What is a gas alarm?
As the name suggests, a gas alarm is a gas leak detection and alarm instrument. When flammable or toxic gas leaks in the industrial environment, when the gas alarm detects that the gas concentration reaches the critical point set by the explosion or poisoning alarm, the alarm will send an alarm signal to remind the work to take safety measures and drive the exhaust Wind, shut-off and spraying systems prevent explosion, fire and poisoning accidents, thus ensuring safe production.
Classification of gas alarms
1. It can be divided into fixed gas alarm and portable gas detector according to its own shape.
The industrial fixed gas alarm is composed of an alarm controller (commonly known as a host) and a detector (commonly known as a probe). The controller can be placed in the duty room and mainly controls each monitoring point. The detector is installed in a location where gas is easy to leak. The core component is a built-in gas sensor, which detects the concentration of gas in the air. The detector converts the gas concentration detected by the sensor into an electrical signal and transmits it to the controller through a cable. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the alarm controller, the alarm Alarm signal, and can start external devices such as solenoid valves and exhaust fans to automatically eliminate hidden dangers.
Generally, two parts are needed for purchase, and the two parts add up to form a complete system. The exception is that the factory has its own DCS or PLC system. It may only be necessary to purchase the probe. The probe is directly connected to its own DCS or PLC system (equivalent to our gas control alarm controller). At this time, we need to communicate with the technical staff. Confirm the signal mode required for DCS or PLC system connection. Generally, the commonly used switching value is 485 or 4-20ma, which can be customized.
The portable gas detector is hand-held, and the staff can carry it with them to detect the gas concentration in different places. The portable gas detector integrates a controller and a detector, and is compact and flexible. Compared with fixed gas alarms, the main difference is that portable gas detectors cannot be connected to other devices.
2. According to the detection gas, it can be divided into: combustible gas alarm, toxic gas alarm and composite gas alarm. The gas alarm uses different sensors to detect different gases. The composite gas alarm can detect combustible and toxic gases at the same time.
When purchasing products:
1. It is necessary to determine the type of gas detected by the detector. For the same function, the detector model and appearance are the same. The sensor that is equipped with the gas is the one that detects the gas. The product nameplate will be marked.
The detector can detect the following gases: (all detect a single gas, one-to-one sensor, what gas sensor is selected for detecting what gas)
Natural gas (methane), liquefied petroleum gas (propane), artificial gas (carbon monoxide), carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide, sulfur dioxide, hydrogen sulfide, hydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen, ammonia, oxygen, lv gas, phosphine, cyanide, oxygen, ozone, toluene, acetylene, formaldehyde, ethylene, propylene, n-butene, isobutylene, acetone, methanol, ethanol, xylene, gasoline volatile gas, arsine, dioxide lv, Fluorine gas, COCl2 (light qi), silane and other compounds (gasoline, industrial solvents, paints, thinners, coolants, dry cleaning fluids, methyl acetate, etc.)
2. Need to determine the number of probes needed to facilitate the determination of the host model. Within 3 probes, a 1-3 bus system host is required, 4-9 probes are equipped with a 9 bus system host, and more than 10 probes need to use a 30 bus system. Host.
The difference between bus line controller
The host panel of the bus controller is displayed cyclically. It is easy to install and use, and is convenient for centralized management and control. It also saves installation materials. A two-core cable (twisted pair 2 * 1.0 or more) comes out from the host, and the probe is hung in series or parallel Too.
It is a probe that corresponds to a three-core signal line (3 * 0.5) to the host. The panel of the host is also displayed independently, and one probe corresponds to a display window.
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