Essay on Experiment 10

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Experiment 10 - Flow Characteristics of Valves

NAME: CHER SUNG KANG

GROUP NUMBER: B21

EXPERIMENT NUMBER: 10

DATE OF EXPERIMENT: 28/11/2011

DATE OF REPORT SUBMISSION: 5/11/2011

MARK/20 (for demonstrator use):

Introduction
Aim: 1. Describe operation of various types of valves
2. Measure frictional losses due to flows through different valves
3. Identify sources of errors

Background & theory: In this experiment, the relationship between volumetric flow rate and percentages of valve opening is determined by knowing that volumetric of flow rate of air through the flow meter is proportional to the square root of the differential head across the manometer. Graph of volumetric flow rate (%) vs valve opening (%) can
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The average value for ∆h is then determined by using the sum of the 3 sets of ∆h values dividing by 3. Therefore, for every half a turn, there would be an average value for ∆h.
Sample calculation for ∆h for gate valve at 0 turn at first set of values: 48 cm – 32.2 cm = 15.8 cm.
Average value of ∆h at 0 turn: (15.8 cm + 15.5 cm + 15.5 cm)/3 = 15.6 cm
√∆h = √15.6 = 3.95 (This value is taken as a constant because we are using the relationship of Q α √∆h where volumetric flow rate, Q is proportional to the √∆h, the square root of differential head across the manometer.
For gate valve: ∆h(average in cm) | Valve opening (%) | Volumetric Flow rate (%) | √∆h (constant) | 15.6 | 100.00 | 100.00 | 3.95 | 15.5 | 90.91 | 99.68 | 3.94 | 15.6 | 81.82 | 99.89 | 3.95 | 15.2 | 72.73 | 98.82 | 3.90 | 11.4 | 63.64 | 85.49 | 3.38 | 14.0 | 54.55 | 94.62 | 3.74 | 12.9 | 45.45 | 90.94 | 3.59 | 11.0 | 36.36 | 83.97 | 3.32 | 8.1 | 27.27 | 72.06 | 2.85 | 3.9 | 18.18 | 50.21 | 1.98 | 0.4 | 9.09 | 16.67 | 0.66 | 0.1 | 0.00 |
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