Venturimeter – Primary Use in Internal Flow Measurement A Venturimeter installed in a pipe is used to determine the volumetric discharge of the liquid flowing through that pipe using pressure differences and Bernoulli’s principle.

Introduction:
A Venturimeter is a differential-pressure flowmeter. By constricting the cross section, it relates measured pressure drop to flow rate using energy and continuity principles.

Given Data / Assumptions:

• Incompressible, steady flow in a full pipe.
• Known meter geometry (inlet, throat, diffuser).
• Empirical discharge coefficient accounts for losses.

Concept / Approach:

Bernoulli between inlet and throat gives a relation between pressure drop and velocity increase. With continuity, one can express Q in terms of measured differential pressure and meter constants. Hence, the Venturimeter measures discharge; velocity can be inferred only after dividing by area.

Step-by-Step Solution:

Verification / Alternative check:

Calibration against gravimetric or volumetric standards confirms accuracy within stated uncertainty when the meter is properly installed.

Why Other Options Are Wrong:

Velocity alone is not the direct instrument output; pressure is not the primary measured quantity (that is a means to infer Q). Pressure difference is measured but the device is classified by its purpose: discharge measurement. Density is not directly measured.

Common Pitfalls:

Ignoring installation requirements (straight runs, Reynolds-number effects) and calibration coefficients, which can bias Q.

Final Answer:

measure the discharge of liquid flowing in a pipe