Gear Pumps Selection Guide: Working Principle, Types & Industrial Applications

What is the Working Principle of a Gear Pump?

The working principle of a gear pump involves the use of rotating gears which mesh to create a vacuum at the pump inlet. This vacuum draws the fluid into the spaces between the gear teeth. As the gears rotate, the fluid is trapped and carried around the outer casing from the suction side to the discharge side.

Unlike a Centrifugal End Suction Pump which uses velocity to move fluid, a rotary gear pump uses mechanical force to “push” the liquid out. The mesh of the gears on the discharge side displaces the fluid, forcing it into the outlet pipe. Because the volume per revolution is fixed, the pump delivers a steady, pulse-free flow.

Types of Gear Pumps

Gear pumps are either external or internal based on their design and operation.

External Gear Pump

External gear pumps utilize two identical gears with external teeth to generate flow. The rotation of the gears is such that the liquid comes into the inlet port and flows into and around the outer periphery of the two rotating gears. As the liquid comes around the periphery it is discharged to the outlet port.

External gear pumps have close tolerances and shaft support on both sides of the gears. This allows them to run to pressures beyond 3,000 psi / 200 bar and also provide greater flow control and a more reliable measure of liquid passing through a pump. It also means they are not well suited to handling abrasive or extreme high temperature fluids. Slippage, which reduces efficiency and flow, increases as viscosity decreases and approaches zero at 5000 SSU (Saybolt Universal Seconds).

Internal Gear Pump

Internal gear pumps generate flow using a gear with externally-cut teeth contained in and meshed with a gear with internally-cut teeth. As the gears come out of mesh on the inlet side, liquid is drawn into the pump.

These pumps excel at moving high viscosity fluids, but have a useful viscosity range of 1cP (centiPoise) to over 1,000,000cP. The single point of end clearance (the distance between the ends of the rotor gear teeth and the head of the pump) is adjustable to accommodate high temperatures, maximize efficiency for high viscosities, and to accommodate for wear.

Compare External Gear Pump VS Internal Gear Pump

Key Components of a Rotary Gear Pump

• Driving Gear: The primary gear connected to the motor shaft that initiates rotation.
• Idler Gear: The secondary gear that meshes with the driver to move the fluid.
• Pump Casing: The outer housing that seals the gears and creates the flow path.
• Shaft and Bearings: Precision components that support high-pressure rotation.
• Seals: Critical for preventing leaks, often involving specialized mechanical seals.

How Does a Rotary Gear Pump Compare to Other Pump Types?

Rotary Gear Pump vs Diaphragm Pump

• Accuracy: Gear pumps provide precise, continuous flow; diaphragm pumps are better for dosing.
• Durability: Gear pumps have simpler mechanics → less maintenance.
• Best Use: Diaphragm pumps for abrasive/corrosive fluids; Gear pumps for oils, syrups, and clean liquids.

Winner: Depends on fluid type, but Rotary Gear Pump dominates for industrial liquids like oil and chemicals.

Rotary Gear Pump vs Peristaltic Pump

• Flow Rate: Gear pumps handle higher flow rates efficiently.
• Efficiency: Peristaltic pumps excel for sterile applications but are less efficient for large-scale operations.
• Maintenance: Gear pumps require less frequent part replacement compared to peristaltic tubing.

Winner: Rotary Gear Pump — ideal for high-volume industrial operations.

Which Industries Use Rotary Gear Pumps?

As a prominent Industrial Pumps Manufacturer in China, LEPU serves diverse sectors that rely on the precision of gear technology.

1. Oil and Petrochemical
Rotary Gear pumps are essential for transferring crude oil, lubricants, and bitumen. Their ability to handle high pressures makes them a staple in refineries alongside the Hot Oil Thermal Transfer Pump and Air-Cooled Pump.

2. Chemical and Fertilizer Plants
Moving aggressive chemicals requires materials like a Centrifugal Process Pump for low viscosity, but rotary gear pumps are used for high-viscosity chemical additives. They ensure precise flow rates for consistent batch processing.

3. Textile and Paper Industries
In textile manufacturing, Rotary gear pumps move dyes and finishing agents. Paper mills often pair them with a Centrifugal Drain Pump or a Two Stage Liquid Ring Vacuum Pump to manage different stages of the production line.

4. Food, Sugar, and Agro-Industries
The sugar and agro-industries use gear pumps to move molasses and syrups. For viscous fluids containing solids, a Progressive Cavity Screw Pump or Slurry Pump may be used as alternatives.

How to Select the Right Rotary Gear Pump?

Selection is based on the fluid’s “Duty Point,” which involves calculating flow rate, viscosity, and system resistance.

1. Viscosity Rating: High-viscosity fluids require slower rotational speeds to prevent cavitation.

2. Pressure Requirements: For extreme pressure needs (up to 50 bar), a Multi-Purpose Rotary Gear Pump is highly effective. For testing these systems, a Motorized Hydraulic Test Pump is often used.

3. Material Compatibility: Ensure the pump casing and gears are compatible with the fluid to prevent wear. Corrosive fluids may require a Polypropylene Corrosion Resistant Centrifugal Pump if viscosity is low.

4. Flow Control: If precise dosing is required, consider a Metering Plunger Pump or a Metering Dosing System Plunger Diaphragm Pump.

Why Choose LEPU As Gear Pump Partner For Your Project

As an Industrial Pumps Manufacturer in China, LEPU founder’s 26+ years of expertise to provide OEM/ODM gear pump solutions tailored for the chemical, oil, and textile sectors. Our strategic location in Huangpu District, Guangzhou, China ensures clients receive superior engineering, prompt service, and rapid access to a comprehensive range of Pump Spare Parts.

• Experience: LEPU SEAL states it was established in 1998 with 26+ years gear pumps OEM/ODM experience.
• Certifications: ISO, SGS, patents/utility models.
• Customers: 200–1,000+ clients; 150+ long-term partners; multi-year relationships (6–15 yrs cited).
• Workforce & capacity: ~100+ skilled workers, ~20 engineers, multiple production lines/CNC.

If you're interested in learning more about our Rotary Gear Pumps or are thinking about making a purchase, don't hesitate to reach out. We're here to help you find the right pump for your specific needs. Let's have a chat and see how we can make your fluid - handling processes more efficient.

Request a custom gear pump design quote for your industrial application — get started at CONTACT US page.

FAQs

1. What is the maximum pressure a  gear pump can handle?

Our Rotary Gear Pump can typically handle pressures up to 50 bar depending on the model and viscosity.

2. Can rotary gear pumps run dry?

No, rotary gear pumps should not run dry as the fluid provides necessary lubrication for the gears; running dry can cause rapid wear.

3. What is the difference between a rotary gear pump and a Centrifugal End Suction Pump?

A rotary gear pump is positive displacement (fixed volume), while a Centrifugal End Suction Pump uses an impeller to create flow based on velocity.

4. Are rotary gear pumps suitable for abrasive fluids?

Rotary gear pumps are best for clean, viscous fluids; for abrasive slurries, Slurry Pump is recommended.

5. How do I maintain my rotary gear pump?

Regularly check gear tooth wear, ensure seal integrity, and use a Motorized Hydraulic Test Pump for periodic pressure verification.

6. Can I use a rotary gear pump for water?

While possible, rotary gear pumps are inefficient for low-viscosity water; a Centrifugal Monoblock Pump or Vertical Inline Centrifugal Pump is usually preferred.

7. Do you provide rotary gear pump spare parts?

Yes, we provide a complete range of Pump Spares for gear pumps, centrifugal pumps, and vacuum systems to ensure minimal downtime.