作为仪器仪表的一个重要分支，气体检测仪器仪表(也称“气体探测器”)应用领域广泛，覆盖了工业、农业、交通、科技、环保、国防、航天航空及日常生活等各方面。通常，工业过程气体监控分析仪器划归分析仪器领域，常见的气体检测仪器仪表通常小型化、便携或固定式、独立工作或联成网络，广泛适用于石油、化工、冶金、采矿、制药、半导体加工、喷涂包装等工业现场和家庭、商场、液化气站、煤气站、加油站等民用/商用需防火防爆、预防中毒、空气污染的场所，以及农业温室气体检测、沼气分析和沼气安全监控和环保应急事故、恐怖袭击、危险品储运等方面[1]。
As an important branch of instrumentation, gas detection instruments (also known as "gas detectors") are widely used in various fields, including industry, agriculture, transportation, technology, environmental protection, national defense, aerospace, and daily life. Usually, industrial process gas monitoring and analysis instruments are classified under the field of analytical instruments. Common gas detection instruments are usually miniaturized, portable or fixed, working independently or connected to a network, and are widely used in industrial sites such as petroleum, chemical, metallurgy, mining, pharmaceuticals, semiconductor processing, spray coating packaging, as well as in residential/commercial areas such as homes, shopping malls, liquefied gas stations, gas stations, and gas stations that require fire and explosion prevention, poisoning prevention, etc Places with air pollution, as well as agricultural greenhouse gas detection, biogas analysis, biogas safety monitoring, environmental emergency accidents, terrorist attacks, hazardous material storage and transportation, etc. [1].
气体检测仪是一种气体泄露浓度检测的仪器仪表工具，主要是指手持式/固定式气体检测仪。主要利用气体传感器来检测环境中存在的气体种类。
Gas detector is an instrument tool for detecting gas leakage concentration, mainly referring to handheld/fixed gas detectors. Mainly using gas sensors to detect the types of gases present in the environment.
气体检测仪中的0-100% LEL与0-n PPM
0-100% LEL and 0-n PPM in gas detectors
（1）“LEL"是指爆炸下限。 可燃气体在空气中遇明火种爆炸的最低浓度，称为爆炸下限—简称%LEL。英文：Lower Explosion Limited。 可燃气体在空气中遇明火种爆炸的最高浓度，称为爆炸上限—简称%UEL。英文：Upper Explosion Limited。 那么什么是爆炸下限？ 可燃性气体的浓度过低或过高它是没有危险的，它只有与空气混合形成混合气或更确切地说遇到氧气形成一定比例的混合气才会发生燃烧或爆炸。燃烧是伴有发光发热的激烈氧化反应，它必须具备三个要素：a、可燃物（燃气）；b、助燃物（氧气）；c、点火源（温度）。可燃气的燃烧可以分为两类，一类是扩散燃烧，即挥发的或从设备中喷出、泄漏的可燃气，遇到点火源混合燃烧。另一类燃烧，是可燃气与空气混合着火燃烧，这种燃烧反应激烈而速度快
(1) LEL "It refers to the lower explosive limit. The minimum concentration at which a combustible gas can explode when exposed to a flame in the air is called the lower explosive limit (LEL)." Combustion or explosion only occurs when a mixture is formed or, more precisely, when it encounters oxygen to form a certain proportion of the mixture. Combustion is an intense oxidation reaction accompanied by luminescence and heating, which must have three elements: a. Combustible substances (gas); b. Combustible materials (oxygen); c. The ignition source (temperature). The combustion of combustible gas can be divided into two types. One type is diffusion combustion, which means that volatile or leaked combustible gas is mixed and burned when encountering an ignition source. Another type of combustion is the combustion of combustible gas mixed with air, which is intense and fast in reaction