A flammable gas alarm instrument is a safety device used to detect the concentration of flammable gases in the environment and issue an alarm signal when the concentration reaches a preset dangerous value. It is widely applied in places with the risk of flammable gas leakage, such as petroleum, chemical industry, gas, coal mining, and metallurgy industries. It is an important equipment to ensure production safety and personnel life safety.
How it works
Main Components
Sensor: As the core component, it is responsible for detecting the concentration of flammable gases. Common types include:
Catalytic combustion sensor: Suitable for most flammable gases. It generates signals through temperature changes of components caused by gas combustion.
Semiconductor sensor: Features high sensitivity and fast response, but has relatively poor selectivity.
Alarm controller: Receives signals from the sensor, processes and judges them. When the gas concentration exceeds the set threshold, it triggers the alarm device.
Alarm device: Usually includes an acoustic-optical alarm, which emits a sharp sound and flashing lights to alert on-site personnel.
Types of Detectable Gases
Specify the flammable gases that can be detected, such as methane (CH4), propane (C3H8), hydrogen (H2), acetylene (C2H2), ethanol (C2H5OH), etc.
Some instruments support multi-gas detection by replacing sensors (multi-gas type), and the range of compatible gases should be indicated.
Detection Principles
Corresponding to the sensor types:
Catalytic combustion type: Suitable for most flammable gases with a wide detection range.
Semiconductor type: High sensitivity, suitable for low-concentration detection.
Infrared type: Strong anti-toxicity and long service life, often used for specific gases such as methane.
Environmental Adaptation Parameters
Operating Temperature
Fixed type: -40ºC~+70ºC (for industrial scenarios, designed to withstand high and low temperatures).
Portable type: -20ºC~+50ºC (for daily inspections, in relatively mild environments).
Exceeding this range may affect sensor performance, requiring additional protection (such as thermal insulation or heat dissipation devices).
Operating Humidity
Typically 10%~95% RH (non-condensing). High-humidity environments (e.g., humid workshops) require moisture-proof design to prevent short circuits or sensor failure.
Explosion-Proof Rating
A critical parameter, such asEx d II CT6(flameproof type, suitable for Zone II, Category C explosive areas, with a maximum surface temperature ≤85ºC). The rating must be selected based on the explosion hazard level of the usage site to avoid the instrument becoming an ignition source.
Protection Rating
For example,IP65(completely dust-tight, protected against low-pressure water jets). Outdoor or dusty environments require a higher protection rating (IP66/IP67).
Technical features
Alarm Methods
Acoustic-optical alarm: Sound intensity ≥85dB (at 1 meter distance); light is red flashing (visual distance ≥20 meters).
Others: Vibration alarm (for portable devices), remote alarm (linked with control systems).
Signal Output
Analog quantity: 4-20mA current signal (long transmission distance, suitable for connecting to PLC/DCS systems).
Digital quantity:
RS485 (Modbus protocol, facilitating data upload to monitoring platforms).
Switch quantity (for interlocking with valves/fans, usually with a capacity of AC220V 5A).
Working Principle
When the sensor comes into contact with flammable gases, physical or chemical reactions occur (for example, a catalytic combustion sensor will experience temperature changes due to gas combustion, which in turn changes its resistance), generating electrical signals related to gas concentration. These signals are transmitted to the alarm controller, which analyzes and processes them. When the concentration exceeds the preset alarm value, the alarm device is activated immediately. Meanwhile, control signals may be output (such as shutting off gas valves, starting exhaust equipment, etc.).
Maintenance and Calibration
To ensure the accuracy and reliability of the instrument's detection, regular maintenance and calibration are required:
Clean the sensor regularly to prevent dust, oil stains, etc., from affecting detection accuracy.
Calibrate with standard gas regularly according to the instructions to ensure the alarm threshold is accurate.
Check whether the alarm device works normally to ensure the sound and light alarm functions are intact.
Company Profile
Address: Huji Industrial Park, Deshang Expressway, Mudan District, Heze City, Shandong Province, China
Business type: Manufacturer/factory, trading company
Business scope: manufacturing and processing machinery
Management system certification: ISO9001:2015 ISO45001:2018 ISO14001:2015
Main products: Ground flare, Biogas flares, flare stack,
Thermal Oxidation Furnace, Flue gas purification equipment
Heze Zexuan Equipment Manufacturing Co., Ltd. is an enterprise engaged in the manufacture of special equipment for environmental protection; sales of special equipment for environmental protection; application of industrial automation technology; sales of power electronic components; research and development of mechanical equipment; sales of intelligent instruments and meters; manufacturing of intelligent instruments and meters; research and development and promotion of comprehensive utilization of waste gas and VOCs treatment technology.
The company's main products and service directions: manufacturing of ground torches, elevated torches, waste gas venting torches, biogas torches, three waste incinerators, and wastewater treatment equipment, industrial automation and DCS system applications, wastewater treatment projects, VOCs treatment equipment and engineering construction, petrochemical accessories and instrument sales, petrochemical equipment installation, maintenance and repair, etc.; support product customization services and OEM services in the same industry, from design to manufacturing, installation, commissioning, and after-sales one-stop service.
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