As per Central Public Health and Environmental Engineering Organization (CPHEEO), the minimum velocity at ultimate peak flow and maximum velocity of flow to be adopted in the design of gravity sewers shall be respectively :
CPHEEO Guidelines for Sewer Velocity
When designing gravity sewers, it's important to ensure the wastewater flows at appropriate speeds. If the velocity is too low, solid particles can settle down, leading to blockages (silting). If the velocity is too high, it can cause wear and tear on the sewer pipes (scouring).
The Central Public Health and Environmental Engineering Organization (CPHEEO) provides specific guidelines for the minimum and maximum flow velocities that should be adopted during the design of gravity sewers.
Minimum Velocity in Gravity Sewers
The minimum velocity is crucial to ensure that self-cleansing occurs, meaning the flow itself is sufficient to carry away settled solids. CPHEEO recommends that at the ultimate peak flow condition, the minimum velocity should be maintained to prevent silting.
According to CPHEEO guidelines, the minimum velocity at ultimate peak flow should be 0.8 m/s.
Maximum Velocity in Gravity Sewers
The maximum velocity is set to prevent excessive abrasion and scouring of the sewer pipe material, which can damage the pipe over time. High velocities also lead to increased friction and potential operational issues.
CPHEEO specifies a maximum permissible velocity for gravity sewers.
According to CPHEEO guidelines, the maximum velocity of flow should be 3 m/s.
Comparing with Options
We need to find the option that lists the minimum velocity as 0.8 m/s and the maximum velocity as 3 m/s, respectively, as recommended by CPHEEO.
- Option 1: 0.4 m/s and 2.0 m/s
- Option 2: 0.6 m/s and 3.5 m/s
- Option 3: 0.8 m/s and 3 m/s
- Option 4: 0.45 m/s and 1.5 m/s
Comparing the CPHEEO recommended values (0.8 m/s and 3 m/s) with the options, we find that Option 3 matches these values.
Summary of CPHEEO Sewer Velocity Standards
| Parameter | CPHEEO Recommendation |
|---|---|
| Minimum Velocity (at ultimate peak flow) | 0.8 m/s |
| Maximum Velocity | 3 m/s |
Therefore, based on CPHEEO standards, the minimum velocity at ultimate peak flow is 0.8 m/s and the maximum velocity of flow is 3 m/s for gravity sewer design.
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