Question

Which instrument does not measure cumulative flow?

• A. Propeller meter
• B. Deathridge meter
• C. Water meter
• D. Venturimeter

Hint:

Ask which of these four gives you a running total in litres or cubic metres, and which one only tells you the flow rate at that moment.

Answer 1

The Correct Option is D

Step 1: Cumulative or totalizing flow measurement means the instrument keeps adding up the volume of water that has passed, giving a running total over time, not just the instantaneous rate.

Step 2: A propeller meter has a rotating element whose number of turns is directly proportional to the volume passed, so its readout accumulates total volume, it measures cumulative flow.

Step 3: A Deathridge meter is a small propeller type meter commonly used at the outlet of irrigation channels specifically to record total volume delivered, so it also gives cumulative flow.

Step 4: A household or field water meter works exactly like its name suggests, it totals up the litres or cubic metres of water that flow through it, which is cumulative flow by design.

Step 5: A venturimeter works differently. It reads the pressure difference between the inlet and the constricted throat at that instant, and this difference is converted into an instantaneous rate of flow (say litres per second). Unless a separate integrating device is added on top, a plain venturimeter shows only how fast water is flowing right now, not how much has flowed in total.

Step 6: So among the four, the venturimeter is the one that does not measure cumulative flow, option 4.