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
Advantage
· Power loss is less
· Head loss is negligible
Disadvantage
· 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 purpose • 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 |