Types and operation of the Gear Pump

A gear pump is a positive displacement pump: fluid travels through the spaces between the teeth and casing from suction to discharge. Geometric displacement per revolution is theoretical; delivered flow varies with speed, pressure, viscosity and internal slip. FB Bombas manufactures the FBE external gear and FBEI internal gear series. Selection uses model tables and curves under actual process conditions.

In the FBE, externally toothed gears operate inside the casing. The FBEI internal gear arrangement uses a rotor, internal gear and crescent separator. Construction alone does not determine the better pump: compare flow, differential pressure, viscosity at operating temperature, suction, seals and materials. Operating limits and accessories are model-specific; neither series should be assigned a universal pulsation or efficiency range.

FBE and FBEI serve applications with oils, asphalt, resins, adhesives and other liquids whose compatibility is confirmed. Provide composition, solids, viscosity and temperature to select materials, sealing and speed. The FBE viscosity table has size-specific limits; stainless steel is not compatible with every corrosive product.

The FBEI catalogue states that the FBEI is self-priming; the FBE manual and catalogue do not address self-priming, so engineering confirms suction case by case. Self-priming does not permit dry running. The FBEI manual requires fluid inside the pump and air removal around the seal before startup. Check suction tightness, filter losses, viscosity, rotation direction and model instructions; suction capability is not a fixed lift valid for every process.

The range depends on size, configuration and speed. Table 1 of the FBE manual lists up to 6,550 L/min for the 6″ FBE at 500 rpm under the stated table conditions. The pressure limit reaches 22 kgf/cm² on smaller sizes and varies by size. These maxima do not represent one operating point. Check flow at the required pressure, viscosity limits by size, materials and seals. The CA heating chamber is available from 1.1/2″ to 6″; it does not replace thermal validation of the assembly.

Selection between gear and centrifugal pumps depends on flow, pressure or head, viscosity at operating temperature, suction conditions and materials. FBE and FBEI serve viscous fluids; FBCN serves centrifugal applications and FBOT thermal oil circuits. There is no universal 100 cP threshold: compare corrected curves, internal losses and power at the same duty point with engineering.

Replacement can be assessed using the nameplate, drawings and process data: fluid, flow, pressure, viscosity and temperature. Engineering compares the curve, materials, sealing, drive and interfaces to define the FB configuration. Modifications, lead time and pump and spare-part availability should be included in the proposal.

A gear pump displaces a theoretical volume per revolution. Actual flow depends on speed and internal slip, which varies with pressure and viscosity. Selection must use the model data at the required duty point.

Gear pumps relate flow to speed, allowing for internal slip, and serve viscous-fluid applications. Comparison with other positive displacement pumps must use the same fluid, temperature, pressure and flow, alongside power, maintenance and material compatibility. The FBE series has different configurations and seals, including a seal with Viton documented in its manual. Universal superiority or longer service life cannot be promised without comparable duty data.

The filter must follow the series manual and fluid assessment. For the FBEI, the manual specifies 40–80 mesh depending on the model, with ample flow area. Check pressure loss at operating fluid temperature and the effect of blockage on suction. This specification must not be transferred automatically to every FBE. For suspended solids, consult FB Bombas about abrasiveness, particle size and assembly suitability.

Reversible operation depends on pump and circuit configuration. The FBEI manual requires checking the specified rotation direction and orienting the relief valve toward suction. Reversing the motor supply alone is insufficient: suction, discharge, seals and overpressure protection must remain compatible with the new direction. Confirm the model configuration with engineering before reversible operation.

Theoretical flow increases with speed, but delivered flow also depends on pressure, viscosity and internal slip. Use FBE Table 1 for flow and Table 2 for speed according to viscosity and size. The documented range extends from 1,750 rpm down to 150 rpm depending on the case, with a suitable pulley drive or gearbox. Do not impose a universal minimum speed or extrapolate flow without checking the model and suction conditions.

Components differ between series. The FBE uses a casing, covers, gears, shafts supported by bushings and packing or a mechanical seal depending on configuration; a rolling bearing appears in the optional external bearing arrangement. The FBEI has a rotor and rolling bearing documented in its own manual. Heating chamber, relief valve and drive depend on the model. Use the series exploded view and parts list to identify components and order replacements.

The drive must provide the speed and torque required by the model at start-up and in operation. The FBE manual presents motor, pulley or gearbox options according to viscosity range. Confirm the motor, transmission, baseplate, coupling, guard and assembly and test scope in the proposal; these items should not be assumed for a bare pump.

Online catalogs and PDF technical manuals are available on the FBE and FBEI pages and in the manuals section. Use the document matching the series and configuration for tables, dimensions, materials and instructions. Model pages organize current and earlier records; engineering confirms configuration and availability for the process.

For 3″, the FBE catalog lists FBE 3″ and FBE 3″ M9 configurations, with an optional CA heating chamber. DA does not identify a 3″ variant. Select the configuration using flow at the required pressure, viscosity at pumping temperature, speed and suction conditions. The specification page and manual Table 1 identify the model; send process data to engineering to validate materials, seals and drive.

Selection requires assessing fluid, solids, abrasiveness, temperature, pressure, flow and seal materials for both alternatives. FBE and FBEI serve gear-pump applications; this does not establish superiority for every viscous fluid. The FBE manual requires consulting FB for suspended solids. Compare the proposed progressive cavity model with the gear pump under the same duty conditions. FB Bombas manufactures gear pumps and does not manufacture progressive cavity pumps.

In the FBE series, yes. The FBE 2026 catalogue (p.3) lists the casing and covers in ASTM A48 CL30 cast iron, ASTM A536 60-40-18 ductile iron, ASTM A216 WCB carbon steel or ASTM A743 CF8M stainless steel; shafts and gears in SAE 1045 steel or AISI 316L stainless steel, with special treatments on request; and the relief valve in brass or AISI 304 stainless steel. Stainless steel is not compatible with every corrosive product: the choice depends on the composition, concentration and temperature of the liquid.