Test 4 Flashcards
(118 cards)
1
Q
What material is wrapped around the metallic core of the solenoid?
A
Helical coil of wire of steel or iron
2
Q
T/F A solenoid valve is a combination of two basic functional units: a solenoid and a valve.
A
True
3
Q
How is the flow controlled through a solenoid valve?
A
The solenoid is energized and de-energized utilizing the electromagnetic coil to control the flow of fluid through its valve, offering rapid and precise on/off control
4
Q
Label the parts of the solenoid valve shown below. A
A
Coil solenoid
5
Q
Label the parts of the solenoid valve shown below. B
A
Solenoid Spring
6
Q
Label the parts of the solenoid valve shown below. C
A
Lead Wires
7
Q
Label the parts of the solenoid valve shown below. D
A
Piston
8
Q
Label the parts of the solenoid valve shown below. E
A
Outlet Port
9
Q
Label the parts of the solenoid valve shown below. F
A
Orifice
10
Q
Label the parts of the solenoid valve shown below. G
A
Valve Body
11
Q
Label the parts of the solenoid valve shown below. H
A
Inlet Port
12
Q
Label the parts of the solenoid valve shown below. I
A
Coil Windage
13
Q
This part of the solenoid valve moves either upward or downward to regulate the flow of fluid through the valve.
A
Plunger/Piston/Core
14
Q
This part enables the passage of electrical current from a power supply to the solenoid valve.
A
Lead Wires
15
Q
This part isolates the solenoid from the fluid media.
A
Diaphragm
16
Q
This part prevents the fluid flow when the solenoid valve is in the closed position.
A
Disc
17
Q
A 3/2 solenoid valve has ___ ports (orifices).
A
3
18
Q
A 3/2 solenoid valve has ____ switching states.
A
2
19
Q
The standard of symbols for fluid power were developed by this organization.
A
ISO International Organization of Standardization in collaboration what the IEC International Electrotechnical Commission
20
Q
In a fluid power diagram, each state of the valve is indicated by a _________.
A
Square
21
Q
The symbol represents what type of actuation?
A
Electrical Actuation-Coil
22
Q
The symbol represents what type of actuation?
A
Manual Actuation-Spring
23
Q
Closed ports on a solenoid valve drawing are represented by a(n) ______.
A
“T”
24
Q
For the solenoid valve drawing below answer the following questions This valve is a normally ________ valve.
A
Closed
25
For the solenoid valve drawing below answer the following questions This valve is a ____ way (state) valve.
Two
26
For the solenoid valve drawing below answer the following questions In the normal state, this valve ________ allow flow.
does not
27
For the solenoid valve drawing below answer the following questions The square on the ______ shows the valve in non-energized (normal) position
right
28
The designation of an “E” of a port on a 3-way valve indicates _________.
Exhaust
29
The designation of an “P” of a port on a 3-way valve indicates _________.
Pressure
30
The designation of an “C” of a port on a 3-way valve indicates _________.
Cylinder
31
The three3-way solenoid valve shown is a normally ______ valve.
Open
32
Three way solenoid valves are used primarily on ___________ actuators.
Spring Return
33
A three-way solenoid valve has______ pressure inlet port.
One
34
How many exhaust ports does a three-way valve have?
One
35
A four-way solenoid valve has ____ port(s) for the cylinder (actuator).
2
36
Four-way solenoid valve are used with _______ acting actuators.
Double
37
Actuators that use a four-way solenoid valve with fail ________.
last position
38
Name the type of valve represented by the P&ID symbols
Two-way on/off solenoid valve
39
Name the type of valve represented by the P&ID symbols
Three-way on/off solenoid valve
40
External solenoid valve leakage is attributed to issues with ________.
O-ring seals
41
Name two advantages of using a solenoid valve
Can be remotely operated and have a fast response time
42
Name a disadvantage of using a solenoid valve.
Are sensitive to any fluctuations in input voltage and compared to other types of valves, solenoid valves cannot handle high flow rates
43
T/F Valve accessories are typically mounted directly to the valve.
True
44
What function does the filter, regulator and relief valve provide to the actuator?
They condition, maintain pressure, and protect the actuator from being overpressured.
45
Where are filters typically installed?
Between the source of the power supply and the actuator or positioner most often located immediately upstream of the accessory they are protecting
46
T/F Some actuators cannot operate at the outlet supply pressure provided by the compressed air system.
True
47
What equipment does the relief valve protect from damage?
The outlet body of the regulator and the actuator
48
T/F Limit switches are mounted directly to the actuator or case and connect with the moving stem or shaft.
True
49
Name the two styles of limit switches.
Single pole double throw switch and a double pole throw switch
50
What is a pole?
A component of the switch that is moved by the switch to make or break an electrical connection
51
What is a throw?
The total number of possible electrical connections that can be made by a given pole
52
What is SPDT an acronym for?
Single Pole Double Throw switch
53
A SPDT has ___ set of normally open and ____ set of normally closed contacts
1,1
54
T/F Most limit switches share a “common” terminal between the Normally Closed and Normally Open contacts.
True
55
T/F Limit switches are often coupled to a visual indicator that will locally indicate valve position to operators
True
56
T/F A proximity switch contacts the valve stem or shaft.
False
57
Proximity switches are ____ sensitive to dust, moisture, and oil than limit switches.
less
58
T/F A position transmitter provides a continuous signal of valve position.
True
59
The signal provided by the position transmitter is a(n) ________ signal
analog
60
T/F Valve positioners can transmit actual valve position.
True
61
T/F A valve positioner provides feedback to the controller.
True
62
A(n) _______ loop system provides feedback back to the controller.
Closed
63
Where are valve positioners normally mounted?
On the yolk or top casing of the pneumatic actuator for linear control valves or near the end of the shaft for rotary valves
64
Name the four capabilities that a positioner can provide.
1. Ability to have fine control over a precise process.
2. Increase the speed of response to change in process, allowing for faster loading and venting.
3. Allow for split ranging (one controller for two valves.)
4. Overcome seating friction in rotary valves.
65
T/F The difference between upstream pipeline pressure and downstream pipeline pressure is known as pressure drop or pressure differential.
True
66
The highest velocity and lowest pressure occur immediately downstream of the narrowest restriction and is called the ________.
vena contracta
67
Frictional losses as the fluid passes through the valve or restriction cause the downstream pressure to be less than the upstream pressure and is known as _______.
pressure recovery
68
Cavitation and flashing occur when the liquid pressure decreases below the _______ pressure.
vapor
69
With cavitation, the pressure recovers to a point _____ the vapor pressure.
above
70
In _____ flow, additional increases in pressure drop across the valve do not result in additional flow.
choked
71
T/F The liquid/vapor mixture created by flashing is highly erosive to metal.
True
72
T/F Flashing will first occur at the vena contracta pressure.
True
73
Describe the appearance of metal erosion caused by flashing.
Washed out sections of the plug
74
Gas flow ____ cavitate.
Cannot
75
Identify the following terms on the graph: A
Valve Inlet Pressure P1
76
Identify the following terms on the graph: B
Recovery Region
77
Identify the following terms on the graph: C
Pressure Loss ▲
78
Identify the following terms on the graph: D
Valve Outlet Pressure P2
79
Identify the following terms on the graph: E
Pressure Recovery
80
Identify the following terms on the graph: F
Vena Contracta Pressure
81
The difference between exit pressure P2 and pressure at the vena contracta is called the ______.
Recovery region
82
Provide the equation for pressure recovery and a definition of each term.
FL = √[(P1-P2) / (P1-Pvc)] FL = Pressure Recovery Factor (unitless)
P1 = Absolute fluid pressure upstream of the valve
P2 = Absolute fluid pressure downstream of the valve
Pvc = Absolute fluid pressure at the vena contracta (point of minimum fluid pressure within the valve
83
T/F The style of valve is influential on the pressure recovery factor.
True
84
Describe the sound of cavitation in a pipeline.
A ringing sound
85
Cavitation is a ______ phase occurrence.
Three
86
Describe the appearance of cavitation damage on valve parts and piping.
Erosion and pitting
87
Describe the sound of flashing in a valve
A ‘hissing” sound similar of what sand might sound like if it were flowing through the valve
88
Name the three levels of cavitation.
Incipient, constant and choked
89
This state of cavitation has a steady rumbling sound associated with start of possible valve damage.
Constant
90
As the cavitation index value, σ, ________, the cavitation damage is increasing.
decreases
91
Name a recommendation to eliminate or minimize cavitation.
Flow resistance can be added downstream of the control valve
92
T/F Some valves (i.e. globe) can be equipped with anti-cavitation design features that include special cages that perform pressure drop staging.
True
93
T/F Cavitation can cause damage to equipment in the pipeline system near the valve.
True
94
What impact does high flow velocities cause in gas applications?
Creates turbulence and vibration in liquid applications and high noise levels in gas applications
95
Water hammer is a result of a _______.
pressure surge
96
Name a cause for water hammer.
Open valve suddenly closing
97
Name two long term effects of water hammer.
Pump and flow system damage and ruptured pipes
98
Name a mechanism to reduce the effect of water hammer.
Spring assisted check valves
99
Name the two types of valve leakage.
Fugitive emissions and leakage remaining in the piping systems
100
Name two causes of valve leakage.
Corrosion and wear of valve parts
101
T/F Vapor pressure is not dependent on temperature
False
102
T/F When gas or steam flows through a control valve, noise is generated.
True
103
T/F Noise from a control valve may be loud enough to cause hearing damage to those who are nearby.
True
104
When gas flows past a restriction in the control valve, the velocity _______.
Increases
105
T/F If the pressure drop across the control valve is high enough, the turbulence will generate sound waves which will move down the pipe with some coming through the pipe wall.
True
106
Name the two strategies for reducing control valve noise.
Source control and Path control
107
Define “pressure drop staging” noise reduction.
Instead of taking the entire pressure drop in one step, the pressure drop is divided up into two or more steps
108
Doing something to the valve to make it less noisy is known as ____ control
source
109
T/F Small reductions in velocity have a small effect on reducing valve noise.
False
110
Define “flow division” noise reduction.
Instead of having the flow pass through a single opening, the flow is divided up so that it passes through serveral openings in parallel
111
For the “flow division” noise reduction method, every time you double the number of openings, you reduce the noise by ___dBA.
3
112
T/F Using the smaller opening associated with “flow division” actually shift the noise to higher frequencies.
True
113
Globe control valve using flow division with one stage noise trim can achieve noise reduction of ___dBA noise reduction.
10-15 dba
114
Multiple stage flow dividers can achieve ____ dBA noise reduction.
15-25 dba
115
Name the three types of path control method that can be used to control noise.
Distance, heavy wall pipe and thermal or acoustic insulation
116
Thicker pipe walls attenuate ____ noise as it passes through the pipe wall compared to thinner pipe walls.
more
117
Name a disadvantage of using heavy wall pipe to control noise.
If you rely on heavy wall pipe you must use as far down stream as you want the noise reduction which is a very expensive solution
118
Name a disadvantage of using acoustic insulation to control noise.
The same issue as heavy wall pipe, you must insulate as far downstream as you want the reduced sound pressure which can be prohibitively expensive
