Home
Back
Detention Time Formula:
| From: | To: |
Detention time (also called retention time) is the theoretical time required for a given amount of water to pass through a tank at a given flow rate. In sedimentation tank design, it represents the average time that water remains in the tank.
The calculator uses the detention time formula:
Where:
Explanation: This formula calculates how long water remains in the sedimentation tank, which is critical for effective particle settlement.
Details: Proper detention time is essential for effective sedimentation. Too short detention time may not allow sufficient settling, while too long detention time may lead to septic conditions and inefficient use of space.
Tips: Enter the tank volume in cubic meters and flow rate in cubic meters per hour. Both values must be positive numbers.
Q1: What is the typical detention time for sedimentation tanks?
A: For rectangular sedimentation tanks, detention time typically ranges from 2-4 hours for primary treatment and 4-8 hours for secondary treatment.
Q2: How does detention time affect sedimentation efficiency?
A: Longer detention times generally allow more complete settling of particles, but beyond optimal ranges, efficiency gains diminish while costs increase.
Q3: Can I use different units with this calculator?
A: The calculator is designed for metric units. Convert other units to m³ for volume and m³/hr for flow rate before calculation.
Q4: What factors influence optimal detention time?
A: Particle size, water temperature, tank design, and the specific treatment objectives all influence the optimal detention time.
Q5: How is detention time related to overflow rate?
A: Detention time and overflow rate are inversely related. As detention time increases, overflow rate decreases, generally improving sedimentation efficiency.