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.
One of our customers from Latin America once tested some small rotary vane vacuum pump samples and hesitated to continue the testing because an operating temperature of 120°C was detected on the pump body. He wondered if the pumps could continue the operation for hours.
Normally the temperature can be 60°C on the surface of a big-sized vacuum pump. For small vacuum pumps however, the operating temperature is much higher, namely 90 – 110°C at 50 Hz and 110 – 130°C at 60 Hz.
The reasons for the high operating temperature and big differences between different models are as follows:
- Ambient temperature
Normally the ambient temperature is the room temperature around 25°C. In some areas or in some seasons, the room temperature is extraordinary high. Consequently, the working temperature becomes higher than normal level.
- Pump structure
A small-sized rotary vane vacuum pump, for example ASV-20, has compact structure without any extra fan besides the one inside the motor. Bigger pumps however, have 2 fans installed to reduce the working temperature efficiently.
- Vacuum oil
Besides the oil quality, the viscosity of the vacuum oil also plays a role on the temperature. The higher the viscosity of the vacuum oil used, the more it is for the heat of the pump to be carried away by the oil. For example, the recommended viscosity index for ASV-20 is 46. The heat generated by the pump will be higher if oil with viscosity of 100 is supplied.
- Motor speed
The motor speed has a significant and decisive influence on the pump temperature. It’s understandable that slow speed generates low heat. A big pump is usually equipped with a 4-pole motor with 1440 rpm @50 Hz while a small pump works with a 2-pole motor with 2880 rpm @50 Hz. The temperature is even higher when the motor operates at 60 Hz.
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