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Particle measurement method and particle sensor module are recommended

Update: 2020-10-26 15:09 Source: LUFTMY Reading: ↻ News

Particulate matter, also known as dust, a variety of solid or liquid particles uniformly dispersed in an aerosol system.Particulate matter can be divided into primary particulate matter and secondary particulate matter.Primary particulate matter is the particulate matter that is released into the atmosphere by direct sources of pollution, such as soil particles, sea salt particles, burning soot and so on.Some secondary particulate matter is made up of the atmosphere pollution gas composition (such as sulfur dioxide, nitrogen oxides, hydrocarbons, etc.), or the components and normal components, such as oxygen from the atmosphere by photochemical oxidation, catalytic oxidation reaction between conversion generated particles or other chemical reaction, such as sulfur dioxide conversion generated sulfate.

Particle measurement method and particle sensor module are recommended

Classification of particulate Matter

Current has aroused much attention of particulate matter can be divided into two categories: PM2.5 (fine particulate matter, the "thin" here take the first meaning of Chinese characters: small particles, as opposed to a "rough") and PM10 (PM10), the former is less than 2.5 microns in diameter, the diameter of a human hair is one over thirty, the latter is bulky, the current set of eu air quality standards of PM2.5 in average for a maximum of 40 micrograms per cubic meter, PM10 is 25 micrograms per cubic meter.Guidelines from the United Nations World Health Organization recommend an annual average of 20 micrograms per cubic meter for PM2.5 and 10 micrograms per cubic meter for PM10.

There is no unified classification method for particulate matter, which can be divided into drifting dust and falling dust according to the settling characteristics of dust under the action of gravity.Conventionally divided into:

Dust particles: coarse particles with a particle size greater than 75 microns.

(2) Dust: particle size of 1 to 75 microns, generally produced by the industrial production of crushing and running operations.

Submicro dust: dust with particle size less than 1 micron.

Fishing trawl (TAI) : solid particles formed during combustion, sublimation, condensation, etc., with particle size generally less than 1 micron.

(5) Fog dust: condensation and condensation of supersaturated steam in industrial production, chemical reaction and liquid spray formed by droplets.Particle size is generally less than 10 microns.By supersaturated vapor condensation and condensation of liquid fog is also known as haze.

Smoke: An inhomogeneous system of solid particles and droplets, including soot and soot, with particle sizes of 0.01 to 1 micron.

Chemical smoke: divided into sulfuric acid smoke and photochemical smoke two kinds.Sulphuric acid smog, also known as London-type smog, is a chemical result of the mixing of sulphur dioxide or other sulphides, unburnt coal dust and high concentrations of aerosol dust.Photochemical smog, also known as Los Angeles-type smog, is formed by photochemical reactions of hydrocarbons and nitrogen oxides in car exhaust.

(8) soot: coal incomplete combustion produced by the carbon particles or the combustion process produced fly ash, particle size of 0.01 ~ 1 micron.

Pet-dust (pet-dust) : Unburned particles of coal carried off by flue gas.

Difference: Dust particles with different particle sizes have different settling characteristics under the action of gravity. For example, particles with particle size less than 10 microns can float in the air for a long time, which is called drifting dust. Among them, particles with particle size less than 0.1 microns are also called cloud dust.Particles with a particle size greater than 10 microns can settle quickly, so it is called dust removal.

Measurement of particulate matter

The dust weight (in micrograms or milligrams) per unit volume of the gas in its standard state (i.e., 76cmhg at pressure and 273K at temperature) is known as the dust concentration.The main determination methods are:

(1) Gravimetric method, also known as gravimetric concentration method, the use of filters or other separator to collect dust and weighing method, is a reliable method for the determination of dust content.

(2) Light scattering method: The laser dust meter has a new type of on-line filter film sampler with international advanced level in the new century. The instrument can collect the particles while continuously monitoring the dust concentration, so as to analyze its components and calculate the mass concentration conversion coefficient K value.

Comparison method of concentration specification table: The lindman soot concentration table proposed by M.R. Lindman is widely used.

Photometry method: use of a certain intensity of light through the measured gas, gas or water washing a certain amount of test, the dust particles in the gas in the water, and then with a certain intensity of light through the dusty water, gas or dust particles in the water on the light reflection and scattering phenomenon, photoelectric device is used to test the transmission light or scattering light intensity, and compared with the standard luminosity, can be converted to dust concentration.

(5) : the calculation method of particle is known of the dust in the air volume is deposited in a transparent surface, and then under the microscope to count the number of dust particles, and the results measured in the number of particles within per cubic centimeter, said, when necessary, can be converted to dust concentration, the conversion of approximation is: there are 500 dust particles per cubic centimeter, dust concentration of equivalent in standard condition about 2 mg per cubic meter, 2000 dust particles approximately 10 milligrams per cubic metre, 20000 dust particles is about 100 mg per cubic meter.

Recommended for particle sensor module: LD15 Laser PM2.5 Dust Sensor Model

LD15 Laser PM2.5 Dust Sensor Model

The diameter of detected particle is 0.1~10um

The mi scattering principle is adopted

The service life of electronic control devices is ≥8 years, and the average trouble-free working time is ≥5 years

Small size, low power consumption

Wide range of applications, no need for duct design, compatible with multi-protocol output.

Online application

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