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PressureMeasurementExperimentforAhmad.docxPressure Measurement Experiment
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Abstract
Pressure measurement is an important aspect of engineering. Many engineering devices are controlled using pressure knobs. There are different devices that can be used for purposes of pressure measurement. In our experiment, we employed the use of three devices namely variable reluctance transducer, single –tube manometer and bourdon tube. The tube manometer was essential for calibration purposes because it provided the standard values that were used for comparison with pressure measured in reluctance transducer and bourdon tube. The comparison of the devices indicated that there were minimal errors. The highest error recorded for bourdon tube was 3.55% and the lowest error was 0.66%. For the case of variable reluctance transducer, the highest error that was recorded was 5.05% and the lowest error was 3.05%. Most importantly, we noted that the accuracy was high due to low percentage errors that were recorded. The errors in measurement can be attributed to human mistakes and also differences in calibration of the pressure measuring devices.
Introduction
When a normal force is exerted on the area of a fluid the product will be pressure. There are different devices that are employed for purposes of pressure measurement. In this case, a force on elastic element is produced resulting to displacement. In this case the displacement results from mechanical electrical systems. Manometer is an important device that measures pressure by using the column for the height of liquid. In our experiment, we used different devices for purposes of pressure measurement. They include: variable reluctance transducer, single-tube manometer and bourdon tube. Equations 1,2 and 3 are used to calculate pressure, vacuum pressure and gauge pressure respectively. For standard pressure measurement, equation 4 is applicable.
Description of Work/ Procedure
We started the experiment by locating the apparatus near the electrical outlet whereby the hand bicycle pump was the source of air for the experiment. The plugging of two readout devices was done for the transducers in and then zeroed. The hose from the pump was connected properly and appropriate hoses were also connected to manometers. The pressure measurement was started and through the pumping apparatus reservoir using bourdon gauge as reference to a maximum of 20 psi. The validyne display and span strain-gauge meter were set to read 14.73 psi. The pressure was decreased from 15 psi by 1 psi by the use of the manual relief valve and then the readings were recorded for at least 10 points for all the instrument
Results and Discussion
Table 1 presents comparison for measurement of two pressure devices and the standard measurement that employed the use of manometer. In this case, the highest error that was recorded for variable reluctance transducer was 5.06% and the lowest error was 3.05%. For the case of Bourdon tube device, the highest error that was recorded was 3.55% while the lowest error that was recorded was 0.66%.
Table 1: comparison
|
Error for Bourdon Tube |
Error for Variable Reluctance transducer |
Variable Reluctance Transducer (psi) |
Bourdon Tube( psi) |
Standard (psi) |
|
2.723488889 |
3.046666667 |
15 |
15.05 |
15.47136079 |
|
2.133004746 |
3.375322034 |
14 |
14.18 |
14.48905217 |
|
1.840057664 |
3.400510949 |
13 |
13.21 |
13.45762812 |
|
1.418003953 |
3.429881423 |
12 |
12.25 |
12.42620406 |
|
0.656265517 |
3.464568966 |
11 |
11.32 |
11.39478001 |
|
0.110755869 |
4.412206573 |
10 |
10.45 |
10.46158682 |
|
0.429587565 |
5.056062176 |
9 |
9.52 |
9.4792782 |
|
0.729410526 |
4.747602339 |
8 |
8.46 |
8.398738716 |
|
1.529530667 |
4.985733333 |
7 |
7.48 |
7.367314663 |
|
3.550704688 |
4.5615625 |
6 |
6.51 |
6.286775179 |
Figure 1: Bourdon Tube calibration
Figure 2: Variable Reluctance Transducer
Figure 3: Difference in measured pressure
Figure 1 and figure 2 show calibration graphs for Bourdon Tube and Variable Reluctance Transducer devices respectively. In both graphs, the relationship between standard pressure measurement and Bourdon Tube and Variable Reluctance Transducer pressure is a straight line. The slopes of the line graphs are 1.0702 and 1.0156 for figures 1 and 2 respectively. Figure 3 shows line graphs for pressure difference versus standard pressure. In this case, the pressure difference is not proportional to the standard pressure hence the need for best fit line.
Conclusion
In conclusion, the objectives of the experiment were achieved. We were able to compare the variable reluctance transducer and bourdon tube pressures with standard pressure. The precision of the instruments were high and also the accuracy was high. As a result, the errors recorded were low because there was a slight difference between the standard pressure and pressure measured in the two devices.
Appendix
Table 2
|
Reluctance transducer Difference |
Bourdon difference |
Error for Bourdon Tube |
Error for Var Reluctance transducer |
|
0.471360792 |
0.421360792 |
2.723488889 |
3.046666667 |
|
0.48905217 |
0.30905217 |
2.133004746 |
3.375322034 |
|
0.457628118 |
0.247628118 |
1.840057664 |
3.400510949 |
|
0.426204065 |
0.176204065 |
1.418003953 |
3.429881423 |
|
0.394780012 |
0.074780012 |
0.656265517 |
3.464568966 |
|
0.461586821 |
0.011586821 |
0.110755869 |
4.412206573 |
|
0.4792782 |
0.0407218 |
0.429587565 |
5.056062176 |
|
0.398738716 |
0.061261284 |
0.729410526 |
4.747602339 |
|
0.367314663 |
0.112685337 |
1.529530667 |
4.985733333 |
|
0.286775179 |
0.223224821 |
3.550704688 |
4.5615625 |
Table 3
|
Variable Reluctance Transducer (psi) |
Bourdon Tube( psi) |
Single-Tube Manometer (psi) |
|
15 |
15.05 |
15.47136079 |
|
14 |
14.18 |
14.48905217 |
|
13 |
13.21 |
13.45762812 |
|
12 |
12.25 |
12.42620406 |
|
11 |
11.32 |
11.39478001 |
|
10 |
10.45 |
10.46158682 |
|
9 |
9.52 |
9.4792782 |
|
8 |
8.46 |
8.398738716 |
|
7 |
7.48 |
7.367314663 |
|
6 |
6.51 |
6.286775179 |
Bourdon Tube calibration
Single-Tube Manometer (psi) 15.05 14.18 13.21 12.25 11.32 10.45 9.52 8.4600000000000009 7.48 6.51 15.471360792133671 14.489052170410899 13.457628117601987 12.426204064793076 11.394780011984164 10.461586821347531 9.4792781996247584 8.3987387157297082 7.367314662920796 6.2867751790257458Bourdon Tube (Psi)
Standard (psi)
Variable Reluctance Transducer
Variable Reluctance Transducer (Psi) 15 14 13 12 11 10 9 8 7 6 15.471360792133671 14.489052170410899 13.4576281 17601987 12.426204064793076 11.394780011984164 10.461586821347531 9.4792781996247584 8.3987387157297082 7.367314662920796 6.2867751790257458Variable Reluctance Transducer (Psi)
Standard Pressure (psi)
Difference in measured pressure
Reluctance transducer 15.471360792133671 14.489052170410899 13.457628117601987 12.426204064793076 11.394780011984164 10.461586821347531 9.4792781996247584 8.3987387157297082 7.367314662920796 6.2867751790257458 0.47136079213367132 0.48905217041089877 0.45762811760198652 0.42620406479307604 0.39478001198416385 0.46158682134753093 0.47927819962475832 0.39873871572970826 0.36731466292079595 0.28677517902574579 Bourdon difference 15.471360792133671 14.489052170410899 13.457628117601987 12.426204064793076 11.394780011984164 10.461586821347531 9.4792781996247584 8.3987387157297082 7.367314662920796 6.2867751790257458 0.42136079213367067 0.30905217041089911 0.24762811760198566 0.17620406479307604 7.4780011984163494E-2 1.158682134753164E-2 4.0721800375241209E-2 6.1261284270292649E-2 0.11268533707920447 0.223224820974254Standard measurent (psi)
Pressure difference (psi)
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