Industrial gear pumps provide precise, pulse-free flow for lubrication systems, hydraulic power units, fuel transfer, and high-viscosity oil applications. These positive displacement pumps offer consistent flow regardless of pressure, making them ideal for lubrication and hydraulic systems where reliability is critical. This guide covers gear pump selection, types, lubrication system design, and maintenance.
Gear Pump Applications
| Application | Service | Typical Spec | Pump Type |
|---|---|---|---|
| Lubrication system | Circulate oil to bearings/gears | 10โ500 L/min, 5โ40 bar, clean oil | Internal gear or external gear |
| Hydraulic power unit | Supply pressurized oil to actuators | 20โ500 L/min, 100โ350 bar | External gear or piston pump |
| Fuel oil transfer | Transfer diesel, heating oil, heavy fuel | 50โ2000 L/min, 3โ20 bar | Internal gear or screw pump |
| Heavy fuel oil (HFO) | Transfer and booster for boilers | 50โ1000 L/min, 10โ50 bar, heated | Internal gear (jacketed) |
| Transformer oil | Fill/drain, filtration, circulation | 10โ200 L/min, 3โ10 bar | Internal gear (cast iron/316SS) |
| Polymer/bitumen | High-viscosity, heated transfer | 10โ500 L/min, 20โ100 bar, 150โ250ยฐC | Jacketed internal gear |
| Chemical metering | Precise additive injection | 0.1โ50 L/min, 10โ100 bar | Gear metering or diaphragm metering |
| Coolant circulation | Machine tool coolant | 20โ200 L/min, 3โ15 bar | External gear or centrifugal |
Critical: Internal vs External Gear Pumps
| Feature | Internal Gear | External Gear |
|---|---|---|
| Design | One internal gear (ring) + one external gear (spur) | Two external gears (spur) meshing |
| Pulsation | Lower (smoother flow) | Higher (more pulsation) |
| Speed | Lower (100โ1000 RPM typical) | Higher (500โ3000 RPM) |
| Viscosity range | Wider (1โ1,000,000 cP) | Moderate (1โ10,000 cP) |
| Pressure | Up to 150 bar | Up to 350 bar (hydraulic) |
| Flow rate | Up to 500 mยณ/h (large) | Up to 200 L/min (typically smaller) |
| Noise | Quieter | Louder (gear meshing) |
| Cost | Higher | Lower |
| Best for | High viscosity, low pulsation, large flow | Hydraulic, high pressure, small flow |
Critical: For lubrication and oil transfer, internal gear pumps are preferred โ wider viscosity range, lower pulsation, quieter, handle high-viscosity oils (including heated HFO and polymers). External gear pumps are standard for hydraulic power units (high pressure, compact, cost-effective). Our internal gear pumps cover lubrication, fuel oil, and high-viscosity applications.
Critical: Lubrication System Design
- System components: (1) Oil reservoir (tank with baffles, heater, level gauge), (2) Pump (gear pump, typically 2ร required flow), (3) Filter (pressure filter 10โ25ฮผm, return filter), (4) Cooler (water-cooled or air-cooled heat exchanger), (5) Pressure relief valve (bypass, protects pump/system), (6) Distribution manifold (to bearings/points), (7) Flow meters/switches (verify flow to each point), (8) Temperature/pressure sensors (monitoring), (9) Return line (back to reservoir).
- Pump sizing: Gear pump flow = displacement ร speed ร volumetric efficiency. Size pump for 1.5โ2ร required flow (account for wear, viscosity changes, filter pressure drop). Use relief valve set at 1.2ร system pressure. Our engineering team sizes lubrication pumps.
- Redundancy: Critical lubrication systems (turbines, compressors, large gearboxes) use dual pumps (1 operating + 1 standby) with automatic switchover on pressure loss. AC + DC power (battery backup) for emergency lubrication during power loss. Our systems include redundancy design.
- Oil conditioning: Lubricating oil must be clean (ISO 4406 cleanliness code), dry (water ๏ผ100 ppm), and at proper temp (40โ60ยฐC typical). Filters, dehydrators, and coolers maintain oil condition. Gear pumps are sensitive to contamination โ use proper filtration (10โ25ฮผm suction, pressure filter).
Critical: Hydraulic System Gear Pumps
| Parameter | Typical Value | Notes |
|---|---|---|
| Pressure | 100โ350 bar | Standard hydraulic; high-pressure systems use piston pumps |
| Flow | 10โ200 L/min | Gear pumps limited to smaller flows |
| Speed | 1000โ3000 RPM | Direct drive from electric motor or engine |
| Displacement | 1โ100 cc/rev | Fixed displacement (gear pumps are fixed) |
| Fluid | Mineral oil, synthetic, fire-resistant | Viscosity 10โ400 cP typical |
| Filtration | 10โ25ฮผm (pressure), 25ฮผm (return) | Critical for gear pump life |
| Temperature | 20โ80ยฐC (oil) | Above 80ยฐC accelerates wear |
Critical: Gear pumps are fixed-displacement โ flow is constant at a given speed. For variable-flow hydraulic systems, use a pressure relief valve (bypass excess flow) or a variable-displacement piston pump. Gear pumps are simple, reliable, and cost-effective for constant-flow hydraulic systems. Our external gear pumps meet hydraulic system requirements.
Critical: High-Viscosity and Heated Oil Service
- Heavy fuel oil (HFO): Viscosity 100โ1000 cSt at 50ยฐC, must be heated to 80โ150ยฐC for pumping. Use jacketed internal gear pump (steam/hot oil jacket) with heat-traced piping. Maintain oil temp at burner viscosity spec (typically 10โ20 cSt at burner). Our jacketed pumps and internal gear pumps handle HFO.
- Polymer/bitumen: Viscosity 10,000โ1,000,000 cP, temp 150โ250ยฐC. Use jacketed internal gear pump with gearbox reduction (low speed 50โ200 RPM). Precision gears for metering. Our jacketed gear pumps handle polymers.
- Speed reduction: High-viscosity fluids require reduced pump speed โ at high speed, viscous drag causes excessive power and cavitation. Use gearbox (5:1 to 15:1 reduction). Rule: speed โ 1/โviscosity. Our pumps include gearbox options.
Critical: Common Problems
- Problem 1: Pump wear (contamination). Dirty oil โ gear/bushing wear โ increased clearance โ reduced flow/pressure โ system failure. Solution: proper filtration (10โ25ฮผm),ๅฎๆ oil analysis, clean reservoir, breathers. Our systems include proper filtration.
- Problem 2: Cavitation (high viscosity). High-viscosity oil + small suction line โ NPSHa low โ cavitation โ noise, damage. Solution: larger suction piping, flooded suction, reduce speed, heat oil (lower viscosity), low NPSHr pump. Our systems include proper suction design.
- Problem 3: Relief valve failure. Relief valve stuck closed โ overpressure โ pump/piping failure. Solution:ๅฎๆ test relief valve, install pressure gauge, spare valve, proper sizing. Our systems include relief valve testing.
- Problem 4: No flow (air lock). Air in suction line โ pump loses prime โ no flow. Solution: flooded suction, vent pump, foot valve, proper piping (no high points), self-priming design. Our internal gear pumps are self-priming.
- Problem 5: Overheating (low flow). Pump running against closed valve (dead-headed) โ no flow โ heat buildup โ oil degradation, seal failure. Solution: relief valve (bypass flow), temperature sensors, never dead-head, minimum flow recirculation. Our systems include protection.
- Problem 6: Seal leakage. Mechanical seal wears โ oil leak โ contamination, fire risk. Solution: magnetic drive (zero leakage) for hazardous oil, double mechanical seal,ๅฎๆ seal maintenance, proper oil condition. Our magnetic drive options eliminate leakage.
Selection Summary
- Lubrication system (clean oil, 5โ40 bar): Internal gear pump (low pulsation, quiet, wide viscosity, dual pump redundancy)
- Hydraulic power unit (100โ350 bar): External gear pump (high pressure, compact, cost-effective, fixed displacement)
- Fuel oil transfer (diesel, heating oil): Internal gear pump (cast iron or 316SS, self-priming, 3โ20 bar)
- Heavy fuel oil (HFO, heated): Jacketed internal gear pump (steam/hot oil jacket, gearbox reduction, 80โ150ยฐC)
- Polymer/bitumen (very high viscosity): Jacketed internal gear pump (precision gears, low speed, 150โ250ยฐC)
- Transformer oil (clean, low pressure): Internal gear pump (cast iron/316SS, 3โ10 bar, self-priming)
- Chemical metering (precise): Gear metering pump or diaphragm metering (ยฑ1%, zero leakage)
- Hazardous/zero leakage: Magnetic drive gear pump (no seal, safe for flammable oil)
- Critical: gear pumps = POSITIVE DISPLACEMENT (constant flow regardless of pressure, precise) + INTERNAL GEAR (wide viscosity 1โ1M cP, low pulsation, preferred for oil/lubrication) vs EXTERNAL GEAR (high pressure 100โ350 bar, hydraulic systems) + LUBRICATION SYSTEM (reservoir, filter, cooler, relief valve, redundancy, oil conditioning) + HIGH VISCOSITY (jacketed pump, gearbox reduction, heat oil) + FILTRATION (10โ25ฮผm critical for gear life), all = reliable lubrication/hydraulic operation + equipment protection + long service life
- Our internal gear pumps, external gear pumps, jacketed pumps, and metering pumps cover lubrication and hydraulic applications. For gear pump selection, talk to our engineers with your fluid viscosity, temperature, flow, pressure, and application (lubrication/hydraulic/fuel).