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Flashcards in Review Deck (70):
1

The earliest control valves used in the industry are:

Manual Globe Valves

2

In liquids, choking occurs as a result of vaporization of the liquid when the static pressure within the valve drops below the vapor pressure of the liquid.

True

3

Which one of the following Flow Meter is used to measure mass flow directly?

Coriolis Flow Meter

4

Which one of the following control valve characteristic is recommended if the control valve pressure drop is constant?

Linear

5

Which one of the following flow meters is limited primarily to water and waste water applications?

Magnetic Flow Meters

6

Another common name for Beta ratio (b) is ______________.

diameter ratio

7

Which one of the following Equation Constant be used, if sizing the control valve for a liquid flow rate in mass units (lb/h or kg/h).

N6

8

The coefficient of discharge (Cd) is the ratio ___________________________ .

of the true flow to the theoretical flow based on Bernoulli's theorm.

9

The control valve size must:

be smaller or same size as the pipe size

10

Which one of the following control valve characteristic is recommended if the control valve pressure drop is increasing DP with increasing load, DP at Maximum load >200% of Minimum load DP?

Quick Opening

11

Valve Sizing Coefficient

Cv

12

Equation constant, if sizing the valve for a flow rate in volumetric units (gpm or m3/h)

N1

13

Compressibility factor

Z

14

Expansion factor

Y

15

Molecular weight

M

16

Mass rate of flow

w

17

Volume rate of flow

q or Q

18

Liquid specific gravity

Gf

19

Piping geometry factor

FP

20

Numerical constant

N

21

Differential pressure flow meters rely on a(n) ______________ in the pipe to cause a differntial pressure between the upstream and down stream.

obstruction

22

Which one of the followinf flow metes are simple,inexpensive and works well with clean liquds and gasses?

orifice plate

23

When cavitation occurs, it is located:

downstream of the vena contracta

24

Which one of the following devices does not collect information about the process variable and its relationship to desired setpoint?

control valve

25

Given that the inside diameter of a pipe is 6.065 inch, then the nominal pipe size is:

6 inch

26

Which of the following statements about control valves is True?

cavitation is more harmful to the valve than flashing

27

When a fluid passes through a control valve, the pressure is lowest:

where the velocity of fluid is highest

28

"Chocked Flow" in a control valve occurs when:

the flow through a valve is at its maximum

29

The Reynold Number Factor (FR) for flow through a control valve is calculated to be 0.7. Hence the flow can be charcterized as:

Transitional Flow

30

If the specific volume of water at a given temperature is known, then the density of water at that temperature:

can be obtained by taking the inverse of the specific volume value

31

For stream flow, the transmitted impulse lines should come off:

the side of the line

32

following pressure profile before and after a control valve in a pipe:

P1 600kPa

P2 250 kPa

Pv 300 kPa Pv is vapor pressure of liquid

Pvc 200 kPa Pvc is pressure at venacontracta



These values indicate that the control valve will experience:

Flashing

33

Which of the following is a valid trim for control valves in the Fisher specification Mangaer software

equal percentage

34

The sound pressure level that is two times more powerful that 50dB is

53 dB

35

A valve currently exhibits cavitation. which of the following does not reduce cavitation?

increase the temperature of the process fluid

36

A valve with flow change with large stem movement at full stem travel best describe a(n) ___________ valve

quick opening

37

Which one of the following control valve characteristic is recommended if the control valve pressure drop is decreasing DP with increasing load, DP at maximum load

Equal Percentage

38

Differential pressure flow meters rely on a(n) ______________ in the pipe to cause a differntial pressure between the upstream and down stream.

obstruction

39

For fluid such as crude petrolium and its liquid products, with vapor pressure _____________ atmospheric pressure at base temperature.

less than or equal to

40

Which one of the following control valve characteristic should be considered where highly varying pressure drop conditions can be expected.

equal percentage

41

Which one of the following control valve characteristic is recommended if the control valve pressure drop is constant?

Linear

42

Which one of the following control valve characteristic is recommended if the control valve pressure drop is increasing DP with increasing load, DP at Maximum load >200% of Minimum load DP?

Quick Opening

43

The Reynolds Number is a function of ____________

flow rate

44

The common rule of thumb used in sizing a modern control valve is

Make the size of the control valve one size smaller than the line size

45

Valves with a(n)__________flow characteristic used on pressure control applications

equal percentage

46

The Bernoulli coefficients are used only when the inlet piping diameter to a valve is equal to the outlet piping diameter

False

47

The calculated deltaPmax value is compared with the actual pressure drop specified in the service conditions, and the greater of these two values is used in the sizing equations

False

48

If the flow rate is m^3/hr and the pressures are pa, then N1 becomes 0.0865

true

49

The most commonly used fitting in control valve installations is the short length concentric reducer

true

50

Which one of the following Equation constant be used, if sizing the control valve for a gas flow rate in volumetric units and only if the specific gravity is known

N7

51

The rate of flow through a valve under stated conditions

Valve Capacity

52

It is the ratio of the magnitude of the output change of a given system or device to the magnitude of the input change that cause the output change

Gain

53

The range through which an input signal be varied, upon reversal of direction, without initiating an observable change in the output signal

Dead Band

54

A servomechanism that is mechanically connected to a moving part of a final control element or its actuator and that automatically adjusts its output to the actuator to maintain a desired position in proportion to the input signal

Positioner

55

A valve trim element used to modulate the flow rate with either linear or rotary motion

Disk

56

the internal components of a valve that modulate the flow of the controlled fluid

Trim

57

The maximum difference in output value for any single input value during a calibration cycle, excluding errors due to dead band

Hysteresis

58

A pneumatic, hydraulic or electrically powered device that supplies force and motion to open close a valve

Actuator

59

The minimum possible change in input required to produce a detectable change in the output when no reversal of the input take place

Resolution

60

The interconnection of process control components such that the information regarding the process variable is continuously fed back to the controller set point to provide continuous, automatic corrections to the process variable

Closed Loop

61

A movable pressure responsive element that transmits force to the piston actuator stem

Piston

62

The portion of the valve that contains the packing box and stem seal and can guide the stem

Bonnet

63

The portion of the rotary shaft control valve assembly corresponding to the valve stem of a globe valve

shaft

64

The part that connects the actuator to the valve stem and transmits motion (force) from the actuator to the valve

Actuator Stem

65

The symmetrical flow controlling member used in the most common varieties of butterfly valves

disk, conventional

66

A part of a valve trim that surrounds the closure member and can provide flow characterization and/or a seating surface.

cage

67

A flexible, pressure responsive element that transmits force to the diaphragm plate and actuator stem.

Diaphragm

68

The portion of a rotary-shaft control valve assembly corresponding to the seat of a globe valve

Seal ring

69

A valve design in which one port is collinear with the valve stem or actuator, and other port is at right angle to the valve stem

Angle valve

70

The most common type of segmented ball control valve

Ball, V-notch