Coefficient of discharge (Cd) in the orifice meter usually ranges betw...
Coefficient of discharge is the ratio of actual discharge to the theoretical discharge.

Coefficient of discharge for various devices are:
⇒
Venturimeter – 0.95 to 0.98⇒
Orifice meter – 0.62 to 0.65⇒ Nozzle – 0.93 to 0.98
∴ The coefficient of discharge for the nozzle meter lies between the venturi meter and the orifice meter.
Coefficient of discharge (Cd) in the orifice meter usually ranges betw...
The coefficient of discharge (Cd) is a dimensionless factor that represents the efficiency of an orifice meter in measuring the flow rate of a fluid. It is defined as the ratio of the actual flow rate to the theoretical flow rate. The Cd value depends on various factors such as the shape and size of the orifice, the fluid properties, and the flow conditions.
The correct answer to the given question is option 'C', which states that the coefficient of discharge (Cd) in the orifice meter usually ranges between 0.61 and 0.65. This range is commonly accepted for orifice meters and is based on experimental data and industry standards. Let's discuss this in more detail:
1. Definition and Significance of Cd:
- The coefficient of discharge (Cd) is a dimensionless factor that relates the actual flow rate through an orifice to the theoretical flow rate.
- It takes into account the effect of various factors on the flow measurement accuracy, such as friction, turbulence, and contraction.
2. Factors Affecting Cd:
- Size and shape of the orifice: The Cd value depends on the shape and size of the orifice. Different shapes and sizes result in different flow patterns and affect the discharge coefficient.
- Fluid properties: The properties of the fluid, such as density and viscosity, affect the Cd value. Different fluids have different Cd values for the same orifice.
- Flow conditions: The flow conditions, such as Reynolds number and flow regime (turbulent or laminar), also influence the Cd value.
3. Experimental Data and Industry Standards:
- The range of Cd values mentioned in option 'C' (0.61-0.65) is commonly accepted in practice.
- These values are based on extensive experimental data and have been adopted in industry standards such as ISO 5167.
- The Cd values within this range provide a reasonable level of accuracy for flow measurements using orifice meters.
4. Variation in Cd Values:
- It is important to note that the Cd values can vary for different orifice designs, fluid properties, and flow conditions.
- The given range (0.61-0.65) is an average range and may not be applicable in all cases.
- Manufacturers and researchers may provide specific Cd values for their orifice designs based on calibration and testing.
In conclusion, the coefficient of discharge (Cd) in the orifice meter usually ranges between 0.61 and 0.65, as stated in option 'C'. This range is commonly accepted based on experimental data and industry standards. However, it is important to consider specific factors such as orifice design, fluid properties, and flow conditions, which may cause variations in Cd values.