The free silica detector and dust free silica detector are upgraded industry products based on the original infrared spectrophotometer. This product is mainly used for the analysis and testing of dust in production environments such as power and coal industries. It mainly includes silicon dust, coal dust, boiler dust, asbestos dust, cement dust, welding fumes, etc. Its characteristics are that the content of free silica in the dust is high, and the dispersion of the dust is also relatively high, which is mostly respiratory dust. Therefore, it poses a greater risk to personnel exposed to dust. According to the physical and chemical properties of productive dust, the concentration in the air, the amount of dust entering the human body, and the affected areas, the hazards produced also vary, mainly including respiratory diseases such as rhinitis, pharyngitis, tracheitis, bronchitis, etc. The Chinese government, as well as the power and coal industries, attach great importance to dust prevention work. Therefore, strengthening the detection of free silica content in dust is a very important and urgent task. In the past, the detection of free silica content in dust was carried out using the "pyrophosphate gravimetric method" specified in the "Method for Determination of Dust in Workplace Air" (GB5748-85). This method has a series of problems such as complex operating steps, a wide variety of reagents used, long detection cycles, poor accuracy, and strict laboratory conditions, which make it difficult to meet the requirements of on-site batch testing. In order to improve the accuracy of detection and achieve the purpose of batch detection, a TFD-4000 dust free silica detector has been specially developed to detect the content of free silica in dust. (Can be used for quantitative analysis) (Complies with the National Occupational Health Standard GBZ/T192.4-2007 for determination of dust in workplace air)

Free silica detector, dust free silica detector. Main data processing functions:

Data processing function - easily handle analysis results, including peak calibration, peak area integration, baseline calibration, and other operations;

Quickly create and print experimental reports;

Standard file format - Maintain experimental results for easy sharing and processing;

Spectral file storage and printing;

Spectral background baseline memory Spectral background baseline correction Spectral data accumulation calculation% T and ABS conversion.

Performance indicators of free silica detector in dust:

Wavelength range: 2.5-25um (wavenumber range: 4000-400cm-1);

Wave number accuracy: ≤± 2cm-1 (2000-400cm-1);

≤± 4cm-1 (4000-2000cm-1);

The full wavelength scanning slit program is adjustable in five levels;

Scattered light ≤ 0.5% T (4000-650cm-1);

≤ 1% T (650-400cm-1);

Transmittance accuracy: ≤± 0.2% T (excluding noise level);

Grind the sample to a particle size of less than 8Lm;

Built in high-end computer, equipped with Windows XP operating system, Chinese operating platform, USB 2.0 interface.

Free silica detector, dust free silica detector features:

1. It has the characteristics of being fast, sensitive, and able to identify the three crystal forms of free silica, but due to its low equipment investment and operation.

The advantages of simplicity and suitability for automatic analysis have been widely applied.

3. The sturdy design and practical exterior dimensions are suitable for various analysis and testing environments.

4. Excellent sensitivity and signal-to-noise ratio.

5. Integrate detection components, signal amplifiers, and 24 bit analog-to-digital converters together to directly output digital signals (analog signals experience significant attenuation and are susceptible to interference during transmission, while digital signals can be avoided), further reducing electronic noise; The 24 bit analog-to-digital converter enhances the weak signal detection capability of the system by an order of magnitude.

6. High performance computers are used for instrument control and data processing, with a WINDWOS fully Chinese operating interface.

The moving parts composed of electromagnetic drive devices and precision mechanical guide rails have improved the requirements for the usage environment.

8. The high-intensity light source adopts a spherical reflection device, which can obtain uniform and stable infrared radiation.

The chemical method used in the free silica detector utilizes the reaction between silicon components in the sample and acid and molybdate reagents to form yellow molybdosilicate complexes. Select acid conditions to specifically form β - molybdosilicic acid, while excluding interference from other acid complexes. In order to improve the sensitivity of this method, yellow acid is reduced to its blue form, which can be measured by colorimetric method in an optical system. The sequence of events is:

a) Add sulfuric acid (acid reagent) to the sample to reduce the pH to between 1.4 and 1.8.

b) Add ammonium molybdate to the acidified sample.

c) The solution enters the reaction coil in the temperature control block (providing a 2-minute delay), where yellow β - molybdosilicic acid is formed.

d) Before the solution enters the second reaction coil in the temperature control block (providing a 2-minute delay), add sulfuric acid and citric acid to further reduce the solution to between 0.8 and 1.0. This is the pH value required to stop further reactions of silicon and provide conditions for the next reaction (reduction). In applications where the sample contains phosphate, increasing the concentration of citric acid can disrupt any phosphate complexes, which may increase the color formed in the next step.

e) Add the reducing solution before entering the third reaction coil in the temperature control block (providing a 1-minute delay) to reduce the yellow complex to its blue form.

f) The fully reacted solution enters the measuring colorimetric cell in the optical system, where the intensity of the color is measured (proportional to the original concentration of silica).

g) During automatic zero point calibration, the monitor generates a zero point solution by transferring the sample to the point where the second acid solution is added. The pH value at this point is too low to allow the silica molybdate reaction to occur, resulting in a solution with zero silica concentration. In zero point calibration, the system allows the reaction of silica in acid solution and molybdate solution. By automatically introducing standard solutions with known values, auxiliary advanced verification can be performed.