Industrial Pump Dictionary

There are two NPSH values: NPSH available (NPSHa), calculated by the installation designer from suction height, friction losses and fluid vapor pressure; and NPSH required (NPSHr), provided by the pump manufacturer on the characteristic curve. The rule of thumb is NPSHa > NPSHr + safety margin (typically 0.5 to 1.5 m), otherwise cavitation occurs and damages the impeller. Hot, volatile or near-vaporization fluids require special attention in sizing.

Classic cavitation symptoms are characteristic noise ("gravel inside the pump"), excessive vibration, flow and efficiency drop, and premature erosive wear on the impeller suction side. Prevention is achieved by correct NPSHa sizing, keeping the pump near the suction level, avoiding restrictions on the suction line, and selecting resistant materials for critical applications. External gear pumps (FBE) are less sensitive to cavitation than standardized centrifugals (FBCN) due to the positive displacement principle.

In centrifugal pumps (like the FBCN), flow depends directly on the installation head — the higher the head, the lower the flow. In positive displacement pumps (like FBE and FBEI), flow is nearly constant and proportional to speed, regardless of discharge pressure, making them ideal for precise dosing. The FBCN covers flow up to 2,200 m³/h; the FBE, from 0.5 to 6,500 L/min; and FB Bombas fire systems go up to 10,000 L/min.

Total head is the sum of: geometric head (level difference between suction and discharge), piping friction losses (friction in pipes, valves and fittings) and required residual pressure at delivery point. Unlike gauge pressure in bar or kgf/cm², head in meters is independent of fluid density — conversion is direct: H(m) = P(bar) × 10.2 / specific gravity. The FBCN line delivers up to 135 m of head, with Q×H curves available for each of the 53 models (43 standard + 10 large capacity); for greater heights, series or multistage pumps are used. Correct selection requires the pump curve to intersect the system curve at the desired operating point, preferably near BEP.

Operating far from the BEP (for example, with the discharge valve partially closed) causes internal recirculation, vibration, accelerated bearing and seal wear, and unnecessary energy consumption. Best practice is to select a pump whose BEP falls between 80% and 110% of the expected operating flow. FBCN technical manuals include characteristic curves with the BEP clearly marked for each of the 53 models in the series (43 standard + 10 large capacity).

The curve is the central technical document for pump selection: the operating point is determined by the intersection of the pump curve and the installation friction curve. For correct selection, the designer must overlay both curves and verify that the crossing point is near the BEP of the chosen pump. FBE (12 sizes) and FBCN (53 models) technical manuals include curves for 1750 and 3500 rpm at 60 Hz.

The maximum allowable pressure depends on casing material and fluid temperature — the FBCN manual includes charts (Figures 1-4) showing how maximum pressure drops with temperature for cast iron, A216 WCB carbon steel and A743 CF8M stainless steel. For cast iron, the typical limit is 20 bar at -50 to 120°C, dropping to 10 bar at 260°C. Operating above these limits compromises the pump's mechanical integrity.

Reference values: water (1 cSt ≈ 31 SSU), diesel oil (3 cSt ≈ 37 SSU), SAE 30 oil at 40°C (150 cSt ≈ 700 SSU), honey (10,000 cSt ≈ 46,500 SSU), hot asphalt (50,000 cSt ≈ 230,000 SSU). The FBE line supports up to 100,000 SSU — above this, FB Bombas engineering recommends the FBEI with specific configuration. Standardized centrifugals (FBCN) lose efficiency dramatically above 500 SSU.

The discharge head (Hr) is the geometric difference between discharge level and pump shaft. Together with suction head (Ha), it forms the total geometric head (Hg = Ha + Hr). Total dynamic head (TDH) further includes distributed and localized friction losses. In the hydraulic design phase, discharge pipe diameter is sized for velocities of 1.5 to 3.0 m/s in low-viscosity liquids, avoiding water hammer and noise. In fire systems, NFPA 20 requires a check valve and isolation valve on the discharge line.

Two scenarios exist: flooded suction (pump below reservoir level, safer for NPSH) and negative suction or suction lift (pump above reservoir, theoretical maximum 10.33 m in water at 20 °C at sea level — practically 6 to 8 m considering losses and NPSH margin). Best practices: suction piping diameter larger than discharge, minimum bends and valves, eccentric reducer before the flange (flat face up) to avoid air pockets and hydraulic eccentricity.

Essential for sizing with variable frequency drives (VFD): reducing speed by 20% reduces flow by 20%, head by 36% and power by 49%, yielding energy savings. Valid for speeds close to nominal (±20%); outside this range, efficiency drops and the models lose accuracy. For impeller diameter variation, valid within the hydraulic family (same casing) and up to ±10% of nominal diameter. In FBCN pumps, impeller trimming is a common field practice to fit the curve to the operating point.

A critical parameter for mechanical sizing of casing and downstream piping: maximum system pressure must account for shut-off + suction pressure, not just the operating point. In acceptance testing (FAT), shut-off is measured as the curve reference. Prolonged shut-off operation is prohibited in centrifugals — generates heating from internal recirculation, potentially vaporizing the liquid in seconds. In fire systems, NFPA 20 limits shut-off to 140% of rated pressure to avoid pipe overpressure.

The scale remains traditional in industrial oil and gear pump catalogs in Brazil and the US, coexisting with the SI centistoke (cSt). Useful references: water is about 31 SSU at 38 °C; above roughly 250 SSU the practical conversion cSt ≈ SSU ÷ 4.62 applies. The FB Bombas FBE line operates up to 100,000 SSU (≈ 21,600 cSt) — the range of asphalt, molasses and resins. Golden rule of specification: always state viscosity at the actual pumping temperature, not the 40 °C catalog figure — in heated fluids, viscosity can drop by orders of magnitude between the cold tank and the heated line.

It is the most common type of industrial pump for low-viscosity liquids at medium to high flow. Ideal for water, aqueous solutions, light solvents, thin fuels and process fluids. FB Bombas' FBCN line follows the ASME B73.1 (mechanical) standard, with back pull-out construction allowing impeller maintenance without disconnecting piping. Variations exist: end-suction (FBCN), double suction, multistage and vertical.

It is the ideal type for viscous fluids — lubricating oils, heavy fuels, asphalt, resins, biodiesel, molasses, chocolate and viscous chemicals. FB Bombas is the original Brazilian manufacturer of this type of pump at industrial scale, continuously operating since 1944. The FBE line has 12 standard sizes from 1/8" to 6", covering flow from 0.5 to 6,500 L/min, pressure up to 22 kgf/cm² and viscosity up to 100,000 SSU with heat-treated alloy steel helical gears.

The main advantage over external gear is practically continuous, low-pulsation flow, making this type ideal for precise dosing, hot-melt applications, polymers, latex and very viscous fluids. FB Bombas' FBEI has 10 catalogued models from 1" to 4" (technical manual MAN001-10) in three construction configurations — with integrated relief valve, compact and heavy-duty 3" — plus the FBEI-LS engineered-to-order version for large capacities in asphalt, bitumen and heavy oils. Standard integrated relief valve and optional heating jacket (steam up to 185°C, thermal fluid up to 232°C, both at 10 bar).

The most important characteristic is that flow depends almost exclusively on rotation — allowing precise dosing. In contrast, centrifugal pumps deliver variable flow with system pressure. Positive displacement pumps must never be operated with closed discharge without a relief valve, under penalty of reaching destructive pressure. The FBE and FBEI lines include an integrated relief valve as optional (FBE) or standard (FBEI).

Dimensional standardization emerged to reduce spare-parts cost and changeover time in industrial plants. FB Bombas' FBCN line is dimensionally compliant with ASME B73.1, with back pull-out construction (removing the rotating assembly without disconnecting piping) and covers flows up to 2,200 m³/h and head up to 135 m, with 53 models (43 standard + 10 large capacity DN150-300). Serves petrochemical, sugar-ethanol, pulp-paper, mining and industrial water treatment. Materials available: cast iron, carbon steel, stainless 304/316, duplex and super duplex, with single or tandem mechanical seal per API 682.

FB Bombas' FBOT line covers applications with synthetic thermal fluids (Therminol, Marlotherm, Dowtherm) and mineral oils, in closed industrial heating systems — sugar-ethanol mills, textile, chemical, food (chocolate), asphalt and oil processing. Critical construction: seal chamber with convection or internal coil cooling, double bearing with oil bath or mist lubrication, alloy steel 4140 shaft, end-suction construction with back pull-out disassembly; when the project demands API 610 requirements, suitability is evaluated requirement by requirement as a special engineering project. Cautions: thermal oil pumps require gradual heating startup (1-2°C/min) to avoid thermal shock in seal and bearings, and operation in systems with expansion tank to accommodate fluid volumetric expansion (~30% between ambient and 300°C).

The big advantage is maintenance time: impeller replacement, mechanical seal inspection and sleeve adjustment are done in hours, not days. It is a requirement of the ASME B73.1 standard for process standardized centrifugals. The FB Bombas FBCN line meets this standard and maintains coupling alignment even after rotating assembly intervention.

It is the preferred option over packing when zero visible leakage, operation with toxic/flammable/high-value fluids, and extended maintenance intervals are required. Configurations include single, double (with barrier fluid), cartridge, balanced and unbalanced. Typical face materials: silicon carbide, tungsten carbide, ceramic. The FBCN line includes 6 sealing chamber configurations (ST, S1, S2, S3, S4 and S) described in the technical manual to serve different fluid/temperature/solids-in-suspension combinations.

Unlike a mechanical seal, packing operates with intentional controlled drip — this small flow is needed to lubricate and cool the rings. It is the economical choice for water, non-aggressive fluids and applications where small leakage is acceptable. FB Bombas technical manuals include the required sealing liquid flow table for each pump size, typically 1 to 5 L/min. Packing requires periodic retightening and replacement every 6-12 months depending on service.

There are three basic centrifugal impeller types by exit angle: radial (blade perpendicular to shaft, high pressure, low flow), mixed-flow (intermediate) and axial (blade parallel to shaft, high flow, low pressure). The FBCN line uses a radial impeller with single suction — suitable for most industrial process applications. For wear resistance in fluids with light solids, there is a pressure-side wear ring (except in smaller models 25-150, 32-125 and 32-125.1).

The volute spiral profile is designed so that fluid velocity drops continuously as the cross-section increases toward discharge — minimizing turbulence losses. The FBCN has a single-piece cast volute in cast iron, A216 WCB carbon steel or A743 CF8M stainless steel, with a suction-side wear ring to maintain ideal clearance even after hours of operation.

The FBCN line uses pairs of ball bearings sized in five frame groups by size range (C3 internal clearance for continuous operation), with oil lubrication via sight gauge or optional automatic refill cup. The FBE line uses self-lubricating TM23 bronze sliding bushings — robust, silent and requiring no external lubrication in normal conditions. Bearing MTBF is one of the main reliability indicators of an industrial pump.

FB Bombas delivers complete motor-pump assemblies for all series (FBCN, FBE, FBEI, FBOT) with WEG motor or equivalent, sized flexible coupling, coupling guard (NR-12) and carbon steel or stainless baseplate. Alignment is done at factory with precision instruments, eliminating the main cause of field-installed pump failure. Motor power reserve follows FBCN manual: 20% up to 2 hp, 15% up to 20 hp, 10% above 20 hp.

Gear pumps (FB Bombas FBE and FBEI) are naturally self-priming — the gear meshing creates sufficient vacuum to draw fluid. Conventional centrifugal pumps (like the FBCN) are not self-priming and require prior priming or a foot valve at suction. The self-priming capability of gear pumps is an important advantage in installations where the pump is above fluid level.

In the FB Bombas FBCN series, the impeller is radial single-suction type with wear ring on the pressure side (except models 25-150, 32-125 and 32-125.1). Impeller diameter defines the head — larger impellers generate more pressure. Available materials: gray cast iron, ductile iron, AISI 316 and AISI 304 stainless steel, Duplex and special alloys upon consultation. The impeller is dynamically balanced at factory to minimize vibrations.

The PRE index (Pitting Resistance Equivalent = %Cr + 3.3·%Mo + 16·%N) classifies the family: Lean Duplex (PRE 25-30), standard Duplex UNS S31803/S32205 (PRE 35), Super Duplex S32750/S32760 (PRE 40+) and Hyper Duplex (PRE 48+). Typical applications: seawater handling, fertilizers (urea, phosphates), paper pulp and chlorinated fluids in refineries. FB Bombas offers Duplex impellers and casings upon consultation for FBCN pumps handling fluids with chlorides > 200 ppm or pH < 4.

Typical application in asphalt pumping, CAP (petroleum asphalt cement), bitumen, animal fats, honey sugar, glycerin, resins and any fluid that solidifies or increases viscosity below a critical temperature. Without jacketing, cold product inside the pump can clog the gears or prevent startup on the next cycle. FB Bombas offers jacketed variants of the FBE line (external gear) — FBE-J — with saturated steam heating at 6-10 bar or thermal oil, sized according to the minimum pumping temperature required by the fluid. In critical assemblies (CAP, bitumen), jacketing extends also to casing, covers and short discharge piping up to the first valve.

ASME B73.1 focuses on the internal mechanics of normalized horizontal centrifugals: mandatory back pull-out construction, minimum 3 mm corrosion allowance, hydrostatic test at 1.5× maximum operating pressure, and minimum clearance between impeller and volute. The FBCN fully meets this standard and all models undergo hydrostatic testing per ANSI B73.1 before shipping.

The standard requires robust construction for continuous 24/7 operation in severe conditions, corrosion and high-temperature resistant materials, redundant sealing for hazardous fluids, and detailed acceptance tests. API 610 pumps are classified by types (OH, BB, VS) according to shaft orientation and construction configuration. FB Bombas has pumps meeting API 610 requirements and is a registered supplier in the CRCC (Supplier Registry) of Petrobras.

The standard requires redundant configuration (main pump + reserve pump + jockey pump for pressurization), independent power source (diesel motor in addition to electric to ensure operation during power loss), certified automatic control panel, and performance curve testing per NFPA. In Brazil, it is complemented by ABNT standards NBR 10897 (sprinklers), NBR 13714 (hydrants) and NBR 16704 (fire pumps). FB Bombas fire-fighting systems fully meet this standard.

NBR 16704 covers sizing of main, jockey and auxiliary pumps, control panels, diesel controllers, hydraulic installation and acceptance testing. Coexists with NFPA 20 in Brazilian projects: state fire departments usually accept both, but large insurer-backed projects require explicit NFPA 20. FB Bombas designs its FBFS skids meeting both NBR 16704 and NFPA 20 requirements, ensuring approval under any regulatory scenario.

The 4th edition (2014) is consolidated as the worldwide reference in refineries and chemical plants. Category 1 covers non-critical services (Type A); Category 2 adds qualification testing (Type A/B/C); Category 3 covers hazardous fluids with severe testing. Flush plans control the seal interface: Plan 11 (simple recirculation), Plan 53 (pressurized barrier-fluid system) and Plan 62 (external quench) are the most common. FB Bombas offers API 610 pumps with sealing sized per API 682, meeting Petrobras CRCC.

The standard covers single-stage process pumps rated up to 16 bar, defining the dimensional envelope per size (discharge DN × nominal impeller diameter) — it is the international counterpart of ASME B73.1 used in the American chemical standard. Important: ISO 2858 is a dimensional standard, not a performance one — it guarantees physical fit, not hydraulic efficiency, which remains defined by each manufacturer's curve. The FB Bombas FBCN line is dimensionally standardized per ASME B73.1, enabling direct drop-in replacement of imported pumps on the same skid without piping rework when the dimensional envelope matches — model-by-model confirmation on the data sheet; a decisive argument in retrofit and plant nationalization.

The registry classifies each supplier by material and service families, and holding the certificate in the right family is a prerequisite for bidding on Petrobras tenders and contracts. The technical assessment examines manufacturing capacity, quality system, traceability and supply history; renewal is periodic and requires sustaining the criteria. For those specifying pumps in oil and gas projects, requiring a supplier with active CRCC reduces late-qualification risk. FB Bombas maintains an active CRCC for its pump lines — one of the credentials behind direct supply to refineries, terminals and units across the Petrobras chain.

The combination of H₂S and free water embrittles high-hardness steels: atomic hydrogen generated at the surface migrates into the metal and causes cracking under stress, even below yield strength. That is why NACE MR0175 caps the hardness of qualified carbon steels (typically ≤ 22 HRC) and lists accepted materials per service regime. In pumps, the requirement reaches casing, shaft, internals, bolting and welds — changing only the casing material is not enough. When specifying pumping of petroleum, naphtha or H₂S-bearing streams, declare the sour condition on the data sheet: engineering selects qualified materials and hardness case by case.

The classification splits gas areas into zones 0, 1 and 2 (from continuous to occasional presence) and dust areas into zones 20, 21 and 22. The Ex marking indicates protection type (for example, Ex d — flameproof enclosure), gas group (IIA, IIB, IIC) and temperature class (T1 to T6, from hottest to coolest allowable surface). Critical point for projects in Brazil: the mandatory certification there is INMETRO's for Ex equipment — technically equivalent to ATEX but legally distinct; equipment carrying only ATEX marking does not meet the Brazilian legal requirement. In motor-pump sets, the classification applies to the motor, instrumentation and electrical accessories, per the zone defined by the hazardous-area design.

The FAT generates a formal signed report documenting results and serving as basis for equipment acceptance. It is mandatory in large projects, Petrobras contracts (CRCC) and critical applications in refineries and petrochemical plants. FB Bombas has its own test bench in Cabreúva-SP with capacity to test all standard models of the FBE, FBEI, FBCN and FBOT lines with calibrated instrumentation and complete documentation.

The main components limiting MTBF in industrial pumps are: mechanical seal (3,000 to 25,000 h), bearings (8,000 to 40,000 h), impeller (depending on erosion and cavitation) and coupling. Best practices to maximize MTBF include operating near BEP, avoiding cavitation, maintaining correct alignment, using adequate lubrication and following the preventive maintenance plan. Robust construction and FB Bombas' design tradition contribute to high MTBF even in severe environments.

The ASME B73.1 standard requires a minimum corrosion allowance of 3 mm for chemical process pumps. FB Bombas' FBCN comes with 3.3 mm corrosion allowance, providing margin above the normative minimum. This margin is critical in moderately corrosive fluids and high-temperature environments that accelerate corrosion rate. For highly corrosive service, more noble materials (316 stainless, duplex) should be used instead of increasing the allowance.

Typical booster pump applications include: public network pressure boosting for tall buildings, boiler feed, fire fighting systems (jockey pump is a type of booster), and industrial process lines where available pressure does not reach the most remote point. FBCN centrifugal pumps are frequently used as boosters in industrial water and sanitation systems.

Consolidated design practice sizes the jockey pump at approximately 1% of main pump flow; NFPA 20 annex A.4.27 covers the pressure-maintenance pump and the setpoint definition method. Its function is to prevent repeated main pump starts that would cause premature wear. Operates with automatic setpoints: starts when pressure drops (e.g., 6.5 bar) and stops upon reaching the upper setpoint (e.g., 7.0 bar). Continuous operation indicates significant system leak. FB Bombas supplies jockeys as integrated part of fire skids.

NBR 13714 requires the device in every hydrant and hose station system: an extension with the same diameter as the main piping (DN 50 to DN 100), with couplings compatible with the local Fire Department; systems above 1,000 L/min get an additional connection. At the sidewalk it sits in a 0.40 × 0.60 m box with a cast-iron cover marked "INCÊNDIO", 0.50 m from the curb, inlet at 45° at most 0.15 m deep; on the façade or wall the inlet sits 0.60 m to 1.00 m from the floor, facing the street and downward at 45°. The valve is gate or ball type, with flow in both directions — unlike the sprinkler fire department connection, which carries a check valve per fire department technical standards. FB Bombas sizes the pump set considering the network the device reinforces.

Typical tolerances (ANSI/ASA): parallel misalignment ≤ 0.05 mm and angular ≤ 0.1 mm/100 mm coupling diameter for speeds up to 1,800 rpm; half those values for 3,500 rpm. Measurement methods in order of precision: straightedge + feeler (rough), dial indicator (industrial standard), laser alignment (precise, recommended by FB Bombas for FBCN and FBOT). Alignment must be verified in two stages: cold (installation) and hot (after thermal stabilization in 30-60 min of operation) — thermal expansion can introduce 0.1-0.3 mm deviations that need pre-compensation.

In centrifugal pumps, the affinity laws make the VFD the most efficient control method: flow varies proportionally with speed, head with the square, and power with the cube — reducing speed by 20% cuts nearly half the consumed power. In positive displacement pumps such as FBE and FBEI, flow is directly proportional to speed, which turns the drive into a precision dosing device. Two specification cautions: respect the minimum speed that guarantees mechanical seal lubrication and cooling, and verify starting torque with viscous or cold fluids. The allowed speed range for each model must be confirmed with the manufacturer's engineering team.

The characteristic rotten-egg odor is detectable at ppm fractions, but the gas numbs the sense of smell at higher concentrations — which makes it treacherous and demands instrumental detection in risk areas. On the materials side, H₂S with free water causes sulfide stress cracking (SSC) in high-hardness steels, the phenomenon that defines NACE MR0175 / ISO 15156 sour service. In sanitation and biogas, dissolved H₂S attacks concrete, cast iron and common elastomers. For pumping H₂S-bearing fluids, specify qualified materials, controlled hardness and tight sealing — a pressurized double mechanical seal where leakage is unacceptable.

Brazilian plants start from vinasse and filter cake in the sugar-energy sector, animal manure, municipal waste in landfills and WWTP sludge. The pumps' role in this process is in the liquids, not the gas: feeding viscous, solids-laden substrate, recirculating and discharging digestate, transferring sludge and draining condensate from gas lines. Residual H₂S and the biologically aggressive environment demand attention to materials and elastomers. Positive displacement pumps handle thick substrates better; centrifugals serve clarified digestate and condensates — operating point and solids content drive the choice.

In Hydraulic Institute and Europump life cycle cost studies, energy and maintenance dominate the TCO of continuously operating pumps — purchase price is usually a minority fraction of the total over 15-20 years of service. The levers that actually reduce TCO: selecting the pump near BEP (efficiency and reliability go together), sizing materials for the real fluid, raising MTBF through alignment and predictive maintenance, and ensuring fast parts replacement — where a domestic manufacturer, with stock and engineering in-country, cuts weeks of downtime. A cheap pump running far from BEP wastes on the energy bill what it saved at purchase.

It differs from corrective maintenance (acting after breakdown) and preventive maintenance (replacing on schedule, even without wear). In pumps, vibration analysis per ISO 10816/20816 identifies unbalance, misalignment and bearing degradation months before failure — each defect has its own spectral signature. Thermography reveals overheating in bearings and motors; lube oil analysis detects wear particles; ultrasound catches incipient cavitation and leaks. The practical result: planned stops instead of emergencies, higher MTBF, and a spares inventory sized by data. Start with the basics done right — laser alignment and balancing — which eliminates the two most common vibration causes.