How to distinguish the sound power level and sound pressure level of air conditioning box?

The sound power level describes the source characteristics of the sound energy radiated outward by the equipment, and the sound pressure level describes the intensity of the sound received by a certain measuring point. Both may be expressed in dB, but they cannot be directly subtracted or interchanged. When comparing air-conditioning box noise, you should first confirm the index name, frequency weighting and test boundaries.

Why do the same device measure different sound pressures?

Measuring point distance, room sound absorption, wall reflection and background noise will affect the sound pressure results; the relative positions of the air duct, computer room and equipment will also change the on-site performance. Sound power helps to compare sound sources in acoustic design, but the operating conditions of the unit and the measurement method still need to be specified, and the same value cannot be assumed to be maintained under any conditions.

Sound travels from the device to the target area through several paths, including air ducts, box radiation and structural vibration. Different paths require different treatment measures, please refer toWhat noise propagation paths should we pay attention to when selecting an air-conditioning box? . If the project has noise targets in the machine room or work area, the equipment sound source data and propagation paths should be checked together.

What questions do the two indicators answer?

The sound power level does not change with the distance of the measuring point, and is suitable for comparing the sound source itself between different solutions; the sound pressure level corresponds to the specific location, which is closer to the on-site experience, but is greatly affected by the environment. It is a common misuse to regard the sound power level as the actual sound pressure at a certain location, or to regard the sound pressure level at a certain measuring point as an inherent property of the equipment. Sub-band data is particularly important for noise reduction design. Looking only at the total A-weighted value may mask low-frequency components. How to write the test conditions of noise data, please refer toWhat test conditions need to be stated for air conditioning box noise data?。

How to prevent mixed use of indicators in procurement documents

It becomes clear what acoustic data the device provides and what the project requires to achieve at which location. If the room has strict noise requirements, acoustic or system design should be combined with propagation path calculation measures. A dB value in an equipment sample cannot alone be used as a guarantee of sound pressure in a computer room or work area.

When inquiring, you can ask the supplier to explain whether the data source is measurement, calculation or selection software, and indicate the air volume, pressure, speed and accessory configuration. Sound pressure values ​​at different distances or results under different air volumes cannot be judged by simply arranging numbers. If on-site verification is required, the location of the measuring points, background noise correction and environmental conditions should be agreed upon in advance.

How to use these two types of data in the selection stage

When selecting a model, first use the sound power level to compare the sound source levels of different fan and cabinet solutions, and then estimate the sound pressure at the target location based on the layout of the computer room. If the equipment is close to the target area, or the air duct path is short and has few bends, the sound pressure level may more directly reflect the problem; if it is necessary to compare the impact of multiple solutions on the remote area, the sound power level is more valuable as a reference. Using the two together is more reliable than just looking at one number.

Fan form, speed and box structure will all affect noise performance, please refer toHow do the backward-inclined and forward-inclined fans compare when used in air conditioning boxes? andWhat are the differences between double-layer box boards and single-layer box boards used in air-conditioning boxes? . When the fan operating point deviates from the high efficiency area, the noise may also increase. Please refer toWhy should we check the efficiency range when selecting air-conditioning box fans?。

Aili industrial supporting equipment

When checking the noise data with Aili Industrial, please also indicate the target measurement points and operating conditions to facilitate the differentiation of equipment data and on-site acoustic requirements. Aili Industrial can jointly check the fan, motor, box structure and control configuration, and provide equipment-side acoustic data under corresponding working conditions during the selection stage; the manufacturing end covers independent research and development and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. The fan working point and box structure can be confirmed in the same package.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andCheck the fan filter unit at the EFU equipment end ; if gaseous pollutants need to be controlled, please communicate separately.Chemical filter solutions. The specific acoustic performance, applicable environment and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. Actual results are subject to on-site leak detection and performance test results.

Submit project parameters:https://ailigy.com/contactus.html

Related questions and answers

Can sound power level and sound pressure level be directly subtracted?
cannot. The two dimensions have different meanings. The sound power level describes the sound source, and the sound pressure level corresponds to the specific measuring point and cannot be directly subtracted or interchanged.

Can the dB value on the sample be used as a guarantee for the noise in the computer room?
Cannot stand alone as a guarantee. Sample values ​​may correspond to specific operating conditions and measurement methods, and computer room noise is also affected by propagation paths, room acoustics, and background noise.

What noise information can Aili Industrial provide?
Acoustic data on the equipment side can be provided based on the operating conditions, and the measurement points and methods can be explained; specific indicators need to be confirmed according to the project agreement and on-site conditions.

Related articles

1. What noise propagation paths should we pay attention to when selecting an air-conditioning box?

2. What test conditions need to be stated for air conditioning box noise data?

3. How do the backward-inclined and forward-inclined fans compare when used in air conditioning boxes?

4. What are the differences between double-layer box boards and single-layer box boards used in air-conditioning boxes?

Key points for selection and acceptance inspection