valve B are as follows:
Inlet pressure = 50 psia
Outlet pressure = 35 psia
After a single valve operation, the current steady-state inlet and outlet pressures for valve B are as
follows:
Inlet pressure = 48 psia
Outlet pressure = 36 psia
Which one of the following valve operations could be responsible for the difference between the initial
and current steady-state inlet and outlet pressures for valve B?
A. Valve A was opened more.
B. Valve B was closed more.
C. Valve C was closed more.
D. Valve D was opened more.
Valve D was opened more.
Refer to the drawing of an operating cooling water system (see figure below) in which valve A is
one-half open. Currently, the centrifugal pump is providing a system flow rate of 600 gpm.
If valve A is opened further, until system flow rate is 800 gpm, the differential pressure across valve A
will __________; and the differential pressure across the heat exchanger will __________.
A. decrease; decrease
B. decrease; increase
C. increase; decrease
D. increase; increase
decrease; increase
Refer to the drawing of a spring-loaded air-operated valve (see figure below).
Upon a loss of air pressure, this valve will…
A. go to the fully open position.
B. remain at the current position.
C. go to the fully closed position.
D. go to the midposition.
go to the fully closed position.
Refer to the drawing of a spring-loaded air-operated valve (see figure below) in which the solenoid is
shown energized.
Which one of the following will be the final valve position following a loss of electrical power to the
solenoid?
A. Midposition
B. Closed
C. As is
D. Open
Closed
Refer to the drawing of a hydraulically-operated valve that is shown in a throttled position (see figure
below).
Select the final position of this valve following a loss of hydraulic system pressure.
A. Fully open
B. As is
C. Fully closed
D. Midposition
Fully open
Refer to the drawing of a spring-loaded air-operated valve shown in a throttled position (see figure
below).
The figure currently depicts normal air supply pressure and an energized solenoid. What will be the
valve position following a loss of electrical power to the solenoid?
A. As is
B. More open
C. More closed
D. Varies with system flow
More open
How will a typical motor-operated valve respond to a loss of electrical power to the valve actuator?
A. Open fully
B. Close fully
C. Remain as is
D. Move to 50 percent open
Remain as is
Refer to the drawing of a spring-loaded air-operated valve shown in a throttled position (see figure
below).
Which one of the following will be the valve position following a reduction in air pressure to the valve
actuator caused by a leaking air connection at the valve?
A. Original position
B. More closed
C. More open
D. Varies with system flow
More closed
Refer to the drawing of a pneumatically-operated valve (see figure below). The valve actuator may
be shown with or without air pressure applied to it.
Which one of the following describes the type of valve shown, and the fail position on loss of air to the
actuator?
Valve
Type
Fail
Position
A. Gate Open
B. Gate Closed
C. Globe Open
D. Globe Closed
Globe Open
Refer to the drawing of four air-operated valves (see figure below). Note: The valve actuators may
be shown with or without air pressure applied.
Given:
* The direction of system flow is from left to right when the valves are open.
* The internal components for each valve are identical except for the orientation of the valve disk
and seat.
* The valve actuators exert the same force on the attached valve stem for a given applied air
pressure.
If each actuator is vented, which valve disk will remain closed with the most force?
A. A.
B. B.
C. C.
D. D.
C.
Refer to the drawing of four air-operated valves (see figure below). The valve actuators may be
shown with or without air pressure applied.
Which valves are currently shown in their failed (i.e., no air pressure applied to the actuator) positions?
A. A and B
B. B and C
C. C and D
D. D and A
B and C
Refer to the drawing of a pneumatically-operated valve (see figure below). The valve actuator may
be shown with or without applied air pressure.
Which one of the following describes the type of valve shown, and the valve’s fail position on loss of
air to the actuator?
Valve
Type
Fail
Position
A. Ball Open
B. Ball Closed
C. Globe Open
D. Globe Closed
Globe Closed
An operator attempts to close a fully-open upright manual gate valve to isolate a pump in a cooling
water system that has been cooled down for maintenance. However, the operator is unable to rotate
the handwheel in the close direction.
Which one of the following could cause this condition?
A. A hydraulic lock has developed under the valve disk.
B. A hydraulic lock has developed in the valve bonnet between the valve disk and the packing gland.
C. The two halves of the valve disk have expanded and are jammed against the valve seats.
D. The valve disk has jammed against its backseat by the difference in the thermal contraction of the
stem and the bonnet.
The valve disk has jammed against its backseat by the difference in the thermal contraction of the
stem and the bonnet.
When manually positioning a motor-operated valve, why must care be taken to avoid using excessive
valve seating/backseating force?
A. The valve may bind during subsequent operation.
B. The valve stem limit switch settings may become inaccurate.
C. The clutch may not reengage the valve motor when required.
D. The stem position may no longer be an accurate indicator of valve position.
The valve may bind during subsequent operation.
After an adjustment of the packing gland on a valve that had a minor packing leak, an operator
attempts to operate the valve, but finds the valve is stuck. What is the most probable cause?
A. The disk separated from the valve stem as a result of overtightening the packing gland.
B. The operator placed the valve in the wrong position for adjusting the packing gland.
C. The valve was overtorqued in the closed direction during the packing gland adjustment.
D. The maintenance technician overtightened the packing gland, causing the stem to bind.
The maintenance technician overtightened the packing gland, causing the stem to bind.
An adjustment has just been completed on the packing gland of a motor-operated gate valve to stop a
minor stem leak. Which one of the following can occur if the technician overtightened the packing
gland?
A. Decreased cooling flow to the valve internals.
B. Separation of the valve disk from the valve stem.
C. Misalignment of the valve position limit switches.
D. Increased stroke time from fully open to fully closed.
Increased stroke time from fully open to fully closed.
Which one of the following describes the function and use of the backseat on a manual valve?
A. Removes pressure from the packing/stuffing box and is typically used to isolate the stuffing box
for valve repacking.
B. Removes pressure from the packing/stuffing box and is typically used when needed to isolate
packing leakage.
C. Acts as a backup in case the primary seat leaks and is typically used during system isolation for
personnel protection.
D. Acts as a backup in case the primary seat leaks and is typically used when needed to prevent the
primary seat from leaking excessively.
Removes pressure from the packing/stuffing box and is typically used when needed to isolate
packing leakage.
When manually closing a motor-operated valve, why must the operator avoid using excessive valve
seating force?
A. The valve may bind and cause the motor to trip on overload during subsequent remote operation.
B. The valve actuator clutch may be damaged and disable subsequent remote operation.
C. The valve stem limit switches may be damaged and cause inaccurate remote valve position
indication.
D. The valve actuator position indicator may be damaged and cause inaccurate local valve position
indication.
The valve may bind and cause the motor to trip on overload during subsequent remote operation.
Refer to the drawing of a water supply pump with two suction sources (see figure below). All
motor-operated valves (MOVs) are currently closed.
Which one of the following MOV interlocks will permit the pump to take a suction on either the
building sump or the water storage tank, while preventing the two sources from being
cross-connected?
A. Neither MOV-1 nor MOV-2 can be opened unless MOV-3 is fully closed.
B. None of the MOVs can be opened unless at least one MOV remains fully closed.
C. None of the MOVs can be opened unless at least two MOVs remain fully closed.
D. Neither MOV-1 nor MOV-2 can be opened unless the other source MOV is fully closed.
Neither MOV-1 nor MOV-2 can be opened unless the other source MOV is fully closed.
Refer to the drawing of two valves used in a high temperature water system (see figure below). Both
valves are currently closed, as shown in the figure.
The valve that is more likely to become stuck due to mechanical binding as the valve cools down is
number _____; and the valve that is more likely to become stuck due to a pressure lock as the valve
heats up is number _____.
A. 1; 1
B. 1; 2
C. 2; 1
D. 2; 2
1; 1
After manually positioning a typical motor-operated valve, the valve actuator motor is reengaged by…
A. taking the manual declutch lever to the disengage position.
B. taking the manual declutch lever to the engage position.
C. racking in the valve actuator motor breaker.
D. energizing the valve actuator motor.
energizing the valve actuator motor.
When the manual declutch lever of a motor-operated valve is moved out of the normal position, it
__________ the motor and __________ the handwheel.
A. engages; engages
B. engages; disengages
C. disengages; engages
D. disengages; disengages
disengages; engages
A typical motor-operated valve with a declutch lever is installed in an emergency core cooling system
(ECCS) application. The ECCS actuation signal is designed to energize the valve motor and open the
valve. The valve is currently open, but being manually/locally closed by a technician as required by a
surveillance test procedure. The declutch lever has been operated and released, and the valve is being
closed by operation of the valve handwheel.
If an ECCS actuation signal is received, how will the valve be affected?
A. The handwheel will disengage and the valve will automatically open.
B. The handwheel will disengage and the valve will remain in the current position.
C. The handwheel will remain engaged and the valve will automatically open.
D. The handwheel will remain engaged and the technician can continue to close the valve.
The handwheel will disengage and the valve will automatically open.
A surveillance test procedure is being performed on a typical motor-operated valve (MOV) with a
declutch lever that is used in an emergency core cooling system (ECCS) application. The declutch
lever has been operated and released, and the valve is being manually/locally opened by a technician.
The MOV breaker is closed as required by the surveillance test procedure. During operation of the
valve handwheel, an ECCS actuation signal is received that normally energizes the valve motor and
closes the valve.
How will the valve be affected by the actuation signal?
A. The handwheel will disengage and the valve will automatically close.
B. The handwheel will disengage and the valve will remain in the current position.
C. The handwheel will remain engaged and the valve will automatically close.
D. The handwheel will remain engaged and the technician can continue to open the valve.
The handwheel will disengage and the valve will automatically close.
A typical motor-operated valve (MOV) has just been opened from the main control room, and the
breaker for the MOV has been opened. A plant operator has been directed to close the MOV locally
for a surveillance test.
If the operator attempts to turn the MOV handwheel in the clockwise direction without first operating
the declutch lever, which one of the following will occur?
A. The handwheel will turn, but the valve stem will not move.
B. The handwheel will not turn, and the valve stem will not move.
C. The handwheel will turn, and the valve stem will move toward the closed position because the
clutch is automatically engaged when the handwheel is turned.
D. The handwheel will turn, and the valve stem will move toward the closed position because the
clutch is automatically engaged when the breaker is opened.
The handwheel will turn, but the valve stem will not move.
Which one of the following types of similarly sized valves requires the most manual valve stem
rotation to move the valve from fully open to fully closed? (Assume that each valve has a non-rising
stem.)
A. Ball
B. Gate
C. Plug
D. Butterfly
Gate
A stop check valve is a type of check valve that…
A. cannot be shut remotely.
B. can be used to prevent flow in both directions.
C. contains both a gate valve disk and a check valve disk.
D. can be opened manually to allow flow in both directions.
can be used to prevent flow in both directions.
Which one of the following valves is used to control the direction of fluid flow and prevent backflow
in a system?
A. Safety valve
B. Relief valve
C. Divert valve
D. Check valve
Check valve
Two common types of check valves used in nuclear power plants are…
A. globe and gate.
B. ball and plug.
C. swing and lift.
D. needle and angle.
swing and lift.
A typical check valve is designed to…
A. permit flow in only one direction.
B. prevent system overpressure.
C. isolate system components.
D. perform automatic pump venting.
permit flow in only one direction.
Check valves are normally used to prevent…
A. overpressurization of nonoperating system piping and components.
B. backflow through nonoperating components or flowpaths.
C. pump runout by providing a constant backpressure.
D. pump cavitation by keeping nonoperating systems filled.
backflow through nonoperating components or flowpaths.
Which one of the following is the type of valve used to control the direction of fluid flow through a
system and prevent backflow?
A. Butterfly valve
B. Gate valve
C. Globe valve
D. Check valve
Check valve
To verify that a manual valve in a pressurized water system is closed, the operator should observe
valve position indication and operate the valve handwheel in the…
A. close direction using normal force, and verify there is no substantial handwheel movement.
B. close direction using normal force, then turn the handwheel an additional one-half turn using
additional force if necessary.
C. open direction until flow sounds are heard, then close the valve using normal force until the
handwheel stops moving.
D. open direction until the valve stem moves, then close the valve using normal force until the
handwheel stops moving.
close direction using normal force, and verify there is no substantial handwheel movement.
To verify the position of a fully open manual valve in an operating system, the operator should operate
the valve handwheel…
A. in the open direction until the valve is backseated one-half turn.
B. to fully close the valve, then open the valve to the fully open position.
C. in the closed direction, then open the valve to its previously open position.
D. to open the valve until it touches the backseat, then close the valve to the desired position.
in the closed direction, then open the valve to its previously open position.
Consider a typical gate valve and a typical globe valve in the same water system application. The
globe valve generally has a __________ pressure drop when fully open; and is __________
commonly used for throttling system flow.
A. smaller; less
B. larger; more
C. smaller; more
D. larger; less
larger; more
Gate valves should not be used to throttle fluid flow because…
A. the tortuous flow path through a gate valve body makes flow control difficult.
B. gate valves must be fully opened and backseated to prevent stem leakage.
C. the turbulent flow created by a partially opened gate valve will cause erosion damage to the valve
seat.
D. the large size of the gate valve disk requires an oversized actuator to accurately position the disk.
the turbulent flow created by a partially opened gate valve will cause erosion damage to the valve
seat.
Refer to the drawing of a valve (see figure below).
Which one of the following describes the type of valve shown?
A. Rising-stem globe valve
B. Nonrising-stem globe valve
C. Rising-stem gate valve
D. Nonrising-stem gate valve
Nonrising-stem gate valve
Consider a 3-inch gate valve and a 3-inch globe valve in the same flowing water system application.
If both valves are fully open, the globe valve produces the __________ head loss and the __________
flow rate.
A. larger; larger
B. larger; smaller
C. smaller; larger
D. smaller; smaller
larger; smaller
Which one of the following is a generally accepted method for locally verifying that a manual valve is
fully closed in a depressurized static piping system?
A. Check a downstream flow gauge to be indicating zero flow.
B. Visually observe the valve rising-stem threading to be fully exposed.
C. Attempt to turn the valve handwheel in the close direction and verify no movement.
D. Compare an upstream and downstream pressure gauge to ensure zero differential pressure.
Attempt to turn the valve handwheel in the close direction and verify no movement.
In a comparison between a typical gate valve and a typical globe valve in the same water system
application with both valves fully open, the gate valve has a __________ pressure drop and is
normally used in __________ flow applications.
A. larger; throttling
B. larger; on/off
C. smaller; throttling
D. smaller; on/off
smaller; on/off
To verify a manual valve in an operating system is closed, the operator should observe valve position
indication and operate the valve handwheel in the…
A. open direction at least one full rotation, then close the valve using normal force.
B. open direction until system flow is observed, then close the valve using normal force.
C. close direction using normal force and verify there is no substantial handwheel movement.
D. close direction using normal force, then operate the valve handwheel an additional one-quarter
turn in the close direction.
close direction using normal force and verify there is no substantial handwheel movement.
Which one of the following is a disadvantage associated with using a gate valve, versus a globe valve,
to throttle flow in a cooling water system?
A. The tortuous flow path through a throttled gate valve body makes flow control difficult.
B. A gate valve will experience stem leakage unless it is fully opened and backseated.
C. The turbulent flow created by a throttled gate valve will cause erosion damage to the valve seat.
D. A fully-open gate valve will produce a greater system head loss than a fully-open globe valve.
The turbulent flow created by a throttled gate valve will cause erosion damage to the valve seat.
After an adjustment of the packing gland on a valve that had a minor packing leak, the operator
attempts to operate the valve, but finds that the valve is stuck. What is the most probable cause?
A. The disk separated from the valve stem as a result of overtightening the packing gland.
B. The operator placed the valve in the wrong position for adjusting the packing gland.
C. The valve was overtorqued in the close direction during the packing gland adjustment.
D. The maintenance technician overtightened the packing gland, causing the stem to bind.
The maintenance technician overtightened the packing gland, causing the stem to bind.
Which one of the following is not a generally accepted method for locally verifying that a valve is
open?
A. Observe local flow rate instrumentation.
B. Check the local valve position indicator indicates OPEN.
C. Turn the valve operator in the close direction and verify that some movement occurs.
D. Attempt to turn the valve operator in the open direction and verify that no movement occurs.
Attempt to turn the valve operator in the open direction and verify that no movement occurs.
Why are gate valves generally not used to throttle water flow?
A. Rapid changes in flow direction inside the valve cause a large unrecoverable system head loss.
B. Gate valves experience stem leakage unless they are fully open or fully closed.
C. The turbulent flow created by a partially opened gate valve causes excessive seat and disk wear.
D. Flow rate through a gate valve is not proportional to the differential pressure across the valve.
The turbulent flow created by a partially opened gate valve causes excessive seat and disk wear.
In a comparison between globe valves and gate valves in the same water system application, globe
valves…
A. are less effective at throttling flow.
B. are less effective as pressure regulating valves.
C. produce a smaller pressure decrease when fully open.
D. require less force to open against large differential pressures.
require less force to open against large differential pressures.
In a comparison between gate valves and globe valves in the same water system application, gate
valves…
A. are more effective at throttling flow.
B. are more effective as pressure regulating valves.
C. produce a larger pressure decrease when fully open.
D. require more force to open against large differential pressures.
require more force to open against large differential pressures.
In a comparison between butterfly valves and ball valves, __________ valves are generally more leak-
tight in high pressure applications; and __________ valves generally exhibit the smaller pressure
decrease when fully open.
A. ball; ball
B. ball; butterfly
C. butterfly; ball
D. butterfly; butterfly
ball; ball
A gate valve is generally a poor choice for throttling fluid flow because…
A. the turbulent flow created by a partially opened gate valve can cause extensive damage to the
valve.
B. the tortuous path through a gate valve body can make flow control difficult.
C. excessive stem leakage will result unless the gate valve is fully open or fully closed.
D. the head loss from a throttled gate valve will result in an unacceptable reduction in system flow
rate.
the turbulent flow created by a partially opened gate valve can cause extensive damage to the
valve.
In a comparison between ball valves and butterfly valves in the same water system application, the
valve that typically would allow more leakage when fully closed with a high differential pressure is the
__________ valve; and the valve that typically would cause the greater pressure loss when fully open
is the __________ valve.
A. ball; butterfly
B. ball; ball
C. butterfly; butterfly
D. butterfly; ball
butterfly; butterfly
A typical motor-operated valve has been returned to service following a complete maintenance
overhaul of the valve and actuator. The valve was remotely opened and closed to verify operability.
The measured valve stroke time in each direction was 15 seconds, which is 25 percent longer than
normal.
Which one of the following could have caused the increased stroke time?
A. The valve position limit switches were removed and were not reinstalled.
B. The valve torque limit switches were misadjusted to open at half their normal setpoints.
C. The valve was packed with improved packing material having a lower friction coefficient.
D. The valve stem packing gland was overtightened after the packing material was replaced.
The valve stem packing gland was overtightened after the packing material was replaced.
In a comparison between ball valves and butterfly valves in the same water system application, the
valve that would typically be more leak-tight when fully closed with a high differential pressure is the
__________ valve; and the valve that typically results in the greater pressure decrease when fully open
is the __________ valve.
A. ball; butterfly
B. ball; ball
C. butterfly; butterfly
D. butterfly; ball
butterfly; ball
In a comparison between ball valves and butterfly valves in the same cooling water system
application, the valve that would typically experience the greater seat leakage when fully closed with a
large differential pressure is the __________ valve; and the valve that would typically cause the
smaller head loss when fully open is the __________ valve.
A. ball; butterfly
B. ball; ball
C. butterfly; butterfly
D. butterfly; ball
butterfly; ball
During a local inspection of a manually-operated 12-inch gate valve, the valve stem is observed to
extend outward from the valve handwheel by 1 inch. The entire external valve stem is threaded,
except for a 1-inch section that becomes smooth just before the valve stem enters the packing gland.
Which one of the following describes the position of the gate valve?
A. The valve is fully open, or nearly fully open.
B. The valve is fully closed, or nearly fully closed.
C. The valve may be in any position, because it is a rising stem gate valve.
D. The valve may be in any position, because it is a non-rising stem gate valve.
The valve is fully closed, or nearly fully closed.
A typical motor-operated valve has been returned to service following a complete maintenance
overhaul of the valve and actuator. When the valve was remotely opened and closed to verify
operability, the measured valve stroke time in each direction was 15 seconds, which is shorter than
normal for this valve.
Which one of the following could have caused the shorter stroke time?
A. The valve position limit switches were removed and were not reinstalled.
B. The valve torque limit switches were misadjusted to open at twice their normal setpoints.
C. The valve was packed with improved packing material having a lower friction coefficient.
D. The valve stem packing gland was overtightened after the packing material was replaced.
The valve was packed with improved packing material having a lower friction coefficient.
During a local inspection of a manually operated three-inch gate valve, the valve stem is observed to
be flush with the top of the handwheel. Two inches of unthreaded valve stem is visible between the
handwheel and the packing gland. The handwheel is mounted to the valve body and valve stem such
that the handwheel can be rotated in either direction, but cannot change its axial position.
Which one of the following describes the position of the valve?
A. The valve is fully open or nearly fully open.
B. The valve is fully closed or nearly fully closed.
C. The valve may be in any position because it has a rising stem.
D. The valve may be in any position because it has a non-rising stem.
The valve may be in any position because it has a non-rising stem.
