CE 260 FLUID MECHANICS January Interim 2017 Experiment 1 Calibration of a Bourdon Pressure Gauge Your name: January/5/2017 Fluid Mechanics Laboratory Bradley University, Peoria, IL 61625 Objective The objective of this experiment is to calibrate a Bourdon pressure gauge. Materials and Methods The Bourdon pressure gauge is used in this experiment. The mechanism consists of tube with a thin wall (oval cross-section) bent to a circular arc encompassing about 270 degrees. It is rigidly held at one end where the pressure is admitted to the tube and is free to move at the other end. When the pressure is admitted, the tube tends to straighten. The movement at free end operates a mechanical system, whish moves a pointer around the graduated scale. The movement of the pointer is proportional to the pressure applied. The sensitivity of the gauge depends on the material used for construction of the apparatus and dimensions of the Bourdon tube. A series of weights is used with the apparatus, including a stainless steel piston with a mass of the stainless steel platform and the area across which the pressure is transmitted is recorded. Weights are added in increments specified by the instructor but to exceed 6.2 kg. After a weight has been added the piston is rotated gently to ensure that pressure transmission is smooth and even. The pressure scale is read at each weight increment when the weights are added. Once all the weights have been added and the maximum pressure is recorded, the weights are taken off in the same order that they were placed on the piston. After removing each weight, the pressure is recorded. After all the weights are removed (except the stainless steel platform) the entire procedure is repeated once more. Results and Discussion Table 1. Pressure Measurements – Trial 1 Mass added 0 1 2 2.5 3 3.5 4 4.5 Total mass on piston kg 1 2 3 3.5 4 4.5 5 5.5 Actual pressure kpa 30.91 61.8 92.7 108.17 123.6 139.08 154.5 169.99 Increasing pressure Gage Error (kPa) (kPa) 35 65 95 110 127 145 160 175 -4.09 -3.18 -2.27 -1.8 -3.36 -5.91 -5.46 -5.007 Decreasing pressure Gauge (kPa) Error (kPa) 35 65 95 113 130 145 155 165 -4.09 -3.2 -2.3 -4.83 -6.4 -5.92 -0.5 4.99 Bourdon Pressure Gauge (Increasing Pressure) Measured Pressure (Incr) in kPa 200 180 160 140 120 100 80 60 y = 1.0155x + 2.2012 R² = 0.9993 40 20 0 0 50 100 150 Actual (Theorteical) Pressure in kPa 200 Measured Pressure (Incr) in kPa Bourdon Pressure Gauge (Decreasing Pressure) 180 160 140 120 100 y = 0.9647x + 6.6641 R² = 0.9948 80 60 40 20 0 0 50 100 150 Actual (Theorteical) Pressure in kPa 200 Figure 1. Actual pressure versus measured pressure for “increasing” and “decreasing” cycles. Bourdon Pressure Gauge (Error Distribution for trial 1) Error (lncr) in kPa 6 4 2 0 -2 -4 -6 -8 0 50 100 Actual pressure in kPa 150 200 Figure 2. Error distribution for Trial 1. Table 2. Pressure Gauge Measurements – Trail 2 Mass added 0 1 2 2.5 3 3.5 4 4.5 Total mass on piston kg 1 2 3 3.5 4 4.5 5 5.5 Actual pressure Increasing pressure Gauge Error Decreasing pressure Gauge Error kPa 30.91 61.8 92.7 108.17 123.6 139.08 154.5 169.99 (kPa) 35 65 95 110 128 145 159 170 (kPa) 35 65 90 113 135 140 160 168 (kPa) -4.09 -3.2 -2.3 -1.83 -4.4 -5.92 -4.5 -0.01 (kPa) -4.09 -3.2 2.7 -4.83 -11.4 -0.92 -5.5 1.99 Measured Pressure (Incr) in kPa Bourdon Pressure Gauge (Increasing Pressure) 200 180 160 140 120 100 80 60 40 20 0 y = 0.9942x + 3.9243 R² = 0.9985 0 50 100 150 Actual (Theorteical) Pressure in kPa 200 Bourdon Pressure Gauge (Decreasing Pressure) Measured Pressure (Incr) in kPa 200 180 160 y = 0.9913x + 4.1161 R² = 0.9908 140 120 100 80 60 40 20 0 0 50 100 150 Actual (Theorteical) Pressure in kPa 200 Figure 3. Actual pressure versus measured pressure for “increasing” and “decreasing” cycles. Error (lncr) in kPa Bourdon pressure gauge (Error Distribution for trial 2) 4 2 0 -2 -4 -6 -8 -10 -12 -14 0 50 100 Actual pressure in kPa 150 Figure 4. Error distribution for Trial 1. Conclusion 200