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Selection and Application of Environmental gas detection and alarm Instruments in the workplace
Gas detection and alarm instruments belong to the accident prevention facilities in the production safety facilities of enterprises.In places where flammable, explosive, toxic and harmful gases are involved during production and storage and transportation, enterprises need to install gas detection and alarm instruments for real-time monitoring and timely alarm to prevent personal injury, fire and explosion accidents and ensure the safe operation of enterprise production.
This article provides a detailed introduction from multiple aspects, offering references for enterprises in the selection and application of gas detection and alarm instruments.
1. In which places should gas detection and alarm instruments be installed
Civilian Premises
● Households and residential areas, gas-consuming regions such as kitchens with gas water heaters and stoves installed.
● In the kitchen operation areas of restaurants and canteens, one combustible gas alarm should be installed for every 50 square meters of gas stoves, and the horizontal distance from the release source (such as valves and pipe joints) should be no more than 5 meters.
● Portable four-in-one Gas Detectors (capable of detecting flammable gases, oxygen, carbon monoxide and hydrogen sulfide) should be installed at the entrances of gas pipeline Wells, sewage Wells and other facilities in basements and underground garages.
● Oxygen detection and alarm devices should be installed in the rooms of the centralized oxygen supply system in nursing homes or hospitals. The set values for oxygen deficiency alarm are 19.5%VOL, and for oxygen enrichment alarm, they are 23.5%VOL.
Industrial Site
● Combustible gas detectors must be installed in places involving the use of gas.
● Places involving the production, storage and use of flammable gases and liquids with fire hazard categories of Class A and B must be equipped with flammable gas detectors.
● In production, storage and use sites involving flammable liquids with a fire hazard category of Class C, when the operating temperature exceeds the flash point of such Class C liquids, flammable gas detectors should be installed.
● During storage, when substances may produce flammable gases upon contact with water, combustible gas detectors (such as in calcium carbide warehouses) should be installed.
● When the production, storage and use of substances involving the installation of Toxic Gas Detectors are carried out, toxic gas detectors should be installed.
● In general, in the operation area of a chemical and chemical engineering laboratory, combustible and toxic gas detectors do not need to be installed, but in the reagent storage area, detectors should be installed.
● Oxygen concentration detectors should be installed in closed or semi-closed places where oxygen or inert gases are stored, used, or where large amounts of oxygen or inert gases may be produced.
2. Detection Objects and Principles of Gas Detection Alarms
Gas detection object
● Flammable gas: A gas that, when mixed with air in a certain proportion, will form an explosive environment.
● Toxic and harmful gases: Gases that cause harm, illness or death to people when exposed to or inhaled at certain concentrations.
● Oxygen: The volume fraction of oxygen in the air is approximately 20.9%. When the oxygen content drops below 19.5%, it is considered hypoxia. Hypoxia can affect multiple systems and organs in the human body and even be fatal.
| Serial number | Classification of detection principles | Principle | Key conditions/characteristics |
| 1 | Catalytic combustion type | Under the action of a catalyst (such as a platinum wire), flammable gases undergo flameless combustion, releasing heat that raises the temperature of the detection element, causing a change in resistance value (Wheatstone bridge principle), and generating an electrical signal proportional to the gas concentration | Oxygen is required (failure in an oxygen-free environment), and it is easily affected by poisoning from substances such as sulfides and silicones Application: Mainly used for the detection of flammable gases (methane, propane, etc.), the output signal is displayed in %LEL |
| 2 | Electrochemical type | The gas to be measured diffuses through the breathable membrane to the working electrode in the electrolyte, where oxidation/reduction reactions occur, generating a weak current signal proportional to the concentration | It requires a small amount of oxygen to maintain its function, is affected by changes in humidity and pressure, and has high selectivity for specific toxic gases (such as CO and H₂S) Application: PPM-level toxic gas detection, such as industrial Toxic Gas Alarms and household carbon monoxide alarms |
| 3 | Photoionization （PID） | By using ultraviolet light sources (high-energy photons) to excite gas molecules to ionize, positive and negative polarity ions are generated, forming a current signal proportional to the concentration. After ionization, the molecules can recombine without being damaged | High sensitivity (ppb level), suitable for the detection of volatile organic compounds (VOCS) |
| 4 | Infrared type | Based on the absorption characteristics of gas molecules to infrared light of specific wavelengths, the concentration is calculated by measuring the degree of attenuation of infrared light intensity, including a light source, a measurement gas chamber, a reference gas chamber and a detector | It has strong anti-poisoning ability, does not require oxygen, has a long service life (5-10 years), and is suitable for hydrocarbons and CO₂ Wait for testing |
3. The equipment composition can be divided into system type and independent type
● Systematic gas detection and alarm instrument
A networked detection system composed of multiple gas detectors, a data acquisition controller (host), and an upper computer monitoring system supports centralized monitoring, data storage, and remote alarm.
Gas detectors (distributed installation) : Deployed at multiple points, they collect on-site gas concentrations in real time and output signals.
Controller/Host：Receives detector signals, displays concentration, triggers sound and light alarms, and supports interlocking exhaust, shut-off valves and other devices.
Upper computer software：Connected to the host via bus or wireless network, it realizes data recording, curve analysis, historical query and report generation.
Typical application scenarios：petrochemical production workshops, storage tank areas, and along long-distance pipelines; Underground coal mines, metallurgical plant areas and other places that require multi-regional collaborative monitoring.
● Independent gas detection and alarm instrument
A portable or fixed single device integrating sensors, alarms and power sources, which does not require networking and can independently complete detection and alarm functions.
Integrated design: The sensor module, microprocessor, sound and light alarm unit, and battery/power module are all integrated in a single housing.
Local alarm: When the concentration exceeds the standard, the built-in buzzer and LED indicator light will be triggered to alarm. Some models support vibration alarm (portable).
Typical application scenarios: laboratories, small warehouses, and confined space operations (such as sewer and storage tank maintenance); Household gas leakage detection, portable personal protection (such as painters, gas inspectors).
Selection suggestion: Choose based on the area of the workplace, the risk level of gas leakage and management requirements.For high-risk and large-scale areas, systematic methods should be given priority. Temporary work or small Spaces can be complemented by standalone equipment.
4. Requirements for the installation height of Combustible/Toxic Gas Alarms
| Serial number | Classification | Installation height | Basis |
| 1 | Gases heavier than air (such as liquefied petroleum gas and propane) | It is 0.3 to 0.6 meters away from the ground level (or floor)(Special scenarios: In basements or low-lying areas, the installation height should be reduced to 15 to 30 centimeters. Within 1 meter of the leakage point at the bottom of industrial storage tanks, the installation height should be 0.3 to 0.5 meters.) | Heavy gas leakage is prone to sink and accumulate. Installing it close to the ground can quickly detect the accumulation layer |
| 2 | Gases lighter than air (such as natural gas and hydrogen) | It is advisable to be 0.5 to 2 meters higher than the release source or no more than 30 centimeters from the roof(Special scenario: In a closed factory building, dual deployment should be carried out above the release source and at the highest point of the factory building (where accumulation is likely to occur). | When light gas leaks, it will float up and the upward path of the gas needs to be covered |
| 3 | Gases with a density close to that of air (such as carbon monoxide and hydrogen cyanide) | It is 1 to 1.5 meters above the ground, or within 1 meter above or below the release source | Such gases are prone to mixing and diffusing with air, so vertical space coverage must be taken into account |
5. New 4G Wireless Gas Detector
In some special places where there is no power supply or wiring is difficult (such as gas stations, chemical tank farms, etc.), enterprises can adopt new 4G wireless gas detectors powered by lithium batteries, which integrate advanced sensor technology and wireless communication functions (such as LoRa, NB-IoT/4G), and have the core advantages of low power consumption, no wiring required, and rapid deployment.
Core technical features
● battery power supply and ultra-low power consumption
It adopts a 3.8V lithium battery (with a capacity of 16-50Ah, customizable), combined with an intelligent power consumption management algorithm to achieve an ultra-long standby time of up to 2 years and a service life of up to 5 years.By using low-power infrared sensors and MEMS technology (such as the Figaro TGS8410 sensor with a power consumption of only 0.087mW), energy consumption is reduced and detection sensitivity is enhanced.
Instruments powered by batteries have the functions of battery level display or low battery prompt.Rechargeable instrument with charging display function. When the battery of an instrument powered by batteries is low, it can emit an audible or visual display signal that is different from the alarm signal.
● Wireless transmission and convenient installation
Supports wireless protocols such as LoRa and 4G to achieve real-time remote data transmission and centralized monitoring (for example, MIC-600-L-Ex can be connected to the MIC3000 controller to manage 1,000 devices)；Magnetic installation design, deployment can be completed within 30 seconds without drilling or wiring, and is compatible with metal surfaces (such as near fuel dispensers at gas stations).
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