Normal operating temperature of a vacuum pump

operating temperature of a vacuum pump

This article tries to explain what's the normal operating temperature of a vacuum pump and why there're differences between small and big pumps.

During a testing phase, one of our customers from Latin America had reservations about continuing with the evaluation of our small rotary vane vacuum pump  samples. This hesitation arose when they detected an operating temperature of 120°C on the pump body. The customer expressed concerns regarding the pumps’ ability to sustain continuous operation for extended periods of time.

Typically, the surface temperature of a large-sized vacuum pump would be around 60°C. For small vacuum pumps however, the operating temperature tends to be higher. Specifically, at 50 Hz, it ranges from 90°C to 110°C, while at 60 Hz, it can reach 110°C to 130°C.

There are several reasons behind the high operating temperature and significant variations between different models of vacuum pumps. These factors include:

  • Ambient temperature

Under normal conditions, the ambient temperature typically corresponds to the room temperature, which is around 25°C. However, in certain areas or during specific seasons, the room temperature can be exceptionally high. As a result, the operating temperature of vacuum pumps can exceed the normal levels due to the elevated ambient temperature.

  • Pump structure

In contrast to larger pumps, a small-sized rotary vane vacuum pump like the ASV-20 typically features a compact structure without any additional fans apart from the one integrated within the motor. On the other hand, larger pumps often incorporate two fans to enhance efficient cooling and effectively reduce the operating temperature. The presence of multiple fans in bigger pumps aids in better heat dissipation, enabling them to maintain lower working temperatures during operation.

  • Vacuum oil

In addition to oil quality, the viscosity of the vacuum oil used also influences the operating temperature of the pump. Higher viscosity in the vacuum oil makes it more difficult for the heat generated by the pump to be carried away effectively. For instance, in the case of ASV-20, a recommended viscosity index of 46 is advised. If oil with a viscosity of 100 is used instead, the heat generated by the pump is likely to be higher due to the reduced efficiency of heat dissipation provided by the thicker oil. Therefore, adhering to the recommended viscosity index helps to ensure optimal heat transfer and temperature control within the pump.

  • Motor speed

The motor speed of a vacuum pump has a substantial impact on its operating temperature. It is logical to understand that lower motor speeds result in lower heat generation. In general, larger pumps are equipped with 4-pole motors that operate at 1440 rpm @50 Hz, while smaller pumps utilize 2-pole motors that run at 2880 rpm @50 Hz. When the motor operates at 60 Hz, the temperature tends to be even higher due to the increased speed. The higher rotational speed of the motor in smaller pumps contributes to higher heat production, leading to elevated operating temperatures.

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