The fixed LPG liquefied petroleum gas alarm mainly consists of two parts: the LPG leak detector and the gas alarm controller. The detector can be used independently and can be equipped with sound and light alarm and on-site display functions, but it requires 24V power supply. If the detector is used in conjunction with the controller, only 220V power supply is required.
In the industrial field, catalytic combustion sensors, due to their cost-effectiveness and reliability, are the universal main force for monitoring the explosion risk of flammable gases. Catalytic combustion gas sensors operate based on the thermal effect principle of catalytic combustion. Under certain temperature conditions, combustible gases undergo flameless combustion on the surface of the detection element carrier and under the action of the catalyst, outputting an electrical signal proportional to the concentration of the combustible gas. The concentration of flammable gas can be known by measuring the magnitude of the resistance change of the platinum wire. It is mainly used for the detection of flammable gases, featuring good linearity of output signals, reliable index, low cost, and no cross-reaction with other non-flammable gases.
The specific working principle is as follows
1.Heating and balancing: The two components are heated by current to a working temperature of approximately 500°C. In pure air, the bridge is in a balanced state and the output signal is zero.
2. Catalytic combustion: When combustible gases such as LPG diffuse onto the surface of the detection element, flameless catalytic combustion (oxidation reaction) occurs under the action of a catalyst.
3. Heat and resistance changes: The heat generated by combustion further raises the temperature of the detection element (D), resulting in an increase in the resistance value of its platinum wire. The resistance of the compensating element (C) remains unchanged as it does not participate in the reaction.
4. Bridge imbalance generates signals: The balance of the bridge is disrupted, generating a millivolt-level voltage difference signal that is linearly proportional to the gas concentration.
5. Signal Processing and Alarm: This weak signal is amplified and processed, and ultimately displayed as %LEL (percentage of Lower explosive limit). Usually, low alarms (20-25%LEL) and high alarms (50%LEL) are set. Once the limits are exceeded, an alarm will be triggered immediately.
Combustible gas alarms should be installed in places such as the liquefied petroleum gas storage tank area, compressed natural gas storage cylinder room (shed), liquefied petroleum gas or natural gas pump and compressor room (shed) within gas filling stations and combined gas filling stations. The LPG liquefied petroleum gas alarm is a gas concentration detection instrument used to detect the flammability of LPG liquefied petroleum gas. It sets the detection range based on the lower explosive limit of LPG liquefied petroleum gas and uses smart gas sensors for concentration detection. Ensure personal and property safety in industrial production.