External Gear Pumps
External gear pumps are positive-displacement pumps used for accurate, repeatable transfer of clean, low to high viscosity liquids—especially oils, fuels, resins and many industrial fluids. They’re valued for steady flow, good controllability, and simple, robust construction.
What are external gear pumps and how do they work?
An external gear pump uses two meshing gears rotating inside a close-fitting casing:
1. As the gears unmesh at the inlet, they create a low-pressure zone that draws liquid into the pump.
2. The liquid becomes trapped between the gear teeth and casing and is carried around the outside of the gears.
3. At the outlet, the gears mesh, reducing volume and forcing liquid out at pressure.
Because they’re positive displacement, flow is roughly proportional to speed, and they can generate higher pressures than many dynamic pumps (within the pump’s rated limits).
External Gear Pump Typical applications
• Oil and lubricants: lube oil transfer, filtration loops, hydraulic oils (duty dependent)
• Fuels and hydrocarbons: diesel, fuel oils, kerosene and solvents (materials dependent)
• Resins, polymers and adhesives: consistent transfer of viscous fluids
• Chemical transfer: compatible clean chemicals where solids are minimal
• Dosing / metering-style transfer: where stable flow is needed (often with a VFD)
(External gear pumps generally prefer clean, low-solids fluids; abrasives can accelerate wear due to tight clearances.)
Why buy external gear pumps from Triark?
Triark can support pump selection, spares supply and aftercare—helping you match the right gear pump to viscosity, temperature, flow, pressure, and materials compatibility, then supporting uptime with the correct service parts and technical guidance.
External gear pump spares and service
Common wear/service items include:
• Shaft seals (mechanical seal or lip seal, model dependent)
• Bushings/bearings
• Gears and wear plates (clearance-related wear)
• O-rings/gaskets
• Relief valve components (if fitted)
Repair and maintenance
Good practice includes:
• Use filtration/strainers to protect tight clearances
• Monitor for declining flow at constant speed (often indicates internal wear/slip)
• Avoid running dry and ensure good suction conditions to prevent cavitation and seal issues
• Confirm pressure protection is in place (internal relief valve where fitted, or external relief/bypass)
