Sensing for liquid level of a column.pptx

How to use a sensor

1. Pressure Sensing using a liquid filled column

2. Background- Pressure Measurement Evangelista Torocelli     Mercury Barometer Used in measuring Atmospheric Pressure Used mercury as the measuring liquid Height of the mercury from the base is directly proportional to the atmospheric pressure

3. Eugene Bourdon – bOURDON tUBE Bourdon Tube straightens due to the filled water pressure Turns the mechanism and thus the pointer Pressure Gauge has the same mechanism

4. U – Tube Manometer Aims Compare U-tube manometer and pressure gauge readings Compare the vertical and inclined  manometer readings Compare pressure transducer experimental and theoretical results to variations in pressure Difference in pressure on both ends make the uneven levels  Liquid on the lower side means high pressure than the other side Pressure = vertical distance between both sides of liquid

5. Experimental apparatus Perspex cylinder & U-Tube Manometer Pressure gauge Discharge valve

6. Experimental procedure Before starting experiment Empty and check Fill the tank  Specific gravity; and temperature Atmospheric pressure, height and angle of inclination

7. Part A - Calibration Manometer inlet & reference gauge Mark height and fill water Record manometer and gauge Repeat (fill water) Discharge valve to reduce the water Record manometer and gauge Part B – Pressure Measurement Random heights Record manometer and gauge Do for incline and vertical U-tube manometer Pressure Transducer Take zero bar reading  Then 0.336 bar; and 0.164 bar Then add 0.5 increments until 2.5

8. Pressure transducers Digital pressure sensor Takes pressure inputs Converts to analogue electrical signal In volts

9. Results and discussion: Part A Data recorded from experiment: Atmospheric pressure: 100.071kpa Temperature: 22 ℃ Specific gravity of water: 1g/cm 3 Theoretical specific gravity: 1g/cm 3 Hydrometer has a 0% experimental error Filling   Height (cm) Δ h (m) Pressure (Pa) Gauge (Pa) 15.5 0.091 892.71 29.8 0.141 1383.21 1800 45 0.19 1863.9 3500 59.8 0.232 2275.92 5000 75 0.278 2727.18 6900 Discharging Height (cm) Δ h (m) Pressure (Pa) Gauge (Pa) 75 0.278 2727.18 6900 59.8 0.235 2305.35 5000 44.9 0.191 1873.71 3200 30 0.145 1422.45 2000 15 0.093 912.33 Analysis of the graph: There is a linear relationship The manometer produces consistent results Curve equation is the same as P= ρgh Table 1: Raw data from Part A Graph 1: Pressure vs height difference graph

10. Based on the line of best fit, we can see which sensor is more accurate The hysteresis is 25.69Pa σ filling = 645 and discharging =638 The are some inaccuracies which could be due to rounding errors The hysteresis is 3.475 There are larger differences between some points, but the hysteresis is lower due to the zero reading σ filling =2405 & discharging=3281 Graph 2: Tube height vs manometer pressure Graph 3: Tube height vs pressure gauge pressure

11. Results and discussion: Part B Δ h randoms (m) Pressure open tube (Pa) Pressure closed tube (Pa) 0.266 2441.88 93689.58 0.216 1982.88 95327.85 0.169 1551.42 97917.69 Results from random points: The randoms were interpolated using the graph from part A. The pressure of the closed tube has 3 assumptions: Pressure at discharge point is atmospheric pressure. H=0 at the discharge point. The fluid has velocity=0 at the selected random heights. Height (cm) Δ h (m) pressure (pa) Gauge (Pa) 38.4 0.161 1562.46 2400 49.8 0.196 1902.13 3800 66.3 0.245 2377.66 5200 Results from inclined manometer: Equation use: p= ρ gh *sin(x) The angle of inclination is 81.6 At lower pressures, the manometer pressure has lower differences Table 2: Randoms pressure readings Table 3: Inclined manometer readings

12. Which pressure sensor is more accurate ? Manometer: Has a higher accuracy than a pressure gauge at lower pressures Less sources of error Relies only on gravity and density Need to be kept upright Sensitive Pressure Gauge: Higher accuracy at high pressures Does not register a pressure reading at pressures lower than 1kpa. Prone to human error It is a mechanical device. Relies on calibration, friction, wear of moving parts and elasticity. Also affected by corrosion.

13. Data from Pressure transducer: At zero reading the maximum voltage measured should be 5mV. This means that there is a 60% experimental error. The meter is probably was not calibrated correctly. Could also happen due to overuse. Pressure Exp Voltage Theo. Voltage 0.008 0.334 1.32 1.336 0.5 1.987 2 1 3.947 4 1.5 5.979 6 2 7.975 8 2.5 9.982 10 A linear relationship is evident The gradient is Vmax/Pmax The experimental error is 0.18% High accuracy Table 4: Raw data from pressure transducer Graph 3: Pressure vs voltage graph

14. Conclusion  The primary goal was to calibrate a U-tube manometer in the lab, evaluating its practicality, accuracy, and precision compared to a standard pressure gauge. The density of the water was measured using a hydrometer. When compared to the literature value, a 0.2% error was found.  Directly proportional relation the disparity in height between the manometer and the pressure calculated. When heights were measured randomly, the consistent direct correlation was still evident, confirming the experiment's replicability.

15. Conc. Additional examination of the graph indicated that the readings from the U-tube manometer can be correlated with those acquired using a pressure gauge, making it a viable tool for obtaining pressure measurements Using a data logger to record the pressure can be useful in the future research.

16. RECOMMENDATIONS To minimize human error, the readings should be taken by one person Replace a traditional pressure gauge with an electronic pressure gauge  using a denser fluid within the manometer The temperature of the water must be kept at room temperature Conduct additional trials to ensure reliable outcomes.

17. Bibliography Anon., 2022. electrical volt. [Online] Available at: https://www.electricalvolt.com/2022/08/u-tube-manometer-principle/ Anon., n.d. Bourdon Instruments. [Online] Available at: https://www.bourdon-instruments.com/fr/en/company/history-and-innovation/a/history-and-innovation G.U.N.T, 2019. Learn2023. [Online] Available at: https://learn2023.ukzn.ac.za/pluginfile.php/527576/mod_resource/content/1/Instruction%20Manual%20for%20Pressure%20Sensors.pdf Kaku, M., 2023. Britannica. [Online] Available at: https://www.britannica.com/biography/Evangelista-Torricelli Mahommedi , A., 2023. learn2023. [Online] Available at: learn2023.ukzn.ac.za Missouri University of science, n.d. Missouri University of science. [Online] Available at: https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fweb.mst.edu%2F~cottrell%2FME240%2FResources%2FCalibration%2FExplanation%2520of%2520Hysteresis%2520calculation.doc&wdOrigin=BROWSELINK Variohm , n.d. Variohm . [Online] Available at: https://www.variohm.com/news-media/technical-blog-archive/what-is-a-pressure-sensor-#:~:text=A%20pressure%20sensor%20is%20a,information%20into%20an%20output%20signal