Industrial pump glossary

NPSH is the absolute suction head above the liquid's vapour pressure. Available NPSH belongs to the system; required NPSH is specified for the pump and its operating conditions.

Available NPSH accounts for absolute pressure, velocity at the suction reference and vapour pressure at the liquid temperature. Compare it with the manufacturer's curve. NPSH3 corresponds to a 3% drop in pump head during testing; it does not mark the onset of cavitation. The necessary margin depends on the pump and application.

Cavitation is the formation of vapour cavities when local liquid pressure drops sufficiently, followed by their collapse in regions of higher pressure.

It can cause noise, vibration, performance loss and erosion. Investigation considers NPSH, temperature, tank level, suction restrictions and operating point. Air entering the piping can cause similar symptoms, so pump noise alone is not a sufficient diagnosis.

Volumetric flow rate is the volume of fluid crossing a section per unit of time. It can be expressed in m³/h, L/min or m³/s, with explicit conversion between units.

For a centrifugal pump, flow results from the interaction between the pump curve and the system. For a positive displacement pump, displacement and speed determine theoretical flow; internal leakage and suction conditions affect actual delivery. Specify the process minimum, normal and maximum flow rates.

Pump head is the energy per unit weight added to the liquid, expressed in metres of the pumped liquid. It is not simply the discharge pressure gauge reading.

The calculation between suction and discharge includes differences in pressure, velocity and elevation. System head includes elevation change, pressure at the starting and delivery points, and hydraulic losses. Converting pressure into head requires fluid density; metres of water column do not represent every liquid.

BEP is a pump's best efficiency point, identified on its performance curve for a specified speed and configuration.

BEP is a reference for assessing the operating point, but does not define every operating limit. Preferred and allowable operating regions depend on pump design, hydraulic conditions and manufacturer guidance. Also check NPSH, power and minimum flow; a single percentage range does not apply to every pump.

A pump characteristic curve describes performance under specified conditions. For centrifugal pumps, it relates flow and head and may include efficiency, power and required NPSH.

Check the model, speed, impeller diameter and reference liquid before comparing curves. Viscosity and operating conditions may require corrections. Selection considers the intersection with the system curve and equipment limits; a curve for another size or speed does not establish the requested model's performance.

Discharge pressure is the pressure measured at the pump outlet. Identify whether it is absolute or gauge pressure and distinguish it from the pressure difference across the pump.

Elevated suction pressure also affects discharge pressure. Pump head is therefore not the maximum allowable casing pressure. Check the pressure and temperature limits of the supplied construction, connections, seal and piping, including transient and blocked-flow conditions considered in the design.

Viscosity describes a fluid's resistance to shear deformation. Dynamic and kinematic viscosity are different quantities related through density.

Provide the value, unit and temperature: cP or mPa·s for dynamic viscosity; cSt or mm²/s for kinematic viscosity. Non-Newtonian fluids may also require shear-dependent data. Viscosity affects losses, power and performance; technology selection also depends on flow, pressure, solids, materials and suction conditions.

Discharge is the outlet side of the pump and the piping carrying liquid to its destination. Its conditions influence the head required by the system.

Sizing considers flow, elevation change, delivery pressure and losses through pipes, valves and fittings. Diameter and velocity should be assessed alongside costs and transient conditions. A discharge pressure gauge reading alone does not represent the total head developed by the pump.

Suction is the inlet side of the pump. Pressure, liquid level, temperature and losses along this section determine the pump's inlet conditions.

Assess available NPSH under the anticipated limiting conditions, whether the source tank is open, pressurised or under vacuum. Air ingress, gas pockets and restrictions can impair supply. Permissible suction lift is not a fixed number: it varies with the liquid, temperature, altitude and installation.

Pump affinity laws estimate how flow, head and power change between similar operating conditions of a rotodynamic pump. Their assumptions and limits must be respected.

For the same impeller, with approximately constant density and efficiency, similar points follow Q ∝ n, H ∝ n² and P ∝ n³. The actual operating point also depends on the system curve. These relations do not guarantee proportional energy savings; impeller trimming, viscosity and cavitation require separate assessment.

Pump shutoff (shut-off) is a centrifugal pump's zero-flow condition: the pump is primed and running, but no liquid flows through it, as with the discharge valve closed. The head at that point, the shutoff head, is read from the curve for the specified speed and impeller.

In manufacturer testing, shutoff is one of the points that define the shape of the curve. Discharge pressure at shutoff also depends on suction pressure and density; do not confuse shutoff head with allowable casing pressure. As an operating condition, the Hydraulic Institute warns that more than a few seconds at shutoff can cause serious mechanical problems, and a closed discharge can heat the liquid; on the FBCN, respect the minimum flow in Table 1 of the manual, 0.1 or 0.15 Qot depending on the bearing frame. For fire pumps, NFPA 20 limits the shutoff head to 140% of rated head for any type of pump. A positive displacement pump, such as the FBE and FBEI gear pumps, does not operate at shutoff: with the discharge blocked, pressure builds until the pump, the piping or the motor fails. It therefore needs a relief valve or, without one, another protection system, such as an in-line valve, a pressure switch or a torque limiter (FBEI manual). The FBE manual includes the relief valve cross-section and parts list (Figure 10 and Table 16).

SSU, or SUS, means Saybolt Universal seconds: the flow time measured in a Saybolt Universal viscometer under specified conditions and temperature.

It is an empirical scale, distinct from cSt or mm²/s. Conversion to kinematic viscosity uses specific relations, such as ASTM D2161, at the corresponding temperature; a fixed divisor does not work across the entire range. Include temperature and fluid identity when submitting SSU data for pump selection.

A centrifugal pump is a rotodynamic pump whose impeller transfers energy to liquid. Performance depends on geometry, speed, fluid properties and the connected system.

Selection matches the pump curve to the process, checking efficiency, power, NPSH and operating range. Impellers, casings and stage counts vary. For FBCN pumps, consult the model documentation and supplied construction; the technology definition does not establish suitability for every fluid.

An external gear pump is a positive displacement pump with two externally toothed gears. Liquid travels between the gear teeth and casing from inlet to outlet.

Theoretical flow follows displacement per revolution and speed; actual flow also depends on internal leakage and inlet supply. Selection considers viscosity, solids, lubricity and material compatibility. For the FBE series, check size and configuration in the manual, including overpressure protection requirements.

An internal gear pump is a positive displacement pump combining an internally toothed gear and an externally toothed gear mounted on offset axes.

In crescent designs, the crescent separates inlet and outlet paths while the gears transport liquid. Pressure, viscosity, temperature, clearances and sealing determine suitability. For FBEI, check the documented construction; heating, valves and materials must not be assumed to be included in every supply.

A positive displacement pump transports fluid volumes through repeated cycles. Geometric displacement determines theoretical flow, not perfectly constant actual delivery.

Gears, lobes and pistons are examples of mechanisms. Speed, internal leakage, viscosity and chamber filling affect delivery. Blocking discharge can rapidly increase pressure; protection must suit the circuit and equipment limits. An integral valve, where fitted, does not replace an assessment of the installation.

A multistage pump has hydraulic stages connected in series. Liquid passes through successive stages that add energy and increase total head.

Adding stages does not multiply flow. Select the assembly using its curve, allowable pressure, power and suction conditions. Comparison with a single-stage pump depends on operating point, fluid and maintenance requirements; neither design is universally superior.

A standardised pump is specified against an identified standard. State the standard, edition and scope: dimensional, construction and performance requirements are not interchangeable.

ASME B73.1 and ISO 2858 are distinct standards with their own scopes; citing one does not establish compliance with the other or automatic interchangeability. The FBCN manual (MTEC-03/00, p. 1) states that the external dimensions generally follow ISO 2858 and that the pump mechanically follows ASME B73.1. For replacement, compare drawings, connections, base, coupling and service conditions of the proposed construction.

A thermal-oil pump circulates heat-transfer fluid through a circuit. Its construction must suit the fluid and the thermal and hydraulic operating conditions.

Operating temperature, startup viscosity, sealing and thermal expansion must be considered together. Consult the FBOT manual limits and procedures for the selected construction. A family's maximum temperature does not permit every fluid, pressure or startup condition, nor does it replace thermal-circuit design.

Back pull-out (back pull out) is a pump construction in which the bearing frame is withdrawn from the back of the casing without disconnecting or misaligning the piping. During maintenance, the casing stays connected to the suction and discharge lines.

At FB, the FBCN and FBOT series use this construction: manuals MTEC-03/00 and MTEC-16/00 (p. 1) describe it and note easier assembly, dismantling and maintenance. The FBEI internal gear pump is also a back pull-out design (FBEI 2026 catalog, p. 3). The FBE external gear pump is not a back pull-out design. Access depends on available clearance and coupling configuration; follow the manual's dismantling and assembly sequence and, after maintenance, check clearances, sealing and alignment as specified. This construction neither removes those checks nor guarantees a fixed maintenance time.

A mechanical seal is a shaft-sealing system using sealing faces, typically one rotating and one stationary, together with secondary seals.

The film between the faces contributes to lubrication and thermal control. Materials, arrangement and support systems depend on pressure, temperature, fluid and process risk. A mechanical seal does not mean absolutely zero leakage, and a single seal is not automatically suitable for toxic, abrasive or flammable service.

Packing is a sealing material compressed in a stuffing box around a shaft or sleeve. Adjustment affects leakage, friction and heat generation.

Depending on the design, controlled leakage is necessary for lubrication and cooling. Tightening until all dripping stops can damage the assembly. Material, adjustment, auxiliary supply and inspection intervals follow the manual and service conditions; there is no single leakage rate or service life for every pump.

A radial impeller discharges liquid predominantly in the radial direction relative to the axis of rotation.

The classification describes flow direction, not simply blade angle. Radial impellers vary in construction, diameter and geometry. Check performance, solids passage and clearances for the specific model; the word radial alone does not define its curve or application.

A volute is the spiral-shaped passage that collects liquid leaving the impeller and guides it to the pump outlet, contributing to conversion of velocity into pressure.

Its geometry is designed together with the impeller and affects hydraulic performance and assembly loads. The casing must also withstand the specified pressure and temperature conditions. Materials and clearances are determined for the model and fluid, not simply by the pump's external shape.

A bearing support locates the shaft and carries loads during rotation. It may use rolling elements or sliding surfaces, depending on the construction.

Type, fit, lubricant and maintenance interval depend on loads, speed and temperature. A bearing code or internal clearance must not be generalised across a whole series. Consult the construction drawing and parts list before purchasing or replacing components.

A pump set combines the pump and its driver with the connecting and supporting components included in the supply. Base, coupling and accessories vary by construction.

Check power, speed, supply, protection, mounting and assembly limits in the proposal. Factory alignment does not remove the need to check after transport, anchoring and piping connection. Motor selection considers the operating range and fluid conditions, not just one nominal point.

A self-priming pump can remove air from the suction line and establish pumping under the priming conditions specified for its design.

Self-priming does not mean dry running is permitted. Depending on the design, the casing may need an initial liquid fill. Suction lift, priming time, temperature and suction-line tightness must comply with the manual. Valves and accessories cannot be omitted without checking the installation.

The impeller is the rotating component that transfers energy to liquid in a rotodynamic pump. Geometry, diameter and speed influence its performance curve.

Open, semi-open and closed designs have different characteristics. When replacing or adjusting an impeller, confirm compatibility with the casing, shaft, clearances and approved curve. Do not extrapolate performance from diameter alone or modify the component beyond manufacturer limits.

Duplex stainless steel is a family of alloys with a microstructure combining ferrite and austenite. Properties vary with grade and manufacturing conditions.

The word duplex alone does not establish resistance to every corrosion mechanism. Assess grade, fluid composition, concentration, temperature and fabrication. When specifying a pump, identify the wetted-part alloy and required documentation rather than selecting material solely by pH or the presence of chlorides.

A heating jacket is a passage designed to circulate a heating medium around parts of the pump, according to its construction.

It can help condition viscous liquids or liquids that solidify on cooling. Heating-medium pressure, temperature and compatibility must remain within construction limits. Confirm the system specified for the model in its catalog and proposal.

ASME B73.1 is a specification for horizontal end-suction centrifugal pumps for chemical processes. Its scope includes construction and dimensional aspects.

The FBCN manual (MTEC-03/00, p. 1) states that the pump mechanically follows ASME B73.1 and that its external dimensions generally follow ISO 2858. The purchase specification should identify the applicable edition, construction and documentation requirements. Neither reference alone establishes API 610 compliance or complete interchangeability; compare drawings and service conditions.

API 610 is a standard for centrifugal pumps used in petroleum, petrochemical and natural gas industries. It establishes equipment and specification requirements.

The standard covers different pump constructions. Its edition, process data, tests and documentation should be identified in the project specification. Mentioning API 610 in an enquiry does not establish that every model complies; verify the proposed supply against the applicable requirements.

NFPA 20 addresses the installation of stationary pumps for fire protection. Application depends on the design, adopted edition and authority having jurisdiction.

Selection considers hydraulic demand and the system's pump, driver, control and installation requirements. A universal three-pump arrangement must not be assumed. Referencing the standard does not automatically certify a pump set; documentation and acceptance criteria must correspond to the project.

ABNT NBR 16704 specifies requirements for stationary pump sets intended for automatic fire protection systems in Brazil.

The responsible professional should confirm the edition and its applicability alongside local fire authority requirements. Merely citing the standard does not guarantee approval throughout Brazil or full equivalence with another standard. Include project requirements and required documents in the commercial enquiry.

API 682 is a standard for shaft-sealing systems for centrifugal and rotary pumps. It addresses the sealing system rather than complete pump compliance.

Selection matches the seal and its support systems to process conditions and risks. Provide fluid, pressure, temperature, emissions and operating requirements. A commercial reference to a mechanical seal does not establish API 682 compliance; specify the edition, configuration and documentation.

ISO 2858 specifies the designation, nominal duty point and principal dimensions of end-suction centrifugal pumps with a maximum operating rating of 16 bar.

The FBCN series technical manual (MTEC-03/00, p. 1) states that the external dimensions generally follow ISO 2858 and that the pump mechanically follows ASME B73.1. This dimensional reference is not a certification; it does not establish hydraulic performance or chemical compatibility and does not guarantee interchangeability with another pump. For replacement, compare the drawings, flanges, baseplate and coupling of the proposed construction with those of the installed equipment.

CRC is Petrobras's supplier registration certificate, the name that replaced CRCC. It records registration status for the assessed supply families.

The certificate has a defined scope and validity; it is not technical certification of every pump or automatic approval of an offer. If required for a purchase, request the current document and check the relevant supply family. A historical reference does not establish a supplier's current status.

Sour service describes service containing H₂S under conditions that can cause specific material-degradation mechanisms, particularly in aqueous environments.

ISO 15156 addresses materials for H₂S-containing environments in oil and gas production; it must not be extended automatically to every refining process. Selection depends on temperature, composition, H₂S partial pressure and material. A single hardness or concentration limit does not establish suitability.

ATEX refers to European directives concerning equipment and workplaces with potentially explosive atmospheres. Products and their use are subject to distinct requirements.

Directive 2014/34/EU concerns equipment and protective systems; 1999/92/EC concerns worker protection. Specification depends on area classification and ignition risks, including non-electrical sources. Do not assume automatic equivalence between ATEX documentation and requirements in the installation country.

FAT means Factory Acceptance Test: acceptance testing at the factory against an agreed scope and criteria for the supply.

The plan identifies the test scope, procedures, instruments, criteria, records and any customer witnessing. Hydraulic, mechanical and documentary checks are not automatically one package. Whether FAT is required, and what it includes, depends on the contract and applicable requirements rather than every pump having a universal test package.

MTBF is mean time between failures for repairable equipment, estimated from defined data and conditions. It is not a guaranteed service life for an individual pump.

When comparing results, identify the population, period, operating hours and definition of failure. Fluid, installation and maintenance regime influence the comparison. Without these data, an MTBF figure does not establish that a series is more reliable or will operate that long without intervention.

Corrosion allowance is additional thickness included in a design to accommodate material loss from corrosion under the anticipated service conditions.

Its value depends on the specification and construction and must not be assigned to an entire family without documentation. Extra thickness does not replace chemical compatibility assessment or address every corrosion mechanism. Evaluate material, concentration, temperature and design life together.

A booster pump increases the pressure available in a system. The term describes its function rather than a single hydraulic design.

Selection considers required flow, varying inlet pressure and delivery pressure. Check pump and network limits throughout the operating range, together with the control strategy. Adding a pump without assessing its supply can compromise suction conditions.

A jockey pump maintains pressure in a fire protection system. It compensates for anticipated small losses to avoid unnecessary starts of the main fire pump.

It does not replace the pump supplying fire demand. Flow, pressure and start/stop settings depend on network characteristics and the approved design criteria. A fixed percentage of main-pump flow is not a universal sizing rule. Confirm the applicable standard and authority requirements.

A fire department connection allows firefighters to supply water to a building's fire protection system from external pumping equipment.

It is a network interface, not the fire pump or a public water-supply hydrant. Location, access, identification and connections follow the design and local authority instructions. One jurisdiction's rules should not be presented as universal dimensions or conditions for all installations.

Alignment adjusts the relative positions of the pump and driver shafts. It considers parallel and angular deviations within the applicable assembly tolerances.

Foundation, anchoring, piping loads and thermal expansion can change alignment. Check the installed assembly and after interventions, following pump and coupling instructions. Laser or dial-indicator measurements do not remove the need to correct the causes of misalignment; tolerances and thermal targets are not universal.

A VFD is a variable-frequency drive that controls an electric motor's supply to adjust speed within the drive system's limits.

In pumping, it can match operation to demand when motor suitability, cooling, speed range, NPSH and the system curve are checked. Savings depend on duty profile and assembly losses, not a guaranteed percentage from speed reduction. Positive displacement pumps require their own pressure and torque assessment.

H₂S is hydrogen sulfide, a toxic and flammable gas that can occur in industrial processes. Odour is not a reliable means of detecting its presence.

Processes involving H₂S require professional risk assessment, exposure control and appropriate detection. For pumps handling liquids containing it, provide composition, pressure and temperature. Materials, sealing and containment must be assessed for the service; an alloy or series name does not establish suitability.

Biogas is a gas mixture produced by anaerobic decomposition of organic matter, mainly containing methane and carbon dioxide with other variable components.

A plant may need pumps for process liquids, but this does not mean a liquid pump handles biogas itself. For each circuit, identify the actual fluid, solids, fibres, viscosity, corrosiveness, flow and pressure. The application sector alone does not determine the pumping technology.

TCO is the total cost of owning equipment over a defined period. It includes purchase and the relevant costs of installation, operation, maintenance and retirement.

For pumps, comparison may include energy, parts, labour and downtime consequences. Use the same demand, evaluation period, annual hours and pricing assumptions for alternatives. Energy and maintenance do not always represent the same share; estimates should reflect the process and be reviewed against operating data.

Predictive maintenance uses equipment-condition monitoring and trends to guide interventions rather than relying only on fixed intervals.

Vibration, temperature, lubricant and hydraulic performance can provide complementary signals. Diagnosis needs a baseline, comparable measurement conditions and history analysis. No single measurement guarantees prediction of every failure; combine criticality, manufacturer recommendations and inspection and action criteria.