Gear Pumps (External & Internal)
When you need steady, low-pulse flow on clean, lubricating fluids across a wide viscosity range, gear pumps shine. They deliver predictable displacement, excel on oils, fuels, polymers, and adhesives, and can be jacketed for heat-trace service. We size external and internal gear designs with the right elastomers, and drives for your temperature and duty cycle.
- Positive displacement for accurate flow vs. speed; great for batching and transfer
- Handles thin to very viscous (select clearances & speed) with smooth output
- Options for heating jackets, pressure relief, and bi-directional service
- Best on clean, lubricating fluids; abrasion requires special consideration
Manufacturers We Represent for Gear
Featured Gear Products
What Makes Gear Different (and When It Beats Other Pumps)
How Gear Pumps Work
- External gear: two meshing gears trap and move fluid around the casing.
- Internal gear: inner/outer gear with crescent—great suction & high viscosity handling.
- Displacement is proportional to speed—excellent for batching and tight process control.
Where Gear Wins
- Lube oils & fuels (diesel, fuel oil, lube skids) with smooth, low-ripple flow
- Viscous products (polymers, resins, adhesives, asphalt) with heat-jacket options
- Metering/transfer where repeatability and steady flow matter
- Clean-fluid services where abrasive wear is minimal
Best-Fit Gear Configurations by Service
| Service | Ideal Configuration | Recommended Brands | Why It Works |
|---|---|---|---|
| Lube oil circulation / transfer | External gear, close clearances; mechanical seal; pressure relief | Roper • Gorman-Rupp | Stable, low-pulse flow; good on thin, lubricating fluids |
| Heavy polymers, resins, adhesives | Internal gear w/ heating jacket; enlarged ports; reduced speed | Roper | Excellent suction; handles high viscosity with temperature control |
| Fuel oil / diesel loading | External gear with built-in relief; NEMA motor or explosion-proof as required | Roper • Gorman-Rupp | Repeatable displacement; easy VFD control |
| Asphalt / bitumen | Jacketed internal gear; high-temp seals; thermal relief loop | Roper | Heat trace keeps viscosity in range; gear geometry handles thick products |
| Alternative to gear for dirty/variable fluids | Sliding vane (alt) with ductile iron casing | Blackmer (alt) | Vanes tolerate mild solids & viscosity swings; great suction lift |
Sizing inputs: flow & discharge pressure, viscosity at operating temp, fluid lubricity/cleanliness, temperature range, duty cycle, environment (hazardous/sanitary).
Materials & Performance
Construction & Sealing
- Metals: cast iron, ductile iron, carbon steel, 316SS (chemicals/food)
- Clearances: set to viscosity & temperature; hardened gears for wear resistance
- Seals: mechanical seal, packed box; double-seal options; mag-drive gear available in select lines
- Heating: jacketing on casing/cover to manage high-viscosity or solidifying products
Real-World Ranges
- Flow: fractional GPM to hundreds (model dependent)
- Differential pressure: commonly to 150+ PSI on suitable builds
- Viscosity: from water-like to very heavy (temperature & speed permitting)
Accessories That Make Gear Installs Bulletproof
- Integral or inline relief valves (protects pump from dead-head)
- Suction strainers sized to velocity to protect gears without starving the inlet
- VFD & instrumentation for speed/flow control, pressure & temperature feedback
- Thermal management (jackets, heat tracing) to keep viscosity in the design window
- Baseplates & alignment kits to control vibration and seal life
Gear vs. Other Common Pump Types
| Use Case | Gear | Progressive Cavity | AODD | Centrifugal | Peristaltic |
|---|---|---|---|---|---|
| Clean lube oils & fuels | Excellent | Good | Good | Good (steady suction) | Fair |
| Very viscous resins | Great (internal gear) | Great | Good | Poor | Good |
| Abrasive solids present | Fair/Poor (wear) | Good | Good | Poor | Good |
| Low-pulse metering | Excellent | Good | Fair | Fair | Good |
| Self-priming / run-dry | Fair (short-term) | Fair | Excellent | Fair | Excellent |
What We Need to Size Your Gear Pump
- Duty point: target GPM & differential pressure
- Fluid: SDS, viscosity vs. temperature curve, lubricity, cleanliness (filtration)
- Temperature: operating & startup; need for jacketing or heat trace
- Seal strategy: single/double mechanical, packed, or sealless requirement
- Environment: hazardous area, washdown/sanitary, footprint & utilities
Top Gear Lines We Stock (Placeholders)
Send your duty point & fluid—We’ll return clearances, seal plan, jacket needs, and a complete BOM.
Send Us Your Fluid & Duty—We’ll Match the Gear Pump in Minutes
We’ll set clearances, seal plan, jackets, and drive to your viscosity and pressure—fast quote, curve, and BOM included.
Gear Pump FAQs
External vs. internal gear—how do I choose?
External gear excels on clean, thin to medium viscosity, higher pressure. Internal gear offers better suction and handles very viscous products, especially with heating jackets.
Do I need a relief valve with a gear pump?
Yes—positive displacement pumps require integral or inline relief protection to prevent over-pressure when a valve is closed or a line plugs.
Can gear pumps run abrasive slurries?
They are best on clean, lubricating fluids. Abrasives wear gears and bushings; for solids or variable fluids we often recommend sliding vane (Blackmer) or progressive cavity.
What about temperature swings and viscosity change?
We set clearances to your operating window and can add jacketed casings and VFD control so flow stays within spec as viscosity changes.
Which seals are typical on gear pumps?
Mechanical seals (single/double) or packed box are common. For emissions or difficult fluids, some lines offer mag-drive sealless gear options.