KEVOS® MAKEOS · Hydraulics
Sump or Pit Pump-Out Plan (Simpson Section Area, Volume, Time)
How much water is in this pit or sump of irregular cross-section, and how long will my pump take to empty it with water still running in?
Pump-out plan for a pit, trench or sump of uniform length with an irregular cross-section: the section area by Simpson’s rule from depths measured at equal spacings across it (as the Simpson’s rule area tool), the volume over the length, the net pumping rate after inflow, and the time to empty, against the time you have.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Spacing between depth readings | mm | Equal spacing between the depth readings across the pit. |
| Number of spaces (even) | Number of spaces between readings (must be even). | |
| Depths at each reading, d₀ … d₁₀ (only d₀ to d_N are used) | ||
| d0 | mm | Water depth at the first reading. |
| d1 | mm | Depth at reading 1. |
| d2 | mm | Depth at reading 2. |
| d3 | mm | Depth at reading 3. |
| d4 | mm | Depth at reading 4. |
| d5 | mm | Depth at reading 5. |
| d6 | mm | Depth at reading 6. |
| d7 | mm | Depth at reading 7. |
| d8 | mm | Depth at reading 8. |
| d9 | mm | Depth at reading 9. |
| d10 | mm | Depth at reading 10. |
| Pumping | ||
| Length of the pit | mm | Length of the pit along which the section is uniform. |
| Pump flow | L/min | Flow the pump delivers at the pumping head. |
| Inflow while pumping | L/min | Water still entering while pumping. |
| Time available | min | Time you have to empty it. |
Method and formulas
- Area = (spacing ÷ 3)(d₀ + 4d₁ + 2d₂ + … + 4d_(N−1) + d_N) (as the Simpson’s rule area tool).
- Volume = section area × length.
- Time = volume ÷ (pump flow − inflow).
- Example: the section is 4.2333 m², holding 25,400 L; at a net 500 L/min it takes 50.8 min.
Limitations
- Uniform section along the length; irregular pits need several sections averaged.
- Pump flow taken as constant although head rises as the level falls.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan dewatering of a machine pit or trench
- Estimate a sump volume from soundings
- Size a pump for a pump-out time
Who it is for
- Maintenance supervisors
- Plant engineers
- Site engineers
What you get
- Section area by Simpson’s rule
- Volume of water
- Net pumping rate and time to empty
Interpreting the result
- Inflow eats directly into pumping: a pump only slightly larger than the inflow never empties the pit.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 67–68. Topic reference; no source tables or recommended settings are reproduced.
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Open the Sump or Pit Pump-Out Plan (Simpson Section Area, Volume, Time) calculator
