Dynamic air-distributing device for formaldehyde standard gas

Abstract

Disclosed is a device for dynamically allocating formaldehyde standard gas. The device comprises a gas allocating system and a cracking device, a gas source connected with a pressure-regulated valve, a gas purifier which one end is connected with the pressure-regulated valve, and the other end is connected with a mass flow meter, a mass flow meter connected with two rotor flow meters, wherein one rotor flow meter is connected with a constant temperature slot in which is installed with paraformaldehyde diffusing pipe, the paraformaldehyde high temperature catalyzing cracking device is installed between the constant temperature slot and the air mixer, and the other rotor flow meter connected with the air mixer; and the air mixer is individually connected with an redundant air exhausting valve and a standard air outlet control valve.

Description

technical field [0001] The invention relates to a dynamic gas distribution device for formaldehyde standard gas, which belongs to the method of dynamically generating formaldehyde standard gas by using a paraformaldehyde diffusion tube and a chemical cracking method to verify and calibrate formaldehyde content detectors in indoor and outdoor air, test formaldehyde analysis and test methods and carry out Analytical quality control, etc. Background technique [0002] At present, in the field of environmental monitoring, such as air pollution monitoring, indoor air quality monitoring and other applications, standard gases are widely used for measurement and evaluation. The standard gases in cylinders of such gases prepared by weighing methods in China are uncertain. High accuracy and poor stability, most of them cannot meet the required measurement accuracy and stability, which seriously restricts the accurate measurement and traceability of trace components of this type of gas...

AI Technical Summary

Problems solved by technology

[0002] At present, in the field of environmental monitoring, such as air pollution monitoring, indoor air quality monitoring and other applications, standard gases are widely used for measurement and evaluation. The standard gases in cylinders of such gases prepared by weighing methods in China are uncertain. High accuracy and poor stability, most of them cannot meet the required measurement accuracy and stability, which seriously restricts the accurate measurement and traceability of trace components of this type of gas, and the development of new gas distribution methods for this type of standard gas The research is particularly urgent; in the early 1980s, the dynamic gas distribution method of the volatile, corrosive, and adsorptive standard gases of the ISO 6145 series of standards was recommended, and it was revised in the late 1990s. The ISO 6145 series of standards pointed out that the dynamic gas distribution method Gas diffusion tube method, permeation tube method, etc. showed lower uncertainty (1% to 3%) in the preparation of volatile, corrosive, and adsorptive standard gases; in 1978, the American Analytical Instrument Development Corporation developed a product In 1980, the International Organization for Standardization (ISO) recommended the diffusion tube method as a standard gas distribution method; in 1981, the American Bureau of Standards (NBS) published a similar In the 1980s, Japan also published research papers; China also had similar research in the early 1980s, but due to limited conditions, it failed to achieve a substantial application stage; in the 1990s, a series of diffusion Control the application of organic standard gas; China's health standards stipulate that the maximum allowable concentration of formaldehyde in the atmosphere of residential areas (one-time maximum) is 0.08mg / m 3 , the concentration of formaldehyde in the air of public places shall not exceed 0.12mg / m 3 , in order to correctly measure and evaluate the degree of indoor formaldehyde pollution, it is necessary to prepare corresponding low-concentration formaldehyde gas standard substances in the air to calibrate formaldehyde analysis instruments, test formaldehyde analysis test methods, provide quality control and assurance of formaldehyde analysis, and ensure the uniformity of formaldehyde measurement values and traceability of measurement results

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