ABE TUTORIALS

PROBLEM 25: TRIANGULAR WEIR FLOW CALCULATION

A PUMP WAS TESTED TO MEASURE THE FLOW RATE USING A 90 DEGREE TRIANGULAR WEIR. TESTS HAVE SHOWN THAT THE HEAD OF WATER INTO THE WEIR AVERAGES TO 13 CM. WHAT IS THE AVERAGE RATE OF FLOW OF THE PUMP?

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a. 8.4 lps

b. 22.2 lps

c. 32.2 lps

d. none

Correct Answer: A (8.4 lps)

Step 1: Identify the Formula

For a 90° triangular weir, the discharge (Q) is typically calculated using the formula:
Q = 0.0138 × H^(5/2)
Where Q is in L/s and H is in cm.

Step 2: Substitute the Given Values

H = 13 cm
Q = 0.0138 × (13)^2.5

Step 3: Final Computation

Q = 0.0138 × 609.337
Q = 8.408 L/s ≈ 8.4 lps

Result: a. 8.4 lps