Selection Principles for Hazardous Gas Detection and Alarm Instruments
1. In short, the detection of harmful gases has two purposes: firstly, to detect explosions, and secondly, to detect toxins. The so-called explosion testing is to detect the combustible gas content in hazardous areas, issue an alarm if it exceeds the standard, in order to avoid the occurrence of explosion accidents; Poison testing is the process of detecting the concentration of toxic gases in hazardous areas, triggering an alarm if they exceed the limit, in order to prevent staff from being poisoned. The range of explosive testing is 0-100% LEL, and the range of toxin testing is 0-100 (or hundreds) ppm, with a significant difference between the two. There are three types of harmful gases in hazardous areas: first, non-toxic (or low toxicity) and flammable; second, non flammable and toxic; and third, flammable and toxic. The first two situations are easy to determine. The first is to test for explosives, the second is to test for toxins, and the third is to test for explosives if there are personnel exposed. If there are no personnel exposed, explosives can be tested. Choose combustible gas detection alarm for explosion testing and toxic gas detection alarm for toxicity testing.
2. Clearly define the testing purpose and select the type of instrument (portable or fixed). For long-term operation of leak detection in production or storage positions, use fixed detection alarm devices; Portable (or pocket sized) instruments are used for other purposes such as maintenance and inspection, emergency testing, entry testing, and patrol testing. The instrument model includes three main contents: manufacturer, functional indicators, and testing principles.
3. Clarify the testing object and select the optimal instrument model. When choosing an instrument model, the following principles should be considered:
① The manufacturer emphasizes integrity, good reputation, and guaranteed production quality. It has passed the ISO9002 quality system certification, obtained the CMC production license issued by the technical supervision department, and has fire and explosion prevention certificates.
② The selected model product's functional indicators should comply with the requirements of national standards such as GB12358-90, GB15322-94, GB16808-1997, etc.
③ The detection principle of the instrument should adapt to the requirements of the detection object and the detection environment.
Harmful gas sensors and their characteristics
Overview of harmful gas sensing: Harmful gas sensors are devices that convert harmful gas content in the air into electrical signals. The electrical signals generated by sensors are processed, amplified, and used on site by electronic circuits, which can withstand various harsh environments and atmospheres. Especially for sensors of fixed instruments, which operate continuously for a long time and are limited by explosion-proof and power supply capacity, the requirements for harmful gas sensors are very strict. After conversion, display and alarm harmful gas content. It can be seen that sensors are the fundamental and core components of harmful gas detection and alarm devices, and their advantages and disadvantages determine the quality and functional indicators of harmful gas detection and alarm devices.
