Basic Measurement And Calibration 03 Flashcards
Mass def:
The amount of a substance
Formula for force
Force = mass × acceleration
Weight def :
Force that attracts a body to earth due to gravity
Value of gravity (2)
SI : 9.81 m/s^2
Imperial: 32.2 ft/s^2
Si system unit of force?
Formula?
Newton
Force = kg × m/s^2 = N
Force, in N for 5.6kg?
F = (m) (gravity)
F= (5.60) × (9.81 m/s^2)
F= 54.9 N
Density formula:
P(rho) = mass/vol
Relative density(RD) formula
RD = density of substance/density of water
Lbf is?
Means?
Pound force
1lb = 4.44824 N
1lbm means,?
Stands for?
1 pound mass
1 lb = .453592kg
Formula for pressure
P = F/A. pressure = force ÷ area
SI basic unit of pressure:
Is equal to?
Pascal
1 pascal = 1 N to 1 sq meter
1 kpa =
1000N/ 1 m^2
Master gauges are considered to be _________ because:
Secondary standards because they need periodic calibration against more accurate standard
Standard atmospheric pressure
101.325 kPa
Convert 14.2psi to kpa
14.2 × (101.325 kPa /14.696 psi) = 97.9
Convert 14.2psi to kpa
14.2 × (101.325 kPa /14.696 psi) = 97.9
- Absolute pressure def
- read by
Difference between a perfect vacuum and process pressure
- absolute pressure guage
Gauge pressure def
Read from
Difference between the local atmosphere and processes pressure
- pressure gauge
Atmospheric pressure def
Read by
Is the pressure due to mass of the air above present location
- a barometer
Vacuume pressure
Read by
Lower than local atmospheric
-Can be read down from gauge or up from perfect vacuum
Scalar quantities def:
Are a numerical magnitude only, you don’t need to specify direction
Vector quantities def:
Involve a magnitude and direction
Displacement def:
Quantifies the straight line distance and direction from an objects starting point to its final position
In physics the common way to name a vector is?
Use a single letter with an arrow above it
Primary standard def
Is an instrument calibrated to the national standard, or standard
Based on a known physical phenomenon
Average speed def
Total distance an object travels/ total time it took
Instantaneous speed def:
The speed of an object at a given time or instant
Constant ( or uniform) speed def:
Its symbol?
Is unchanging speed with no acceleration or deceleration
Symbol is s
If an object travels with constant speed, the constant speed is also
The average speed
Difference between average velocity n speed?
- velocity is DISPLACEMENT/ time and has a direction so is avector quality
Speed is a ______ quality
Scalar
Def : Average acceleration is ______
The difference in velocity/ the time it takes for the difference to occur
Average acceleration formula
A = Vr - Vo / t
The standard unit ( formula) for acceleration is
M/s^2
If a pressure unit ends in g that indicates
It is gage pressure
Measured variable is sometimes called
Measurand
Measured variable is sometimes called
Measurand
Lower range value
Lowest value a device is adjusted to measure
Upper range value
The highest value a device is adjusted to measure
Lower range limit
The lowest value a device is capable of measuring
Upper range limit
The highest value that a device can be adjusted to measure
Span def:
The algebraic difference between upper and lower range values
Error def:
Difference between indication and ideal value of the measured signal
Error = indication- ideal value
Accuracy def:
The degree of conformity of an indicated value to a recognized ideal or standard value
Zero error def:
Error when the device is operating at the LRV . Ex shows 10 psi but the input is 0
Span error def:
Difference between the actual span and ideal span
Angularity error def:
Increases from LRV to mid and then decreases to URV
Dead band error def:
Range through which an input signal may be varied when reversing direction without initiating an observable change
1 Pascal (Pa) is = _____
1 kPa is _____
1 Newton applied to 1 square meter
1000 N to 1 square meter
In a link n lever system SAZ is
Working toward “pen”
S : span
A : angularity
Z : zero
Def hysteresis ( calibration)
Same input gives different out put
Disadvantages of flapper baffle/ nozzle
- only handle low volume
- “blast effect” as flapper gets closer
What do pilot valves do:
Convert mechanical movement to proportional back pressure
3 categories of pilot valves
1) bleed / non bleed
2) direct acting / reverse
3) single acting / double
A direct acting is normally____
Open
The plug is usually arrow shaped for
Non bleed relays
3 components of pneumatic relays
1) pilot valve
2)pneumatic actuator
3) baffle/nozzle
Pneumatic relays are ____ if an increase in nozzle pressure causes an increase in output pressure
Direct
Are ____ acting if an increase in nozzle pressure causes a decrease in output pressure
Reverse
In pneumatic relays gain is
Amplifcation
What is the industry standard for control pressure
3 to 15 psig
Or 20 to 100 kpa
A moment balance has a _____ and is ____ _____
-Fulcrum
- self balncing
An angle motion has no ____ and therefore works cause:
- fulcrum
Focus that oppose, - lever changes angle across the nozzle
True force balance
Input and output meet head on through direct mechanical means. Gain is determined by diaphragm areas
Linear motion balance
Input moves baffle(flapper)
Output moves nozzle
Force balance
When components reach equilibrium they are very nearly in original position
Control devices that get thier energy from the medium they control are
Pressure regulators
What are the uses of pressure regulators
Services where output pressure varies from 10 to 20 %
- gas services
- fuel gass for burners
- instrument air
Spring force calc on a valve
Fs ( spring rate × travel distance) /
Fd ( downstream pressure × area of diaphragm)
2 kinds of pressure regulators ?
1) pressure reducing : fed downstream side, NO
2) back pressure: fed on pressure side and fights spring NC
What king of pressure regulator can have output pressure regulated by air supply to top of diaphragm?
Remotely adjusted
Regulators:
Symbol shows tap arm on right going into valve
Internal, pressure reducing
Regulators:
Symbol shows tap arm on right going into line
External, pressure reducing
Regulators:
Symbol shows tap arm to left and into valve
Internal, back pressure
Regulators
Symbol shows tap arm to left and into process line
External , back pressure
Verna contracta is
The point in a fluid stream where its at its narrowest and therefore highest velocity
Chart recorder pen color red
Differential pressure
Chart recorder pen color blue
Static pressure
Chart recorder color green
Temp
Chart recorders use helical bourdon tubes because
Greater tip movement ie sensitivity
Chart recorder applications
Ovens
Hydrostatic testing
Remote non powered gas flow measurement
Slope on impulse lines on s chart recorder
1” per foot
Relative density of water at 4 `C?
1.0
Ph20 density of water
1000kg/m,^3
Ph20 density of water ( imperial)
62.4 lb/ft
A pressure transmitter at the bottom of a tank reads 10psi the relative density is 1.19. What is the height?
H = 10psi /(.433 × 1.19) = 19.41 ft
.443 because from ^3 to ^2
Def secondary standard
Calibrated by a primary standard
Def working standard
An instrument used to check and calibrate general instruments
Def traceability
An unbroken chain of comparisons
A manometer is considered a _____ standard
Primary
Pa = Pg + Patm is:
Absolute pressure
P Absolute = Pgage + Patmospheric
How would a diode work for temp
Temp up internal resistance goes down
This is a
Transistor
