I. What is Filtration Accuracy?
Filtration accuracy refers to the smallest dust particle diameter that a filter element can effectively capture, usually measured in micrometers (μm).
Simply put: the smaller the accuracy value, the finer the dust particles it can filter, resulting in a more refined filtration effect.
Common filtration accuracy levels in industrial dust removal:
Above 10μm: Coarse filtration, suitable for large particles and heavier dust.
5～10μm: General-purpose conventional filtration.
1～5μm: Fine filtration, suitable for most industrial conditions.
0.3～1μm: Ultra-fine filtration, mostly used for ultrafine powders and scenarios with strict environmental emission requirements.
II. What is Filtration Efficiency?
Filtration efficiency refers to the percentage of dust captured by a filter element, reflecting its filtration capacity.
Common representations:
99%
99.5%
99.9%
99.99% (High Efficiency Level)
The higher the filtration efficiency, the less dust escapes, making it easier to meet environmental emission standards.
Generally, 99% or higher is required for normal operating conditions, while strict emissions require 99.9% or even higher.
III. Relationship between Filtration Precision and Efficiency
Higher precision usually means higher efficiency.
It can capture finer dust particles with a lower escape rate.
Excessive precision can lead to increased resistance.
Denseer filter media results in greater air resistance, increased fan load, and higher power consumption.
Blindly pursuing high precision can easily cause clogging.
Ultra-fine dust easily adheres to the filter media surface, making cleaning difficult and significantly shortening the filter element's lifespan.
Therefore, the selection principle is: sufficient for current needs, with suitability as a priority.
IV. How to match filtration accuracy and efficiency for different dust conditions?
Large Particle Coarse Dust
e.g., sawdust, sand, grain dust, crushing dust
Recommended filtration accuracy: 5–10 μm
Efficiency requirement: around 99%
Features: Good air permeability, not prone to clogging, stable operation
Conventional Industrial Dust
e.g., metal grinding, cutting, welding fumes, ordinary powders
Recommended filtration accuracy: 1–5 μm
Efficiency requirement: above 99.5%
Features: Balances filtration effect and service lifeUltrafine, lightweight dust
e.g., carbon black, coating powder, pigment powder, chemical micro-powder, pharmaceutical dust
Recommended precision: 0.3–1 μm
Efficiency requirement: 99.9% or higher
Characteristics: High precision is essential; otherwise, emissions may exceed standards.
High-humidity, sticky dust
e.g., damp coal dust, sludge dust, oily dust
Blindly increasing precision is not recommended.
Prioritize PTFE membrane-coated, oil- and water-resistant filter media, relying on structural design to achieve efficient dust removal.
V. Key Factors Affecting Filtration Efficiency
Filter Media Material
Ordinary Polyester < Membrane-coated Polyester < Antistatic Filter Media < High-Temperature Special Filter Media
Surface Filtration Structure
PTFE membrane achieves surface filtration, preventing dust from penetrating the filter layer and resulting in more stable efficiency.
Filtration Velocity
Excessive air velocity will disperse the dust layer, reducing efficiency; insufficient air velocity will affect throughput.
Dust Removal System Matching
Timely dust removal and keeping the filter element clean are essential for long-term stable efficiency.
Installation Sealing
Poor sealing can lead to short circuits and dust leakage, directly causing filtration failure.
VI. Common Selection Misconceptions
Misconception: Higher filtration precision means a better filter element.
Truth: Excessive precision increases resistance and shortens lifespan; suitability is key.
Misconception: Focusing only on efficiency without considering operating conditions.
Truth: High efficiency alone is meaningless in high-concentration, high-humidity, and high-temperature environments.
Misconception: Cheap filter elements can achieve the stated precision.
Truth: Inferior filter media often have falsely advertised precision, resulting in low actual efficiency and potentially leading to non-compliance with emission standards.
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