GB/T 40344.1-2021 Active National standards

GB/T 40344.1-2021 Vacuum technology—Standard methods for measuring vacuum-pump performance—Part 1:General description

Publish Date: 2021-08-20 Implement Date: 2022-03-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

Basic Information

Standard Code: GB/T 40344.1-2021

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: Vacuum technology and equipment

ICS Name: Vacuum technology

Publish Date: 2021-08-20

Implement Date: 2022-03-01

Pages: 26 pages

Scope

This part of GB/T 40344 specifies three methods for measuring volumetric flow rate, and separately prescribes methods for measuring the base pressure of vacuum pumps, compression ratios, and critical upstream pressures. The first method for measuring volumetric flow rate (flow rate method) is a basic method: injecting a stable flow of gas into the vacuum pump while measuring the pump's inlet pressure. In actual measurements, the measurement of gas flow rates may be complex or inaccurate. Therefore, two other methods are prescribed to avoid directly measuring flow rates. The second method for measuring volumetric flow rate (small hole method) is suitable for cases where the inlet pressure is very low (high vacuum or ultra-high vacuum) and the flow rate is very small. This method is based on measuring the pressure ratio in the two test chambers of a test hood. The test hood is divided into two chambers by a thin-walled partition with a round hole. The third method for measuring volumetric flow rate (pump-down method) is based on the method of evacuating large containers, which is very suitable for automated measurements. The volumetric flow rate is calculated by measuring the two pressure values before and after pump-down and the volume of the test hood. The measurement results and the final volumetric flow rate are affected by various conditions, such as leakage and venting rates, gas cooling due to near-isentropic expansion during the pump-down interval, and increased flow resistance in the connecting pipeline between the test hood and the vacuum pump under low-pressure molecular flow conditions. The choice of measurement method depends on the attributes of specific types of vacuum pumps. For example, only vacuum pumps requiring upstream pumps need to measure the critical upstream pressure. All measurement parameters for vacuum pumps not specified in this part (such as power consumption measurement) are specified in the corresponding pump standards.