Classification of static pressure box:

1. Resistive muffler: It is a type of sound-absorbing material attached to the box to absorb sound energy and reduce noise. It is generally used to eliminate high and medium frequency noise. However, due to structural reasons, it is not suitable for high temperature, high humidity, and high speed conditions.

2. Anti type muffler: It is designed to reduce noise by modifying the cross-section. The commonly used soundproof static pressure box is based on this principle. Generally, there are no specific requirements for wind systems to reduce mid to low frequency noise.

3. Impedance composite: Of course, it combines the structural principles of both. Can eliminate low, medium, and high frequency noise. But the requirements for the wind system are the same as those for resistive mufflers. For general civil air conditioning ventilation systems, I personally think it is better to choose impedance composite mufflers. The resistive muffler has outstanding mid to high frequency noise reduction function. According to the different shapes of the airflow channel, it can be divided into straight pipe type, sheet type, folded plate type, maze type, honeycomb type, acoustic flow type, baffle type, elbow type, etc. Resistance mufflers are suitable for eliminating mid to low frequency noise or narrowband noise. According to their different operating principles, they can be divided into various types such as expansion type, resonant cavity type, and dry type. Impedance composite muffler includes acoustic filtering equipment such as resonant cavity, expansion chamber, perforated screen, etc. It summarizes the outstanding mid to high frequency noise reduction characteristics of impedance muffler and the good low-frequency noise reduction characteristics of impedance muffler. Therefore, its noise reduction frequency bandwidth is one of the most commonly used standardized muffler series. Suitable for wind speeds of 6-8 meters per second, with a maximum of 8-12 meters, it can be used independently or in series. Noise reduction effect: Low frequency of 10-15 dB/m, medium frequency of 15-25 dB/m, high frequency of 25-30 dB/m, with an average drag coefficient of 0.4. According to "Air Conditioning", soundproof elbows and soundproof static pressure boxes are both types of mufflers. A muffler is a device that allows airflow to pass through while effectively obstructing or weakening the propagation of sound energy outward.