Download Sensor Calibration

51Last Rev.: 25 AUG 08
Sensor Calibration : MIME 3470
Page 1
Grading Sheet
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MIME 3470—Thermal Science Laboratory
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Laboratory №. X
SENSOR CALIBRATION
Students’ Names Section №
POINTS
10
APPEARANCE, ORGANIZATION, ENGLISH, and GRAMMAR
MATHCAD
TURBINE-TYPE METER CALIBRATION CURVE
PRESSURE TRANSDUCER CALIBRATION CURVE
SHEAR BEAM CALIBRATION CURVE
25
25
25
DISCUSSION
CONCLUSIONS
ORIGINAL DATA SHEET
TOTAL
Comments
d
GRADER—
5
5
5
100
SCORE
TOTAL
52Last Rev.: 25 AUG 08
Sensor Calibration : MIME 3470
MIME 3470—Thermal Science Laboratory
~~~~~~~~~~~~~~
Laboratory №. X
SENSOR CALIBRATION
~~~~~~~~~~~~~~
LAB PARTNERS: NAME
NAME
NAME
SECTION
№
EXPERIMENT TIME/DATE:
NAME
NAME
NAME
TIME, DATE
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OBJECTIVE—The objective of this experiment is to familiarize
the student with some common types of sensors used in fluid
engineering applications. The students will construct calibration
curves and determine sensor characteristics.
INTRODUCTION—There are many different sensors used in
fluid engineering: temperature sensors, pressure sensors, flow
meters, and load cells are only a few. The subject of this
experiment is to calibrate some of the sensors that will be used in
later experiments in this class.
1. The Turbine-type Flow Meter
Turbine flow meters are the most
popular way to measure flow
electronically in a wide range of
industries. Inside a turbine meter,
the flow medium engages a vaned
rotor, causing it to rotate at an
angular velocity that is directly
proportional to the flow rate. As
the turbine rotates, an AC voltage
is induced in a magnetic pickup
coil mounted outside the fluid
process. As each turbine blade
passes the base of the pickup coil,
the magnetic flux density is
affected, inducing a voltage pulse.
Schematic of the basic
Each pulse represents a distinct
operation of the turbinevolume of fluid that has been
type flowmeter [1]
displaced through two adjacent
blades. The pulse rate generated is thus a measure of the flow rate. In
theory, this produces a linear relationship between the flow rate and
the pulse rate. In reality, friction in the system requires a minimum
flow for the linear relationship to be approximately true.
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3. Shear-Beam Load Cell
There are many types of
load cells for force
measurement, with the
most common being straingage based. A strain-gage
load cell consists of an
elastic element with mounted strain gages Depending on range
and stiffness requirements, the sensing element can be a
compression/tension member, cantilever-beam, and shear-beam,
among others. In a shear-beam sensor, the elastic member
produces equal tensile and compressive stresses at adjacent
locations on the same surface as shown, allowing the use of
prefabricated planar gage assemblies that incorporate a full bridge
of gages. The gage’s “unit construction” offers many
manufacturing and performance advantages.
Experimental Procedure:
Turbine Meter— The student will be calibrating the turbine meter
against a variable-area flow meter (rotameter). The frequency
output of the turbine meter will be determined by using a
computer-based data acquisition and analysis system to count the
number of cycles over a fixed period of time. Measure the
frequency output of the meter against the flow rate as indicated by
the rotameter. For your report: on one plot, show the measured
flow rates against the frequency readings and determine and plot a
regressed line of the data. This is a calibration curve. The Mathcad
linear regression function is documented below (source Mathcad
Help). The slope of the curve indicates the volume per pulse of the
turbine meter.
2. Pressure Transducer
Check out also the SLOPE and INTERCEPT functions in Mathcad Help
Because of the great variety of conditions, ranges, and materials
for which pressure must be measured, there are many different
types of pressure sensor designs. Often pressure can be converted
to some immediate form, such as displacement. The sensor then
converts this displacement into an electrical output such as
voltage or current. The three most universal types of pressure
transducers of this form are the strain gage, variable capacitance,
and piezoelectric. Off all the pressure sensors, Wheatstone bridge
(strain based) sensors are the most common. All bridge sensors
make use of a stain gage and a diaphragm. When a change in
pressure causes the diaphragm to deflect, a corresponding change
in resistance is induced in the strain gage attached to the
diaphragm. This in turn causes a change in the Wheatstone bridge
balance and voltage output.
Pressure Transducer – The pressure transducer will be calibrated
using a handheld electronic pressure calibrator. The voltage output
of the transducer will be measured against the input pressure. For
your report: on one plot, show the input pressure against the voltage
readings and determine and plot a regressed line of this data. This is a
calibration curve. The Mathcad linear regression function again will
be used. The slope of the curve indicates pressure per voltage
output of the transducer.
Shear-Beam Load Cell – The student will calibrate the load cell
by hanging weights and noting the outputted voltage. For your
report: on one plot, show the weights against the voltage readings
and determine and plot a regressed line of this data. The slope of the
curve indicates force per voltage output of the load cell.
Last Rev.
6/28/2017
Ordered Data, Calculations, & Results
MATHCAD OBJECT--DOUBLE CLICK TO OPEN
Sensor Calibration : MIME 3470
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Last Rev.: 25 AUG 08
DISCUSSION OF RESULTS
Sensor Calibration : MIME 3470
CONCLUSIONS
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Last Rev.: 25 AUG 08
Sensor Calibration : MIME 3470
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DATA SHEET FOR SENSOR CALIBRATION
Time/Date:
___________________
Lab Partners
____________________________
____________________________
____________________________
____________________________
____________________________
____________________________
Turbine Meter:
Rotameter Flow
rate
(gpm)
Frequency, Hz
Pressure, inH20
Voltage, V
Weight, g
Voltage, V
d
d
d
d
d
d
d
d
Pressure Transducer:
d
d
d
d
d
d
d
d
Load Cell:
d
d
d
d
d
d
d
d