Dust concentration detector is an instrument used to measure the concentration of suspended particulate matter (dust) in the air, widely used in industrial dust removal, environmental monitoring, occupational health and other fields.

1、 Optical principle of dust concentration detector (mainstream technology)

1. Light scattering method (LS)

Principle:

The instrument emits a beam of light, and when the light passes through dusty air, the dust particles scatter the light. By detecting the intensity of scattered light and combining it with preset calibration parameters, calculate the dust concentration.

Features:

High sensitivity: capable of detecting low concentrations of dust concentration.

Real time performance: Fast response time (in milliseconds), suitable for online monitoring.

Widely applicable: suitable for measuring PM2.5, PM10, workshop dust, etc.

局限性：

There is a significant error in dealing with ultrafine particles (such as nanoscale) or high humidity environments.

Regular calibration is required to avoid optical lens contamination.

2. Light transmission method (also known as extinction method)

Principle:

Calculate dust concentration by measuring the intensity difference (extinction ratio) between incident light and transmitted light. The more dust there is, the weaker the transmitted light.

Features:

Simple structure: only one light source and receiver are needed, suitable for low-cost devices.

Suitable for high concentration: More stable measurement for high concentration dust (such as mines, cement plants).

局限性：

Due to significant interference from ambient light, it needs to be installed in a dark environment.

Cannot distinguish particle size, only reflects total concentration.

3. Beta ray absorption method

Principle:

Using beta rays to penetrate dust samples and calculating dust mass concentration by measuring the degree of radiation attenuation.

Features:

High precision: can directly measure mass concentration without assuming particle density.

Strong anti-interference: not affected by particle shape, color, or humidity.

局限性：

The use of radioactive materials requires strict protection and regular maintenance.

The equipment is complex and costly, with a slow response speed (in minutes).

2、 Principle of charge induction in dust concentration detector

1. Electrostatic induction method

Principle:

Dust particles are frictionally charged in the airflow, and their concentration is inferred by measuring the amount of charge carried by the particles.

Features:

No need for light source: suitable for high dust concentration or flammable and explosive environments.

Simple structure: no optical components, low maintenance cost.

局限性：

Highly affected by humidity (charges are easily dissipated in humid environments).

Unable to distinguish particle size, calibration with other methods is required.

2. Capacitive sensors

Principle:

Calculate the concentration by measuring the capacitance changes caused by dust deposition.

Features:

Low cost: commonly used for simple dust alarms.

Pollution resistance: suitable for situations where dust accumulates for a long time.

局限性：

Low precision, susceptible to temperature and humidity interference.

Frequent cleaning is required to maintain sensitivity.