The noise standard system for multi-stage centrifugal blowers covers three dimensions: product factory limits, on-site measurement methods, and compliance requirements for industrial scenarios. Based on your concerns about industrial equipment selection needs, the core content can be divided into the following sections:
📏 Core national standards and industry norms
At present, a complete standard system for noise control of multi-stage centrifugal blowers in China has been formed, with the core basis as follows:
Measurement method standard: GB/T 2888-2008 "Methods for Measuring Noise of Fans and Roots Blowers" specifies the layout of measuring points for A-weighted sound pressure level and environmental correction rules, which is the unified benchmark for all noise detection.
Product limit standard: JB/T 8690-1998 "Noise Limits for Industrial Ventilators" sets the factory noise upper limit for centrifugal blowers of different powers and speeds. The factory noise of conventional models should be controlled within the range of 90-100dB (A), while the optimized design of D-type low-noise models can directly achieve below 85dB (A).
Scenario compliance standard: GB 12348-2008 "Emission Standard for Industrial Enterprise Boundary Environmental Noise" specifies the daytime noise limit of 70dB (A) and the nighttime noise limit of 55dB (A) in industrial areas. The occupational health requirements inside the workshop must comply with GBZ 2.2-2007, and the equivalent noise exposure of operators for 8 hours must be controlled within 85dB (A).
🔍 Noise characteristics and grading criteria
The noise of multi-stage centrifugal blowers is mainly composed of mid to high frequency aerodynamic noise, with a small amount of mechanical vibration noise added. The noise standards of different technical routes vary significantly:
|Model type | Typical operating noise value | Core noise reduction characteristics|
|Ordinary traditional models | 90-100dB (A) | No special noise reduction design, requiring a complete noise reduction system|
|Conventional optimized models | ≤ 85dB (A) | Factory standard basic muffler, meeting the requirements of basic industrial scenarios|
|Maglev/Air Suspension Model | 65-75dB (A) | Contactless bearings with no mechanical friction, equipped with a flow guide and sound insulation cover, no need for additional complex noise reduction|
The propagation characteristics of this type of mid to high frequency noise are clear, and effective isolation can be achieved through conventional sound insulation materials. It is easier to control and meet the standards for low-frequency impact noise from Roots fans.
⚙️ Technical requirements for supporting noise control
The standard system contains mandatory noise reduction requirements for equipment design and on-site installation, with core points including:
Source optimization requirements: The impeller must undergo strict static and dynamic balance correction, with bearing amplitude ≤ 0.04mm. Through streamlined impeller design and reasonable control of blade tip clearance, the generation of aerodynamic noise can be reduced from the source.
Supporting noise reduction configuration: The inlet and outlet of the equipment must be matched with impedance composite mufflers, which can cover high, medium, and full frequency band noise in a targeted manner. The noise reduction efficiency can reach 30-60 decibels without affecting ventilation efficiency.
On site installation specifications: Industrial spring shock absorbers must be installed on the base, and flexible soft connections should be used at the inlet and outlet to block the transmission of low-frequency vibrations to the building structure and avoid secondary noise pollution caused by vibration amplification.
Sound insulation requirements for the computer room: The independent fan room should adopt a sound insulation and sealed design, with soundproof louvers installed on the ventilation openings to ensure that the noise outside the computer room is directly reduced to within 70dB (A), meeting the environmental protection standards of the factory.
⚠️ Common misconceptions about standard implementation
Many projects only focus on the factory noise level of equipment, ignoring the standard adaptation of on-site working conditions, which can easily lead to acceptance failure:
It is not enough to only refer to the noise value on the equipment nameplate. It must be retested according to the GB/T 2888 standard under actual operating conditions to avoid the nameplate data being the ideal value under laboratory idle state.
It is not enough to rely solely on a single muffler for noise reduction. A combined solution of shock absorption and machine room sound insulation must be implemented simultaneously. Otherwise, low-frequency vibration noise will be transmitted outward through the wall and still cannot pass the factory's environmental protection testing.
When selecting, priority should be given to models with built-in three-way flow impellers and low-noise reflux designs to reduce the noise base from the source, which is more than 40% lower than the comprehensive cost of passive noise reduction in the later stage.
