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Roof Drain Pipe Sizing Formula:
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Roof drain pipe sizing is the process of determining the appropriate diameter of drainage pipes based on the expected flow rate and desired flow velocity. Proper sizing ensures efficient water removal from roofs while preventing overflow and structural damage.
The calculator uses the pipe sizing formula:
Where:
Explanation: The formula calculates the required pipe diameter based on the flow rate and desired velocity, ensuring optimal drainage performance.
Details: Correct pipe sizing is crucial for preventing water accumulation on roofs, reducing the risk of leaks, structural damage, and ensuring efficient water management during heavy rainfall.
Tips: Enter the flow rate in cubic meters per second (m³/s) and the desired flow velocity in meters per second (m/s). Both values must be positive numbers.
Q1: What is a typical flow velocity for roof drains?
A: Typical flow velocities range from 0.6 to 3 m/s, with 1-2 m/s being most common for efficient drainage without excessive pressure loss.
Q2: How do I determine the flow rate for my roof?
A: Flow rate depends on roof area and rainfall intensity. It can be calculated using: Q = (C × I × A) / 3600, where C is runoff coefficient, I is rainfall intensity (mm/h), and A is roof area (m²).
Q3: Are there standard pipe sizes for roof drains?
A: Yes, common standard sizes include 75mm, 100mm, 150mm, and 200mm diameters, but the required size depends on specific project requirements.
Q4: What factors affect pipe sizing besides flow rate?
A: Pipe material, slope, number of bends, and local building codes all influence the final pipe size selection.
Q5: Should I include a safety factor in my calculations?
A: Yes, it's recommended to include a safety factor of 1.2-1.5 to account for unexpected heavy rainfall or partial blockages.