The temperature rise of the Roots vacuum pump refers to the difference between the highest temperature measured on the surface of the entire pump and the room temperature under the condition of stable operation of the ultimate vacuum or rated vacuum (referring to the direct exhaust atmospheric Roots vacuum pump). The type of thermometer used to measure temperature rise is not limited, but should have a measurement accuracy of ±1°C. When marking the temperature rise, the room temperature at that time and the cooling conditions of the pump, including the cooling method, should be marked at the same time.

The outlet pressure of the Roots vacuum pump refers to the pressure of the jacket near the exhaust port corresponding to a certain inlet pressure value under the condition of stable operation of the Roots vacuum pump. The test of the outlet pressure can be carried out simultaneously with the determination of the pumping rate, starting from an appropriate value near the ultimate vacuum, until about the allowable inlet pressure of the pump. The outlet pressure is determined for each inlet pressure value.

The measurement position of the outlet pressure is specified in the ministerial standard. The distance between the pressure measuring tube and the pump outlet flange should not be greater than the outlet diameter of the pump, and the opening plane of the pressure measuring tube should be parallel to the airflow direction. The insertion depth is 1/4d, but not more than 50mm.