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Pump is used when one needs to transport the water from lower ground level to higher ground level. It can also be used when the level of the OSD is lower than the drain/river level that it has to discharge into.

The design of the pump is according to chapter 19 of MSMA 2nd edition. It essentially consists of a few parts: inflow hydrograph, storage estimation, pumping rate estimation and level pool routing.

For OSD with pump, the above pump design still applies, and in addition to that, the PSD and SSR is also checked in accordance with MSMA 2.

We provide you a project file benchmarked with the calculation in this spreadsheet

1. Develop an inflow hydrograph

The inflow hydrograph is developed based on the rainfall data, which users can plug in all of the information in MITS. The inflow hydrograph is then developed based on the data and also is benchmarked as in Table 19.B1. The development of hydrograph also can be referred to as per Chapter 2.

2. Estimate Storage Volume and Stage-Storage Relationship

Trial and error is necessary for the storage volume estimation and stage-storage relationship can be developed which can be referred to in Table 19.B2.

Stage-Storage relations is plotted:

3. Estimate Pumping Rate and Number of Pumps

Given the storage volume, the estimated pumping rate and the number of pumps can be determined.

4. Estimate the Total Dynamic Head

Total Dynamic Head is the total equivalent height of fluid to be pumped. The calculation is the sum of the static head, velocity head and head losses in the pump discharge system due to friction. The equation can be referred to in MSMA 2nd Edition, Equation 19.1.

TDH = Hs + hf + hv + hl

###### Hs = Static head (m)hf = Friction head (m)hv = Velocity head (m)hl = Losses through fittings, Valves, etc. (m)

Users can insert the value of the lowest level of storage, highest level of storage and the higher level that need to be pumped.

Based on the above elevation values, the TDH is calculated in accordance with the Equation 19.1. The calculation of the TDH and head losses are provided as reference.

5. Selection of Pump Performance Curve

Each pump has their own performance curve which has been developed by the manufacturer and to establish a reasonable balance between total dynamic head, discharge, efficiency, and energy requirements. Examples of curve sheet provided by manufacturer can be referred in MSMA 2nd Edition Figure 19.B5.

6. Pump Cycling

With the number of pumps set, the start and stop elevation are assigned as in Table 19.B3. Start level is the when the tank level reaches this value, the pump will start and stop level is when the tank level reaches this value, the pump will be stopped.

Stage-Discharge of rising and dropping water level is calculated based on the Pump Performance Curve given elevation and TDH, which is provided by the manufacturer. The relationship can be referred to Table 19.B4 (rising water level) and Table 19.B5 (dropping water level). Figure 19.B6 is the relationship shown in graph.