Venturi Meter - Pharmaceutical Engineering B. Pharm Third Semester PDF Notes

Venturi meter

• When fluid is allowed to pass through narrow venturi throat then velocity of fluid increases and pressure decreases

• Difference in upstream and downstream pressure head can be measured by using Manometer

U v =    C v√ 2g . ∆H

Why Venturi meter if Orifice meter is available?

• Main disadvantage of orifice meter is power loss due to sudden contraction with consequent eddies on other side of orifice plate

• We can minimize power loss by gradual contraction of pipe

• Ventury meter consist of two tapperd (conical section) inserted in pipeline

• Friction losses and eddies can be minimized by this arrangement


·         Power loss is less

·         Head loss is negligible


·         Expensive

·         Not flexible it is permanent

·         Need technical export

·         Differences between orifice and venture meter

Orifice Meter

venture meter

• Cheap

• Easy to install

• Construction can be made

• Head losses are more

• Power losses are more, particularly coefficient of discharge is high

• Normally used for testing


• Greater flexibility

• Reading is larger under identical condition

• Expensive

• Fabrication is highly technical

• It should be purchased

from a dealer

• Head losses are insignificant

• Power losses are less

• Used in online installation

• Not flexible ,permanent

• The reading is comparatively smaller under identical conditions

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