What it is and how to size a Booster Pump

A bomba de recalque is the pump that lifts water from a lower reservoir to an upper reservoir or a higher point of use, through the discharge (recalque) line that starts at the pump outlet. In a building, it moves water from the cistern to the rooftop tank. To do so, it overcomes the height difference between the water surfaces and the piping losses; in industry, the same duty appears in water transfer between tanks.

Start from two numbers. Flow is the volume to transfer divided by the pumping time set by the design. Per the Hydraulic Institute, total head adds the static head (the height difference between the free surfaces of the cistern and the tank, plus the pressure difference between them) and the friction losses in the piping and components, which grow with flow. With the (Q, H) point, check the model curve for power and for the NPSH required against the NPSH available; the design defines controls and redundancy.

Suction is the section from the source reservoir to the pump inlet; discharge (recalque) is the section from the pump outlet to the destination. Splitting at the pump shaft the height difference between the levels, which, with open reservoirs, is the Hydraulic Institute's static head, gives the static suction height (from the water level to the shaft) and the static discharge height (from the shaft to the discharge point); the losses of each section add to them in the total head. With the shaft below the water level, suction is positive; above it, suction is negative, as São Paulo's IT 22 classifies fire pumps (C.1.12), and the NPSH available decreases.

A booster pump is installed in series in a line to raise the pressure of the water that already reaches it, not to fill a reservoir; per the Hydraulic Institute, pumps in series add head at the same flow. Its purpose is to pressurize a building supply network or an industrial line, and it is controlled by network pressure, not by level; the Hydraulic Institute gives the example of a booster fitted with a variable frequency drive for fluctuating flow. The transfer (recalque) pump, controlled by level, fills the rooftop tank. The same centrifugal family can serve both duties, with a duty point and controls specified for each. Because a booster receives water under pressure, check the suction limit: 10 bar on the FBCN Series (manual MTEC-03/00, Table 1).

The need for standby capacity depends on required supply continuity and design requirements. Where duty and standby pumps are provided, sizing, alternation, controls and maintenance must be coordinated. Confirm the configuration with the responsible professional before purchasing the package.

Very frequent starts require installation assessment. Check reservoir levels, sensors, controls, valves, demand and pump suitability for the duty. In a pressurized network, include pressure-control devices. The symptom alone does not identify the cause; record conditions and consult maintenance.

Yes. The FBCN Series was designed for clean or turbid liquids in applications such as the chemical, petrochemical, paper, pulp, steel, mining, food, textile, pharmaceutical and sanitation industries (manual MTEC-03/00, p. 1). The series limits, 2,200 m³/h and 135 m, do not apply at the same time; size, materials and sealing (packing or mechanical seal) are defined in the inquiry. For viscous liquids, the choice moves to the FBE and FBEI gear pump series; for thermal oil, to the FBOT.

The transfer (recalque) pump fills the rooftop tank and is controlled by level. The booster (pressure set) raises the pressure in the supply network and is controlled by pressure or by a variable frequency drive. The jockey pump maintains fire-network pressure between preset limits while no water is flowing and is sized to replenish allowable leakage and normal pressure drops (NFPA 20). Function, controls and network are not interchangeable: select by service, not by pump name.