Internal gear pump is a most famous type of the gear pump. Internal gear pumps move fluid by repeatedly closing a fixed volume to adjacent gears and mechanically moving the fluid to produce a fluent, pulse-free flow comparative to the speed of the gear. This pump most commonly uses for slim fluids like fuel oils and solvents but is also suitable for viscous liquids like adhesives, chocolate, and asphalt. In addition to the wide range of viscosities, the pump also has a wide range of temperature control capabilities. This is achievable because clearance point. The space can be adjusted to accommodate high temperatures and maximize the handling efficiency of high viscosity fluids.

The internal gear pump is automatic, without pulsation, and can remain stationary even for a short time. They also rotate in both directions, which means that a pump can be used to load and unload vessels. Since the internal gear pump has only two moving parts, it is reliable, easy to use, and easy to maintain.

How does the internal gear pump work?

The work cycle of the internal gear pump is divided into three phases: filling, transport, and delivery.

1. When the gears are detached near the pump inlet, they create a larger volume. As the gear continues to rotate in front of the pump housing and diaphragm, fluid flows into the cavity and is trapped by the gear teeth.

2. Stuck fluid moves into the casing from the suction to the exhaust outlet.

3. As the gear teeth are stuck on the discharge side of the pump, their volume is reduced and liquid is poured under pressure.

The tight tolerance between the gear and the casing allows the pump to create suction at the inlet and prevent liquid from escaping from the discharge side (although the possibility of low viscosity liquid leakage is greater).

Main features and advantages of the internal gear pump 

The internal gear pump has a very simple operating principle. It has a limited number of moving parts. They may not match the pressure generated by the feedback pump or the flow rate of the centrifugal pump, but they may offer higher pressures and performance than lob pumps or vane pumps. Internal gear pumps have better suction capacity than external gear pumps and are more suitable for high viscosity fluids. Since the output is proportional to the speed, internal gear pumps are usually used for metering and mixing operations. The low internal volume provides a reliable measurement of the fluid passing through the pump and provides precise flow control.

What are the main applications of an internal gear pump?

They are commonly used for diluted liquids such as water, solvents, and baking oils, but are ideal for pumping concentrated liquids such as asphalt, chocolate, and binders. Internal gear pumps also have a wide operating temperature range which makes them suitable for pumping hard liquids such as tar and molten Sulphur.

Some common applications of internal gear pumps are:

• Fuel oil and lube oil
• Resins and polymers
• Alcohols and solvents
• Asphalt, bitumen, and tar
• Polyurethane foam (Isocyanate and polyol)
• Food products such as corn syrup, chocolate, and peanut butter
• Paint, inks, and pigments
• Soaps and surfactants
• Glycol

Limitations of the internal gear pump

Internal gear pumps are unable to move large solids. Due to their low tolerance, large solids can easily damage the pump. They can tolerate some small solids suspended in abrasive liquids, but be aware that this can damage the pump and cause it to lose performance.

As the viscosity of the fluid decreases, the efficiency of the internal gear pump decreases.

In the case of a product with low viscosity and high delivery pressure, the product “slips” into the processing space of the pump and allows it to circulate again from the discharge to the suction.

In most cases, product slippage is an efficiency issue, but it can cause some products to harden into a fixed state, such as chocolate and glue, which are more irritating.