1. The five critical pumping points in sanitation
Intake, transfer, boosting, lift stations and treatment have different requirements. Characterize the liquid and solids, suction pressure and operating duty at each point; the word “water” does not supply all the data selection needs.
The first is surface raw water intake, with sand and silt in suspension and a level that varies over the year; deep-well intake (tube well, designed under NBR 12212) uses a submersible or vertical-shaft pump. The second is treated water pumping from the treatment plant to the reservoirs, with potable water and residual disinfectant. The third is the in-line booster between pressure zones, which receives network pressure at suction and often runs with speed control.
The fourth is the sewage lift station, where the challenge is the solids, fibers and sand that pass the screen. The fifth is the internal process of water and wastewater treatment plants: filter backwash water, service water, sludge recirculation and treated effluent, each a different fluid. Viscous process fluids are assessed on the FBE external gear pump, whose manual (MTEC-01/01, p.1) also lists sanitation among its applications.
| Point | Fluid and solids | FBCN criterion | System design standard |
|---|---|---|---|
| Surface raw water intake | Water with sand and silt; variable level | NPSH at minimum level; S2/S3 sealing for particles | ABNT NBR 12213 (intake) and NBR 12214 (pumping station) |
| Treated water pumping | Potable water with residual disinfectant | Cast iron, WCB or CF8M casing per the utility specification | NBR 12214; potability: Annex XX of Consolidation Ordinance GM/MS No. 5/2017 |
| In-line booster between zones | Potable water with network pressure at suction | Suction up to 10 bar; discharge pressure per Figures 1 to 4 | NBR 12214; distribution network: NBR 12218 |
| Sewage lift station | Sewage with solids, fibers and sand | Suspended solids: consult FB; raw sewage: solids-handling pump (outside the FB line) | NBR 12208 (sewage lift station); collection network: NBR 9649 |
| Water and wastewater treatment processes | Backwash and service water, sludge, treated effluent | FBCN for clean or turbid liquids; sludge assessed case by case | NBR 12216 (water treatment) and NBR 12209 (wastewater treatment) |
2. Raw water vs treated water pumping — critical differences
Compare suspended solids, chemistry and operating levels. Sand and silt can wear components; pH, chlorides, dissolved metals and disinfectant residual enter compatibility assessment. Both intake and treated-water reservoir have minimum and maximum levels to check. Utility inspection history helps assess wear and maintenance; there is no single service life for each water type.
The FBCN manual (MTEC-03/00) gives the criteria for each case. Casing in cast iron, A216 WCB carbon steel or A743 CF8M stainless (Figures 1 and 2). Sealing by arrangement (item 10): ST, lubricated by the pumped fluid itself, for clean, non-aggressive fluids; S2, with external liquid, for solid particles or small fibers in suspension; S3, with external flushing, for abrasive particles or a tendency to crystallize; or a mechanical seal defined for the application.
And impeller material limits peripheral speed: up to 40 m/s in cast iron, 60 m/s in ductile iron or carbon steel and 80 m/s in stainless steel (item 6).
Engineering note
Calculation example with item 6 of the manual: a 250 mm impeller at 3,500 rpm has a peripheral speed of π × 0.25 × 3,500 / 60 ≈ 45.8 m/s — above the 40 m/s limit for cast iron; the impeller must be ductile iron, steel or stainless. The same impeller at 1,750 rpm runs at ≈ 22.9 m/s. High-head boosters at 3,500 rpm are exactly where this limit appears.
3. Sewage lift stations — the FBCN technical window
The FBCN is a normalized process centrifugal pump: manual MTEC-03/00 indicates it for clean or turbid liquids and asks for FB consultation for fluids with suspended solids (item 2.3). The impeller is radial, single-suction, with a wear ring (item 2.2) — it is not a free-passage or chopper impeller. That defines where it fits in sewerage.
Raw sewage with fibers, rags, plastics and sand calls for a solids-handling pump — submersible or dry-pit, with free-passage, vortex or chopper impeller —, outside the scope of the reviewed FB catalogues.
The FBCN fits the streams where the analysis confirms a liquid without coarse solids — treated effluent, reuse water, service water, clean drainage — and, in sewage after screening and grit removal, only after FB assesses the solids that pass the screen and the impeller passage; lift station design follows ABNT NBR 12208.
4. NPSH and changing levels at raw-water intakes
River or reservoir level changes static head and available NPSH. Recalculate the pump/system curve intersection at minimum and maximum levels, considering losses and temperature. Check flow, power and required NPSH on the model curves in each condition; do not assume identical behaviour for every impeller or control system. The published FBCN curves are valid for clean water at 20 °C, as each curve header states; other temperatures and solids content enter the selection review.
Criterion: calculate NPSH available at the minimum design level, with the maximum water temperature and suction losses with aged piping, and compare it with the NPSH required from the model curve at the highest expected flow. The margin between them is a system design criterion; FB provides the NPSH required of the selected model.
The FBCN is a horizontal surface pump: a well whose dynamic level is beyond suction reach calls for a submersible or vertical-shaft pump, outside the FB line. The 10 bar maximum suction pressure (Table 1) is the relevant limit at the other extreme, on in-line boosters.
Engineering note
Worked example with hypothetical data: intake at sea level (standard atmosphere, 101.325 kPa), water at 30 °C (vapour pressure 4.247 kPa and density 995.6 kg/m³, NIST), minimum level 3.0 m below the pump shaft and 1.0 m of suction losses. NPSH available = (101,325 Pa − 4,247 Pa) / (995.6 kg/m³ × 9.81 m/s²) − 3.0 m − 1.0 m ≈ 9.94 − 4.0 ≈ 5.9 m. At altitude, local barometric pressure is lower and the result drops; at maximum level, it rises. The value is compared with the NPSH required from the curve at the highest expected flow.
5. System design standards and supplier registration with utilities
ABNT sanitation standards cover system design, not the pump. In public water supply: conception studies (NBR 12211), tube well for groundwater (NBR 12212), surface water intake (NBR 12213), water pumping or lift station (NBR 12214), water treatment plant (NBR 12216), distribution reservoir (NBR 12217) and distribution network (NBR 12218). In sanitary sewerage: conception study (NBR 9648), collection networks (NBR 9649), sewage pumping or lift station (NBR 12208) and sewage treatment plant (NBR 12209).
The designer applies these standards to define flows, heads, number of sets and standby; the pump is selected for the resulting point. The potability standard for water for human consumption is Annex XX of Consolidation Ordinance GM/MS No. 5/2017, as updated by Ordinances GM/MS No. 888/2021 and No. 2,472/2021. None of these standards certifies the pump, and FB does not declare product compliance with them.
Supplier registration: each utility keeps its own registration and qualification process, with technical, legal and tax requirements defined in the tender. FB does not publish a list of utility registrations; the documentation required in each process — attestations, catalogs, data sheet, model curve and, when contracted, test and material certificates — is defined in the proposal.
6. What the FBCN offers sanitation — and what to check
The FBCN is a horizontal normalized centrifugal pump with back pull-out construction: the bearing assembly comes out without disconnecting the piping (MTEC-03/00). The manual states mechanical construction per ASME B73.1; dimensions are those of the manual tables. Interchangeability with a pump from another manufacturer is not assumed: replacement is checked model by model against the dimensional drawing (baseplate, nozzles, flanges and shaft).
In operation this means maintenance of impeller, sealing and bearings without touching the piping, and parts identified by the manual list, numbered per DIN EN 24250 (Table 5). The bearing housing has two oil-lubricated rolling bearings, with dipstick or optional automatic oiler (Table 1). Intervention times and bearing life depend on installation and operation; FB does not publish these values.
- Flow up to 2,200 m³/h and head up to 135 m as series maximums, not simultaneous: 43 models up to DN 150 with dimensions in the manual and 11 on request: the 100-500 and the 10 large-capacity models (150-500 to 300-340)
- Casing in cast iron, A216 WCB carbon steel or A743 CF8M stainless; ANSI B16.1 flanges on cast iron and B16.5/B16.42 on steel and ductile iron — if the network uses another flange standard, state it in the enquiry
- Packing seal in arrangements ST, S1, S2 or S3, or mechanical seal according to the application (item 10)
- Limits to check: suction pressure up to 10 bar, minimum flow of 0.1 to 0.15 × best-efficiency flow, pressure × temperature per Figures 1 to 4 and peripheral speed per impeller material
- Documentation and tests: the manual states mechanical construction per ASME B73.1 and hydrostatic test per ANSI B73.1; at the Cabreúva-SP factory, hydraulic bench tests follow ANSI/HI 14.6; data sheet, curve, tests and certificates for each supply are defined in the proposal