Moving thick liquids through an industrial system can be difficult. Oils, resins, bitumen, polymers, paints, and other viscous fluids need a pump that can maintain steady flow without excessive strain.
This is where internal gear pumps are useful. Their simple gear arrangement allows them to move fluids in a controlled and reliable way. Understanding the internal gear pump working principle helps engineers choose the right pump for their process.
The pump’s construction also affects its performance. The internal gear pump design supports smooth transfer and can handle many fluids across different industries.
This guide explains how internal gear pumps work, their main benefits, common uses, and factors to consider when choosing them. It also looks at how they differ from other positive displacement pump designs.
What Is an Internal Gear Pump?
An internal gear pump is a positive displacement pump that uses two gears to move fluid. One gear is smaller and sits inside a larger gear.
The gears rotate together inside the pump casing. As they move, they create spaces that draw in fluid and carry it towards the outlet.
The basic internal gear pump design includes:
- A larger internal gear
- A smaller idler gear
- Pump casing
- Drive shaft
- Suction and discharge ports
- Shaft and gear support components
The exact construction may vary by model and application. Some designs also include heating or cooling jackets for fluids that need temperature control.
The simple arrangement is one reason internal gear pump manufacturers use this design for demanding fluid transfer duties.
Understanding The Working Principle
The internal gear pump working principle is based on positive displacement. Each rotation moves a fixed volume of fluid through the pump.
The process happens in a few simple stages.
- Fluid Enters the Pump
When the gears rotate, their teeth move away from each other near the suction port. This creates a low-pressure area.
Fluid then enters the pump casing.
- Fluid Gets Trapped
The liquid becomes trapped in the spaces between the gear teeth and the pump casing.
The fluid does not pass through the centre of the gears. Instead, it travels around the outer part of the pump chamber.
- Fluid Moves Towards the Outlet
As the gears continue to rotate, they carry the trapped liquid around the casing.
This creates a steady movement from the suction side to the discharge side.
- Fluid Leaves the Pump
When the gears come back into mesh, the available space becomes smaller. This pushes the fluid towards the discharge port.
This is the core of the internal gear pump working principle. Continuous gear rotation creates consistent fluid displacement.
How The Design Supports Smooth Flow
The internal gear pump design plays an important role in flow quality. The fluid is moved through controlled cavities instead of being pushed in sudden bursts.
This can result in:
- Low pulsation
- Smooth fluid transfer
- Low vibration
- Quiet operation
- Consistent flow
The design can also support self-priming. This is useful when the pump needs to draw fluid from a tank or vessel.
Some internal gear pump manufacturers offer bracket-mounted and gearbox-mounted configurations. The right mounting option depends on the system layout and operating requirements.
Main Advantages Of Internal Gear Pumps
The internal gear pump advantages become especially useful when handling viscous fluids.
One major benefit is their ability to move thick liquids. The design can handle fluids that are difficult to transfer using conventional centrifugal pumps.
Other internal gear pump advantages include:
- Good self-priming performance
- Smooth and steady discharge
- Low noise and vibration
- Compact construction
- Easy access for maintenance
- Suitability for high-viscosity fluids
- Options for different sealing arrangements
The exact performance depends on pump size, fluid properties, speed, pressure, and temperature.
Where Are Internal Gear Pumps Used?
The range of internal gear pump applications is wide. They are used where reliable movement of liquids is important.
Common internal gear pump applications include:
- Oil and lubricant transfer
- Bitumen handling
- Paint and coating production
- Chemical processing
- Polymer processing
- Resin transfer
- Food processing
- Pharmaceutical processing
- Soap and detergent production
The pump can also be configured for fluids that need heating or cooling during transfer.
For example, thick materials may become easier to pump when their temperature is controlled. In such cases, a suitable jacketed pump design can help maintain the required fluid condition.
Choosing The Right Pump for the Fluid
Not every internal gear pump is suitable for every process. Fluid properties should be checked before selection.
Important factors include:
- Viscosity
Thick fluids need a pump designed for high-viscosity service. The expected viscosity range should be shared with the manufacturer.
- Temperature
Fluid temperature affects viscosity and pump component selection. The pump should be rated for the actual operating temperature.
- Pressure
The required discharge pressure must match the pump’s rated capacity. Excess pressure can increase wear and reduce service life.
- Flow Rate
The required flow rate helps determine pump size and operating speed.
- Material Compatibility
Pump materials and seals must be compatible with the fluid. This is especially important when handling chemicals or aggressive liquids.
Experienced internal gear pump manufacturers can use these details to recommend a suitable configuration.
Internal Gear Pumps Vs Other Positive Displacement Pumps
Internal gear pumps are not the only positive displacement option. Different processes may require different pump designs.
For example, high pressure triple screw pumps use three screws to move fluid. They are often selected for applications requiring smooth flow and specific pressure performance.
By comparison, internal gear pumps use an internal and external gear arrangement. Their compact design makes them useful for many viscous fluid transfer applications.
The right choice depends on:
- Required pressure
- Fluid viscosity
- Flow rate
- Temperature
- Installation space
- Maintenance needs
Neither design is suitable for every duty. Process conditions should guide the decision.
Maintenance And Operating Considerations
Proper operation can help maintain pump performance. Before starting the system, operators should confirm that the pump is correctly installed and suitable for the fluid.
Regular checks can include:
- Seal condition
- Bearing condition
- Coupling alignment
- Unusual noise or vibration
- Leakage
- Operating pressure
- Fluid temperature
Following the manufacturer’s maintenance recommendations is also important.
The internal gear pump advantages can be maintained over a longer operating period when the pump is correctly sized, installed, and serviced.
Selecting A Reliable Pump Manufacturer
The manufacturer can have a major impact on pump performance. Experienced internal gear pump manufacturers understand how pump construction changes with fluid and operating conditions.
When evaluating a supplier, businesses should consider:
- Product range
- Technical support
- Material options
- Seal choices
- Application experience
- Maintenance support
- Customisation options
A manufacturer should also be able to explain the internal gear pump working principle and recommend a suitable design based on actual process conditions.
Making Viscous Fluid Transfer More Reliable
The internal gear pump working principle is simple. Two gears rotate together to create controlled spaces that draw in, carry, and discharge fluid. This design makes internal gear pumps useful for many industrial fluid transfer duties.
The internal gear pump advantages include smooth flow, self-priming capability, low pulsation, and suitability for viscous fluids. Their internal gear pump applications range from oils and bitumen to chemicals, polymers, food products, and pharmaceuticals.
While high pressure triple screw pumps may suit certain high-pressure duties, internal gear pumps offer a practical option for many viscous fluid applications.
Delta PD Pumps develops positive displacement pumping solutions for industrial requirements. They provide internal gear pump configurations designed around factors such as flow, pressure, viscosity, temperature, and mounting needs. Their application-focused approach helps businesses select suitable equipment for demanding fluid transfer processes. Businesses can discuss their requirements with Delta PD Pumps and request a quote for the appropriate solution.
