Gear Pumps

A gear pump is a type of positive displacement pump that uses the meshing of gears to pump fluid by displacement. They are compact, relatively simple in design, and capable of handling viscous fluids and delivering high pressures, making them widely used in various industrial applications.

Types of Gear Pumps

External Gear Pumps: Have two identical, externally meshing gears. The most common type.

Internal Gear Pumps: Have an internal gear that meshes with an external spur gear (rotor and idler). Often used for high-viscosity fluids.

Gerotor Pumps: A type of internal gear pump with a specific geometry, often used in automotive oil pumps.

Crescent Gear Pumps: An internal gear pump with a crescent-shaped partition.

Lobe Pumps: Similar to gear pumps but use lobes instead of gears, suitable for shear-sensitive fluids and slurries. (Sometimes grouped with gear pumps due to similar operating principle).

Applications in Various Industries

Hydraulic Power Units: As hydraulic pumps in industrial machinery, mobile equipment, construction equipment, agricultural machinery.

Lubrication Systems: Pumping oil for lubrication in engines, gearboxes, turbines.

Fluid Transfer: Pumping fuel oil, crude oil, asphalt, resins, paints, solvents.

Chemical Processing: Metering and transfer of chemicals.

Food & Beverage: Transfer of syrups, chocolate, edible oils (with hygienic designs).

Extrusion & Polymer Processing: Pumping molten polymers from extruders to dies.

Oil & Gas: Transfer pumps, booster pumps.

Material Selection Considerations

Casing/Housing:

• Cast Iron: Common for general industrial applications, good strength and vibration dampening.
• Ductile Iron: Improved strength and ductility over cast iron.
• Stainless Steel (304, 316, 316L): Essential for corrosive fluids, hygienic applications (food, pharma), and high temperatures.
• Bronze: For marine applications, good corrosion resistance to saltwater.
• Aluminum Alloys: For lightweight applications.

  Gears:

• Hardened Steel Alloys (e.g., alloy steel, case-hardened steel): For strength, wear resistance, and high-pressure applications.
• Stainless Steel: For corrosive fluids.
• Bronze/Brass: For non-sparking applications or when dissimilar metals are desired to prevent galling.
• Engineering Plastics (e.g., PEEK, PTFE, Carbon-filled PTFE): For pumping corrosive chemicals, very low friction, or when self-lubricating properties are needed, though with lower pressure/temperature limits.
• Shafts: Hardened steel or stainless steel for strength and wear resistance.

  Bearings/Bushings:

• Bronze (e.g., leaded bronze, phosphor bronze): Good bearing properties, wear resistance.
• Carbon Graphite: Self-lubricating, chemically resistant, high temperature.
• PTFE composites: Low friction, chemical resistance.
• Ceramics: For highly corrosive or abrasive applications.

  Seals:

• Elastomers: Nitrile (Buna-N), Viton (FKM), EPDM, PTFE for O-rings, lip seals, chosen for chemical compatibility and temperature range.
• Mechanical Seals: Faces made of ceramic, silicon carbide, tungsten carbide for abrasive/high-pressure applications.
• Gaskets: Compressed non-asbestos fiber, PTFE, graphite.