flow measurement (variable head meter)
Post on 09-Feb-2016
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Flow MeasurementFlow Measurement(variable head meter)(variable head meter)
bybyAshfaq Md. AnseryAshfaq Md. Ansery
Venturimeter
Venturimeter
Theory (Venturimeter)
Discharge Coefficient Cd
Dimensional analysis of venturi tube indicates C = f (Re, D1, D2)
Discharge Coefficient
Venturimeter cont…. The value of C
C = 0.99 for large tube C= 0.97-0.98 for small tube
Provided the value is such as to give reasonably high Reynolds number
A roughing of the surface of the converging section from age or scale deposit will reduce the coefficient slightly (1-2%)
Venturimeter cont…Limitations High installation cost It occupies considerable
space
Limitations (cont…) Ratio of throat to pipe diameter
(D2/D1) cannot be changed- the maximum measurable flow rate is fixed
So if the flow range is changed, the throat diameter may be too large to give an accurate reading or to small to accommodate the next maximum flow rate
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