1、 Basic classification and scope of applicable standards

As an important category of centrifugal blowers, multi-stage centrifugal blowers are subject to basic national standards covering product definition, classification, and general technical requirements. According to GB 28381-2012 "Energy Efficiency Limits and Energy Efficiency Evaluation Values for Centrifugal Blowers", centrifugal blowers can be classified into multi-stage low-speed, multi-stage high-speed, and other categories based on their stage, structure, and speed. Multistage centrifugal blowers are explicitly included in the scope of application of this standard, covering relevant equipment powered by 50Hz three-phase AC power supply and wind pressure ranging from 0.1-0.5kgf/cm 2. At the same time, JB/T 7258-2025 "Centrifugal Blowers", as the core industry standard, specifies the basic requirements for the design, manufacturing, and quality of centrifugal blowers, and is an important basis for the production and inspection of multi-stage centrifugal blowers. This standard is under the jurisdiction of the National Fan Standardization Technical Committee and will be officially implemented on November 1, 2025, replacing the previous JB/T 7258-2006 version.

2、 Energy efficiency limits and grade requirements

In terms of energy efficiency, multi-stage centrifugal blowers must strictly comply with the provisions of GB 28381-2012, which specifies energy efficiency limits, energy-saving evaluation values, and testing methods. Among them, the energy efficiency limit value is measured based on the highest variable efficiency within the range of equipment use, requiring the variable efficiency of multi-stage centrifugal blowers to reach the corresponding specified value. The first level energy efficiency must exceed 82%, and the third level energy efficiency must not be less than 75%, ensuring that the equipment reaches the basic energy-saving level in energy utilization. In addition, the standard also specifies the minimum guaranteed value for the variable efficiency of energy-saving centrifugal blowers, providing clear indicators for the research and promotion of high-efficiency equipment, and assisting in energy conservation and consumption reduction in the industrial field.

3、 Technical parameters and manufacturing specifications

The technical parameters of multi-stage centrifugal blowers need to meet the clear requirements in relevant standards. The flow range is usually 15~500m 3/min, and some high-pressure models can reach 250m 3/min or more. The outlet pressure covers 10-100kPa (gauge pressure), and some models can increase the pressure by 0.2MPa (absolute pressure 1.5kg/cm 2). The motor power ranges from 7.5kW to 200kW, and the speed is mostly 2000-5000rpm. High speed models require professional dynamic balancing design. In the manufacturing process, the rotor, as the core component, consists of multiple impellers, main shafts, spacers, and balance disks. The main shaft is usually made of high-quality carbon steel or high-strength alloy steel, while the impeller can be made of ordinary low-alloy steel or high-strength aluminum alloy through gravity casting and other methods. Each stage of the impeller needs to be designed according to the high-efficiency blower theory, and the outlet is a backward type. The blade passage often adopts advanced quasi three dimensional (three element flow) design to optimize the flow field and improve efficiency. At the same time, the rotor needs to undergo strict static and dynamic balance calibration. The balance quality level of each impeller and the entire rotor component is usually required to be higher than the G2.5 national standard, and some high standards require reaching G1.0 level to ensure that the mechanical vibration value during equipment operation is much lower than the national standard (such as ≤ 4.0mm/s).

4、 Model designation and environmental requirements

In terms of model designation, multi-stage centrifugal blowers must follow JB1418-74 "Rules for the designation of product names and models for centrifugal, axial, rotary ventilation fans, blowers, and compressors". This standard specifies the method for representing blower models, distinguishing key parameters such as rotor structure type, inlet flow rate, and outlet pressure through codes, facilitating product identification and selection. In terms of environmental protection, although HJ/T 251-2006 "Technical Requirements for Environmental Protection Products - Roots Blowers" mainly focuses on Roots blowers, the requirements of low noise and low leakage also provide reference for the environmental design of multi-stage centrifugal blowers. Some enterprises implement the D series multi-stage centrifugal blower technical specifications, which explicitly require the operating noise to be ≤ 85dB (A), and some models can be reduced to below 70dB through mufflers. At the same time, labyrinth seals are used to prevent gas leakage, meeting the needs of environmental protection and safety production.

5、 Testing and Acceptance Standards

The testing and acceptance of multi-stage centrifugal blowers shall be carried out in accordance with relevant standards. The impeller shall undergo overspeed testing during the manufacturing process to ensure its mechanical performance and stability under extreme working conditions. The energy efficiency test is conducted according to the test method specified in GB 28381-2012. By measuring the variable efficiency and other indicators of the equipment, it is determined whether it meets the energy efficiency limit value or energy-saving evaluation value. In addition, in specific application fields such as sewage treatment, single-stage high-speed aeration centrifugal blowers need to meet the technical parameters and inspection requirements in HJ/T 278-2006 standard, which also provides a reference for the application of multi-stage centrifugal blowers in similar fields. (AI generated)