Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Christina Smith
April 9, 2012
Orifice Plate Test Results
A test was conducted on the orifice plate and the pressure sensor in order to test the consistency
of the orifice place and its compatibility with the pressure sensor.
Setup
Using the flow meter setup from Project 12055, a labview program (Program is available on
Edge under the Orifice Plate and Pressure Sensor section of the Test Plan) was created to read
and record flow meter readings. The same program also read and recorded data from our chosen
pressure sensor (MB-LPS1-01-200U5R).
Picture 1 shows the setup of the flow meter (Alicat
Scientific M-50SLPM-D-30PSIA/5M). The male to
female adapter is screwed into the left side of the flow
meter. The yellow tubing fixed to the adapter is
connected to the clear hose, which is shown attached to
the orifice plate in Picture 3.
Picture 1
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Picture 2 shows the setup of the right side of the flow
meter. The flexible tubing is inserted into the smaller left
hole. The other end of the tubing is to the vacuum pump.
Picture 2
Picture 3 shows the setup of the orifice plate. The clear
tubing on the right side of the orifice plate is attached to
the flow meter shown in Picture 1. The two small clear
tubes attached to the pressure taps are attached to the
pressure sensor circuitry. A cigarette is inserted into the
left side of the orifice plate.
Picture 3
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Pictures 4 and 5 show the entire setup of the experiment (the pressure sensor is not hooked up in these
pictures)
Picture 4
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Picture 5
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Pictures 6 and 7 show the setup for the DAQ. AN NI-6008 DAQ was used, which I integrated
within the Labview program for the test.
Picture 6
Picture 7
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Procedure
After zeroing the flow meter and the vacuum pump, the labview program was started. The flow
meter was increased by approximately 0.25 L/min every 15-20 seconds, until it reached 4.25
L/min. This process was repeated five times.
Results and Analysis
The labivew program outputs the flow meter data in mL/s, so no conversion is needed. The
pressure sensor data is outputted as a voltage drop. In order to convert the voltage to a pressure
drop, the following data was taken from the pressure sensor data sheet:
Figure 1
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Figure 1 shows the full scale of our
selected pressure sensor to be 0-2” H20.
The ratiometric output of this series of
pressure sensor provides a maximum
output voltage of 4.5V, as stated in the
general description on the data sheet.
Using this information, as well as the
linear relationship provided in Figure 2,
we can create a linear relationship for
out specific pressure sensor. Taking the
inverse of this relationship gives us the
graph shown in Figure 3. The equation
y = 0.4938x – 0.2222 represents the
pressure change as a function of voltage
output. Using this conversion factor, we
were able to create the graph shown in
Figure 4.
Figure 2
Figure 3
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Figure 4
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Trial
Equation
R2
1
y = 0.00015653x2 + 0.00257933x - 0.00168944
0.99773962
2
y = 0.00015737x2 + 0.00270556x - 0.00574824
0.99898271
3
y = 0.00015972x2 + 0.00238248x + 0.00010354
0.99846106
4
y = 0.00015960x2 + 0.00239955x + 0.00093494
0.99962162
5
y = 0.00015653x2 + 0.00257933x - 0.00168944
0.99773962
Calibrated Curve
y = 0.00015833x2 + 0.00251597x - 0.00114353
0.99885096
Theoretical Curve
y = 0.00035559x2 - 0.00135681x + 0.00362593
0.99999084
Drilled Out
y = 0.00024226x2 + 0.00311794x + 0.00044809
0.99962256
Figure 5
Figure 5 shows the best-fit equation and R2 value for each of the respective trials, as well as the
theoretical curve, final calibration curve, and drilled out curve. The calibration curve was derived
as an average of the best fit curves for the five trials.
Many of the people surveyed about the orifice plate stated that they experience a lot of resistance
when smoking through the device. In order to try and reduce this, the team drilled out the end of
the orifice plate. Figure 6 shows the schematics of the orifice plate before and after being drilled
out. A new test was then performed on the optimized orifice plate, the results of which can be
seen in Figure 4.
The predicted pressure given by the theoretical curve in Figure 4 was shown to be much higher
than the actual pressure drop recorded in our original trials. This could have been because of
numerous step downs present in the tubing used in our experiment. The tubing connecting the
vacuum pump to the flow meter was not tightly fitted into the input hole, and we could likely
benefit from a tighter seal in the future.
Multidisciplinary Senior Design
P12056 – Ergonomic Improvements to Personal Smoke Monitoring Device
Figure 6
Conclusions
Overall, the orifice plate proved that it is capable of producing consistent data. Each of the five
trials showed very little variation, with minimal outliers. The calibration curve derived from this
experiment can be used in the future to predict a pressure drop from a given flow rate.