review Flashcards
(90 cards)
1
Q
3 Types of Pitot Tubes
A
Conventional
Annubar
Area Averaging
2
Q
A Conventional pitot tube is used in?
A
(L)arge water lines/pipe air flows
(O)pen channel measurements
(W)ater speed/air
3
Q
A Conventional pitot tubes advantages?
LEL
A
Large flows
(E)asy insertion
(L)ittle to no restriction
4
Q
A annubar pitot tube is what?
A
More accurate than conventional
5
Q
A area averaging pitot tube is used where?
A
-Large duct work
-Large flows of low pressure gases
6
Q
What are the screw driver colours?
A
Orange, yellow, green, red, black
7
Q
5 Types of pipe connections
A
Flange
Vena contracta
Radius
Pipe
Corner
8
Q
7 types of electrical pressure elements
A
strain gauge
capacitance
resonance
piezoelectric
optical
magnetic
potentiometric
9
Q
Define range
A
region between 2 limits by stating its upper and lower values
10
Q
Type of solder
A
60/40 tin to lead with a resin core
11
Q
Define span
A
Difference between upper and lower range values
12
Q
4 types of orifice plates?
A
concentric
eccentric
segmental
conditioning
13
Q
How to isolate a manifold?
A
(C)lose high side
(o)pen equalizer
(c)lose low side
14
Q
How to put a manifold back into service
A
open equalizer
open L side
close equalizer
open H side
15
Q
Define bernoullis principle
A
Speed of fluid increases=pressure of fluid decreases.
16
Q
Define cavitation
A
liquid to gas and back again caused by change in pressure(vavle or restriciton)
17
Q
5 smart communication protocols
A
Hart
ARC net
Profibet
World FIP
Foundation Bus
18
Q
Practical Considerations when selecting a flow meter?
A
(Q)antity
(T)emperature of process
(T)ype of process
(O)bstruction of flow
(M)aintenance
(C)ompatibility
(A)ccuracy
(T)urbulance
(C)ontrol
(A)ambient temperature
(P)ressure of process
19
Q
A strain gauges measures what?
A
The deformation of an object when subjected to stress.
20
Q
1 psi = ______kPa
A
6.895kpa
21
Q
1 “H2O=mmHg
A
1.87
22
Q
1 atm=bar
A
1.0135bar
23
Q
1”Hg=”H2O
A
13.61”H2O
24
Q
To determine input value
A
(output value-output LRV/output span) x input span + input LRV
25
To determine output value
(input value-input LRV/input span) x output span + output LRV
26
1 psi="Hg
2.04"Hg
27
1 atm=psi
14.7psi
28
1"H2O=cmH2O
2.54"H2O
29
1 bar=psi
14.5psi
30
4 common pressure scales
(D)differential pressure
(A)bsolute
(V)acuum
(G)auge
31
3 Types of manometers and which one is used in HVAC
U-Tube
Well
Incline (HVAC, detects small pressures in gases)
32
Name 4 types of weirs and their uses
V-notch: small & slow changing flows
Rectangular: High capacity most common
Cipolleti: High capacity
Combination/well: small flows occuring 90% of time
33
What is a weir?
Dam with a notch cut in it that is used to measure large flows in open channels
34
3 main parts of a flume/pharshall
converging section
throat section
diverging section
35
A weir is made of what?
timber
concrete
sheet metal
36
What does a transducer do?
converts one form of energy to another, like pressure to current or vise versa
37
Types of flow transmitters
Differential pressure
Vortex
Turbine
Magnetic
Positive displacement
Variable Area
Coriolis
Ultrasonic
Thermal
38
Flow measurements: Differential pressure can measure: (GASL)
(G)as
(A)ctual flow
(S)team
(L)iquids
39
Flow measurements: orifice works on the principle of what?
Works on Bernoullis principle
Limitations:
40
Pressure
The force exerted over a unit area, p=F/A
41
Relay
Boost output and valve volume
42
Resonance
Causes a wire to vibrate at it's resonant or natural frequency
Changes in pressure = changes in frequency of an oscillating fan
Determined on 1)mass 2) square root of the tension 3) length
Tension is proportional to applied pressure
43
A strain gauges resistance changes when:
stretched, proportional to the pressure applied
44
callibration procedure
1. Obtain Instruction Manual
2. Check for damaged or loose parts making sure everythings tight
3. Make a callibration hook up diagram and hook up your equipment accordingly
4. Apply 0% input and adjust the zero for the proper output
5. Apply 100% input and adjust the span for the proper output
6. Repeat steps 4 & 5 until the zero and span values are correct
7.Check midpoint value for linearity error. If provided, adjust it to correct value, then repeat steps 4 to 7 until correct. If no linearity adjustment is provided, record the linearity error and proceed to step eight.
8. Check for repeadibility and hysteresis errors by applying input values of 0, 25, 50, 75 & 100 in both directions, compare use a table.
45
Direct Acting Relay
As input goes up, output goes up
when speaking relays inputs the back pressure output is the 3-15 psi
46
A Mass flow meter measures what
The rate of flow but compensates for temp and pressure density resulting in a true mass flow reading
47
Positive displacement meter
Won't allow flow if jammed and uses energy from process to operate
48
Variable area flow meter
(P)roportional to the rate of flow
(O)orifice creates a fixed differential pressure
(U)ses a device in response to flow rate
49
Head meter
creates a differential pressure related to velocity (head pressure)
50
Bernoullis principle
if the same water, at the same level goes through pipes of diff sizes that water's velocity will be different in each area
the increase in this speed happens simultaneously with decrease in static presssure
50
turbulent flow
mixing of fluid particles due to bends in a pipe, restrictions, or velocity
51
laminar flow
fluid goes slow and straight causing no turbulence
52
vapour pressure
boiling point of a liquid at a given temp or pressure
53
Capillary action
Liquids cohesive and adhesive forces (meniscus in a manometer)
54
surface tension
Cohesive forces on the surface of a liquid
55
cohesion
allows liquid to resist tensile stress
56
viscosity
fluids resistance to deformation (water=low, oil=high)
57
A High select relay
with 2 or more inputs; a high select relay selects the high pressure value
compares two pressures and selects the higher of the 2
causes the flapper to close the lower input pressure port
58
LVDT
Linear variable differential transformer
59
FQ
Flow Integrator
60
TW
Thermowell
61
FO
fixed restriction orifice
62
PSE
Rupture disk
63
PSV
Pressure saftey valve
64
What does a Integrator/totalizer do and it's purpose
Output is in counts it's purpose is to count a measured quantity
65
A Differential pressure transmitter is used to measure?
low pressure
negative pressure
pressure drop
flow (differential pressure)
level
density
66
Types of Flow transmitters
Vortex
Turbine
Ultrasonic
Magnetic
Thermal
Coriolis
Variable Idea
Positive displacement
67
Types of flow elements
Orifice
Venturi
Pitot tube
Vortex shedding
Turbine flow meter
Ultra sonic flow
Coriolosis
Pressure/temperature correction
Multi-Variale transmitters
Thermal mass flow
68
Orifice Flow meter measures and limitations
liquid and gas
limitations:
(T)urn down
(L)imited low flow measurement
Pressure drop
69
Venturi
Similar to orifice plate but reduces pressure drop
Limitations:
1)limited low flow measurement
2)sensitive to changes in process pressure and temperature
70
Averaging Pitot Tube measures what? and its limitations
Measures average velocity across pipe, good for liquid and steam flow
limitations:
1)(T)urn down
2) (L)ow flow sensitivity
71
Vortex shedding measures what? And its limitations
Measures high flow rates; liquid or steam flow
limitations:
1) minimum flow rate
2) only measures actual flow rate
72
Turbine Flow Meters measures what? and its limitations
Measures air and gas
limitations:
1) require pressure and temp to record mass flow
2) smaller applications
73
Ultrasonic Flow measures what? And its limitations
measures velocity of fluid in closed pipe
limitations:
1) require pressure and temp to record mass flow
74
Coriolis measures what? And its limitations (PENL)
Measures gas flows high accuracy mass flow
limitations:
(P)ressure drop
(E)xpensive to buy and install
(N)ot suitable for low flow and low pressure
(L)imitations in size
75
Multi-variable transmitters
measures mass flow
reduces cost of differential pressure mass flow measurment
used in averaging pitot or vortex
limitations: expensive
76
Thermal Mass Flow
measures gas flow
Great at:
1) mass flow measurement
2)excellent low flow sensitivity
3) excellent turn down
4) low pressure drops
5)easy to install
6)factory callibrated
7cheapest out of all
77
4 types of scales
1)Platform scales (mechanical lever, load cell)
2)Bin scales
3)Truck scales (single draught, double draught, axle weighing)
4)Belt scale(strain gauge, nuclear)
78
Belt scale callibration
1)verify belt speed
2)run belt empty; apply zero
3)apply test weights; apply span
79
Capacity
the maximum weight a scale is capable of measuring
80
Excitation Voltage
voltage applied to the input terminals of electrical bridge circuit
81
Gross weight
total weight of material plus its container
82
leveling
adjustment of weighing something complety horizontal making measurments repeatable if platform moved
83
load cell
output signal proportional to applied force
84
measuring cell
takes lload cell and creates electrical signal
85
net batch out
net point determining how much should be withdrawn
86
net weight
weight of material excluding its container
87
tare
weight of empty container
88
to tare
deducting the wheight of the container
89
A High select relay
with 2 or more inputs; a high select relay selects the high pressure value
compares two pressures and selects the higher of the 2
causes the flapper to close the lower input pressure port
