Why can’t a gear pump run dry?

Dry running is an undesirable condition that affects gear pump designs and is characterized by the gear pump operating with insufficient fluid volume. In most pump technologies, this causes cavitation and severe damage to internal pumping components such as impellers, blades, gears, housings, seals and bearings.

Gear pumps have an important limitation in design and operation: they cannot run dry. The following is an analysis of the reasons:

1. Insufficient lubrication
Gear pumps rely on delivered fluid to lubricate internal gears and bearings. Without fluid, friction between gears increases significantly, causing excessive wear and heat. This will not only shorten the service life of the pump, but may also lead to sudden failure of the pump.

2. Poor cooling effect
The liquid in the gear pump not only lubricates, but is also responsible for taking away the heat generated by friction. If a gear pump runs dry and lacks the cooling effect of the liquid, the temperature of the pump body will rise rapidly, which may cause material deformation or damage.

3. Cavitation phenomenon
When running dry, a vacuum will form inside the gear pump, causing air to enter the pump chamber. This causes cavitation, which produces high-frequency vibration and noise, further damaging the pump’s internal structure.

4. Seal failure
Gear pump seals require fluid lubrication and cooling to maintain their performance. Dry running can cause seals to overheat and wear, ultimately leading to leaks and pump failure.

5. Reduced efficiency
Without liquid lubrication and cooling, the mechanical efficiency of a gear pump would be significantly reduced. Increased friction and heat buildup make the pump more difficult to operate, increasing energy consumption and reducing efficiency.

To ensure proper operation and long life of the gear pump, dry running must be avoided. Operators should check the fluid level regularly to ensure that the pump always has an adequate supply of fluid before starting and during operation. In addition, selecting the appropriate liquid type and viscosity is also key to ensuring gear pump performance.