Gear Pump Selection Guide

A gear pump is a type of positive displacement pump that uses rotating gears to move fluid through the pump. The main features of a gear pump include:

• High volumetric efficiency: Gear pumps can move a large amount of fluid with relatively small amounts of input power.
• Constant flow: Gear pumps can maintain a constant flow rate regardless of changes in the system's pressure or the pump's speed.
• Low pulsation: Gear pumps produce low levels of pulsation, which makes them well-suited for applications where smooth flow is important.
• Low noise level: Gear pumps generate low noise, compared to other displacement pumps, such as peristaltic pumps. 

Gear Pump Applications

Gear pumps are commonly used in medical applications due to their ability to handle viscous fluids, precise flow control, and high-pressure capabilities. Some examples of how gear pumps are used in medical applications include:

• Drug delivery systems: Gear pumps are used in drug delivery systems to precisely control the flow of medication. This can include pumps for intravenous drug delivery, pumps for insulin delivery, and pumps for chemotherapeutic drugs.
• Blood pumps: Gear pumps are used in artificial heart and blood pump systems to circulate blood through the body. This includes both heart-assist devices and total artificial heart systems.
• Dialysis machines: Gear pumps are used in dialysis machines to circulate blood and dialysis solution through the machine. This allows for precise control of the flow rate and pressure of the fluid being pumped.
• Laboratory equipment: Gear pumps are used to transfer fluids between different components of laboratory equipment, such as centrifuges and chromatography columns.
• Medical equipment: Gear pumps are used in various medical equipment such as surgical instruments, medical devices, and equipment for diagnostics and therapy.

Gear Pump Selection Guideline

The working principle of a gear pump is based on the positive displacement principle, where the fluid is moved by the meshing of two gears. The gears are typically made of hardened steel and are in a housing that is sealed to prevent leakage.

The gears are arranged in such a way that they rotate in opposite directions and mesh together, creating a sealed chamber between them. As the gears rotate, they trap a fixed volume of fluid between them and move it through the pump. The fluid is then forced out of the pump through the outlet port.

Gear pumps are classified into several types based on their design and application. Some of the most common types of gear pumps include:

• External gear pumps: External gear pumps have gears that are located outside of the pump housing. They are commonly used for low viscosity fluids and are available in single and double configurations.
• Internal gear pumps: Internal gear pumps have gears that are located inside the pump housing. They are commonly used for high viscosity fluids and are available in single and double configurations.
• Spur gear pumps: Spur gear pumps have gears that are cut in a spur gear design. They are commonly used for low to medium viscosity fluids and are available in single and double configurations.
• Helical gear pumps: Helical gear pumps have gears that are cut in a helical gear design. They are commonly used for high viscosity fluids and are available in single and double configurations.
• Herringbone gear pumps: Herringbone gear pumps have gears that are cut in a herringbone gear design. They are commonly used for high viscosity fluids and are available in single and double configurations.
• Worm gear pumps: Worm gear pumps have a worm gear design, which is typically used for high viscosity fluids and low flow rates.
• Screw pumps: Screw pumps have a gear design that is typically used for high viscosity fluids, low flow rates, and high-pressure applications.

It's important to note that the above classifications are general and that within each category, there are different variations and designs, which are tailored to specific applications.

When selecting a gear pump, the following guidelines should be considered:

• Required flow rate: The flow rate required for the application will determine the size and type of gear pump needed.
• Viscosity of fluid: The viscosity of the fluid being pumped will determine the type of gear pump needed. For example, a high viscosity fluid will require a gear pump with a larger gear size and a lower speed.
• Pressure requirements: The pressure required for the application will determine the type of gear pump needed. For example, a high-pressure application will require a gear pump with a higher-pressure rating.
• Compatibility with materials: The gear pump should be compatible with the materials used in the application, such as the fluid being pumped, and any seals or gaskets used. Usually, the internal gears are made of stainless steel, PEEK, PTFE etc. It's also important to ensure that the gear pump is compatible with the materials used in the application, such as the fluid being pumped, and any seals or gaskets used.
• Fluid temperature requirement: The gear pump should work under the rated temperature limit. Too high liquid temperature may damage the pump and internal gears. 
• Cleanliness requirements: The gear pump should meet any cleanliness requirements for the application, such as being able to operate in a sterile environment.
• Life cycle cost: The gear pump should have a reasonable life cycle cost, taking into account factors such as initial cost, energy consumption, and maintenance costs.
• Noise level: The noise level of the gear pump should meet the requirements of the application, particularly if the gear pump will be installed in a noise-sensitive environment.
• Power supply: The gear pump should be compatible with the available power supply and should meet the voltage, amperage, and frequency requirements.
• Reliability and maintenance: The gear pump should have a good record of reliability and ease of maintenance.
• Quality of Manufacturers: It's always recommended to go for a reputable and well-established manufacturer with a proven track record of producing quality gear pumps.

Can Gear Pump Dry Run?

Gear pumps can be damaged if they are operated without fluid, also known as dry run. When the gears rotate without fluid, they can generate excessive heat and wear on the gears and bearings, leading to damage or failure of the pump.

To avoid dry run, the following precautions can be taken:

• Use a level switch: A low level switch can be installed in the fluid tank to detect when the fluid level is too low. This will automatically shut off the pump to prevent dry run.
• Use a pressure transducer:  A pressure transducer can be installed in the pump system to detect when the pump is not producing enough pressure. This will automatically shut off the pump to prevent dry run.
• Use a flow sensor: A flow switch can be installed in the pump system to detect when the flow rate is too low. This will automatically shut off the pump to prevent dry run.
• Visual Inspection: Regularly inspecting the fluid level and ensuring that the fluid level is above the minimum level required.
• Use a priming pump: A priming pump can be used to fill the gear pump with fluid before it is started. This can be done manually or automatically.
• Use a buffer tank: A buffer tank can be installed in the pump system to provide a reserve of fluid. This can help to prevent dry run by maintaining a minimum fluid level in the gear pump.
• Proper Maintenance: Regularly maintaining the gear pump including changing the oil, inspecting the seals and gaskets for leaks, and checking the gear and bearing for wear.
• It's important to note that gear pumps should not be operated without fluid for any period of time, and if any of the above precautions fail, it's important to shut the pump off immediately to prevent damage.

Can Gear Pump Handle Fluids with Particles? 

Gear pumps can handle particles in fluid to some extent, but it depends on the size and abrasiveness of the particles, as well as the design of the gear pump. Generally, gear pumps are not recommended for pumping fluids that contain large or abrasive particles, as they can cause damage to the gears and bearings.

If the gear pump is designed to handle particles, it will typically have a larger gear size and a lower speed to accommodate the particles. The gears and housing may also be made of harder materials to resist wear and damage caused by the particles.  However, if the particles are too big or abrasive, they can cause damage to the gears and bearings, leading to reduced efficiency, leakage, and ultimately failure of the pump.

To avoid damage from particles, the following precautions can be taken:

• Use a filter: A filter can be installed in the pump system to remove particles from the fluid before it enters the gear pump.
• Use a strainer: A strainer can be installed in the inlet of the gear pump to remove larger particles.
• Use a centrifugal pump: A centrifugal pump can be used to pump fluid containing particles, as the impeller can handle larger particles without causing damage.
• Use a positive displacement pump: Positive displacement pumps such as diaphragm or peristaltic pumps can handle particles in fluid better than gear pumps, as they don't have gears that can be damaged by particles. These pumps use a combination of pressure and a squeezing action to move the liquid and any suspended solids through the pump. The pumping mechanism helps to minimize damage to delicate particles, such as red blood cells, in the fluid being pumped.
• Proper Maintenance: Regularly maintaining the gear pump, inspecting the gears and bearings for wear, and replacing worn parts as necessary.

It's important to note that the fluid should be filtered and cleaned before entering the gear pump to avoid damage and to keep the pump efficiency high. Also, it's important to use the right type of gear pump for the fluid and particles that will be pumped.

Micro Gear Pumps

WT3000 series micro gear pumps we offered are specially designed for batch dispensing and filling applications. The pump has LCD that can display the parameters and running states. The flow rate control mode is for continuous fluid transferring ranging from 85.7 mL/min to 2571.4 mL/min, while the dispensing control mode is for dispensing the fluid at desired dispensing volume (0.1mL to 999 L).  The pump speed can be adjusted manually through the control panel or automatically through external control signal.  Different gear materials (PEEK or PTFE etc.) are available to ensure pump chemical compatibility. The outlet pressure changes along with the change of setting flow rate. The maximum pressure can be reached about 1.4MPa.   The main features are as follows: 

• The maximum pressure up to 1.4MPa (203PSI)
• Large flow range of 85.7 to 2571.4ml/min (max speed of 3000 RPM)
• Brushless DC motor with offers ±1.0% speed control accuracy with a 10 to 1 turndown ratio. 
• Stainless steel pump head and PEEK/PTFE gear materials 
• Flow rate function: Deliver the liquid according to the set flow rates.
• Dispensing function: Dispensing volume, copy number and pause time can be set.
• Calibration function: The flow rates and the dispensing volume can be calibrated. 
• Prime function for fast filling and emptying.
• External control input: Control the flow rates and start/stop of the pump by can manually controlled or through external control signal:  4-20mA, 0-5V, 0-10V, 0-10kHz signal or communication command (RS485) 
• External control output: Output start/stop and speed signal.
• Foot switch:  Control the start/stop of the pump.
• Memory function: Store the running parameters automatically.
• Cooling mode: Heat-dissipation fan 
• Running directions: Clockwise
• The non-contact magnetic coupling driver prevents the liquid from contacting the driver (corrosive media transfer is possible)
• Only the gears and sealing O-rings are consumables (minimum maintenance required)  

If you have any questions or need assistance to select a micro gear pump for your applications, please feel free to reach out to us a sales at auroraprosci dot com!