Are the standards for air velocity and air volume of box-type filters the same in different industries?

The air velocity and air volume standards of box-type filters vary by industry, which is determined by the core demands of different industries, such as cleanliness requirements, pollutant characteristics, and system functions (such as ventilation, dust removal, and purification). Even for the same type of box filters (such as medium-efficiency or high-efficiency ones), there may be significant differences in design air velocity and air volume in different industries. The following is the specific analysis:
I. Core Difference: Industry demand determines the "air volume-air velocity" design logic
Different industries have different filtration goals (such as controlling microorganisms, dust, chemical particles, etc.), which leads to completely different requirements for "air volume processed per unit time" (to ensure the ventilation efficiency of the clean area) and "air flow velocity" (to ensure filtration efficiency and stability)
For industries with extremely high cleanliness requirements (such as semiconductors and pharmaceuticals), Priority should be given to ensuring filtration efficiency. The air velocity must be strictly limited (to prevent small particles from penetrating), and at the same time, high air volume should be used to meet the air change rate.
In the industrial dust removal/coarse filtration industry (such as welding and building materials), priority should be given to ensuring processing capacity (rapid dust removal with large air volume), and higher air speeds are allowed (as the main filtration is for large particles, high air speeds are conducive to capture).
General ventilation industry (such as office buildings and shopping malls): Balance efficiency, energy consumption, and comfort, with wind speed and air volume in the middle range.
Ii. Examples of Wind speed and air Volume Standards by Industry
The following are the reference standards for air velocity and air volume of box-type filters (classified by filtration grade) in typical industries. The data is based on industry norms (such as ISO 14644, GB 50457, ANSI/ASHRAE, etc.) and engineering practices:
Industry filtration scenarios: Filter type design, wind speed range, air volume design logic
Semiconductor/electronic cleanroom (Class 5-7) high-efficiency (HEPA) 0.3-0.5m /s high air volume (air change rate 100-300 times /h), ensuring no residue of fine dust (≤0.1μm), and strictly controlled air velocity (to prevent the diffusion and penetration of small particles)
Medium efficiency (F8-F9) in the changing room/buffer zone, with a medium air volume of 0.8-1.2 m/s (air change rate 30-60 times /h), is used to pre-treat atmospheric dust and protect the downstream high-efficiency filters.
In the pharmaceutical/biological aseptic workshop (Class A/B), the high-efficiency (HEPA) air volume of 0.4-0.6m /s should meet the "unidirectional flow" requirement (such as 0.45m/s±20%) to prevent cross-contamination of microorganisms, and the air velocity fluctuation should be ≤10%
Medium efficiency (F7) dust removal for active pharmaceutical ingredients: 1.0-1.5m /s, large air volume (calculated based on dust generation, usually ≥5000 m³/h), quickly captures powder particles (1-10μm)
The sub-high efficiency (H10) air volume in the clean filling area for food processing is 0.5-0.8 m/s, corresponding to an air change rate of 20-40 times per hour. Dust and microorganisms are controlled, and the air velocity is avoided from being too high to prevent products (such as powder) from flying.
The primary effect (G4) of the workshop ventilation pretreatment is 1.5-2.0 m/s, calculated based on the workshop volume (air change rate 10-15 times per hour), filtering large particles (such as insects and hair), and allowing for higher air velocity.
The medium-efficiency (F6) air volume of 1.2-2.5 m/s for industrial dust removal of welding/grinding fumes is designed based on the "capture speed" (for example, welding fumes need a wind speed of ≥2 m/s to be captured). A high wind speed is conducive to intercepting large particles (5-50μm).
The primary efficiency (G3) for building materials dust (cement/lime) is 2.0-3.0m /s with a large air volume (a single filter can reach 10,000-20,000m ³/h), which can quickly handle high-concentration dust and withstand high air speeds.
For ordinary buildings such as office buildings and shopping malls, the medium-efficiency (F5-F6) fresh air system has an air volume of 0.8-1.5 m/s. The air volume is adjusted according to the per capita demand (30-50 m³/h per person), and the air velocity balances energy consumption (if it is too high, the resistance will be large) and filtration efficiency.
The medium-efficiency (F8) ventilation in the hospital outpatient department has an air volume of 1.0-1.2 m/s, slightly higher than that of ordinary buildings (15-20 air changes per hour), to control pollen, bacteria, etc., and to avoid dust accumulation due to excessively low air velocity.
Iii. Core Reasons for the Differences
Different particle sizes of pollutants
The semiconductor industry focuses on "ultrafine dust" below 0.1μm and requires low wind speed (to extend the diffusion time and increase the capture rate of small particles).
Industrial dust removal focuses on "large particles" larger than 5μm and requires high wind speed (utilizing inertial collision to enhance the capture rate of large particles).
Mandatory requirements for cleanliness grades:
A Pharmaceutical Class A cleanroom requires "unidirectional flow", the air velocity must be stable at 0.45m/s±20% (GB 50457 standard), and the air volume needs to meet hundreds of air changes per hour.
There is no mandatory cleanliness in the ordinary workshop. The air volume only needs to meet the basic ventilation requirements (such as 10 times per hour), and the air velocity can be flexibly adjusted.
System energy consumption and cost balance
High-cleanliness industries (such as semiconductors) can accept high energy consumption (low air velocity + high air volume) to ensure product quality.
Industrial dust removal pays more attention to "low-cost treatment of large amounts of dust". High wind speed can reduce the number of filters (lower initial investment) and sacrifice some energy consumption.
Summary
There is no uniform value for the air velocity and air volume standards of box-type filters. Instead, they are jointly determined by the industry's cleanliness target, pollutant characteristics, and system functions. In practical applications, the design should be based on industry standards (such as national standards and international standards) and specific scenarios (such as dust generation and space size), combined with the rated parameters of the filter (the "air volume - resistance - efficiency" curve provided by the manufacturer). The core principle is: under the premise of meeting the filtration target, balance the air velocity (to ensure efficiency) and air volume (to ensure processing capacity).