One: Why should the boiler room be installed with an industrial explosion-proof gas leak alarm? The gas boiler includes two systems of a gas burning device and a boiler body. Gas-fired equipment mainly refers to furnaces and burners, as well as other equipment related to the combustion process. Its main function is to pass a certain amount of combustible gas and air into the combustion equipment, and convert the chemical energy into heat energy through the combustion of combustible gas. To provide continuous heat to the boiler body. The boiler body converts water into water vapor by means of thermal energy provided by the combustion equipment, making it a certain amount and quality (pressure and humidity) of steam. The whole boiler production process is to send a certain amount of combustible gas and a corresponding amount of air into the furnace, and the heat generated by the combustion is transferred to the water, so that the water vaporizes under constant pressure to form water vapor of a certain pressure and temperature. Due to the large gas pipelines of gas boilers, the consumption of flammable gases is large, and some pipelines have been aging and corroded. If the pipelines are not maintained and repaired, flammable gas leakage is likely to occur during the gas transmission process, resulting in accidents. As a process equipment for generating heat energy and power, gas boilers are widely used in industrial sectors such as electric power, machinery, chemicals, textile and paper, and heating and heating in hotels and residential areas. Due to the need for heating and heating in northern cities in China, the number of boilers in use is larger. It is also necessary to install industrial explosion-proof gas detection alarms to ensure safety. Gas-fired boilers have gradually entered people's lives. The fuel for a gas boiler is a combustible gas, mainly natural gas or gas. The main components of natural gas and gas are methane, and some simple alkanes are also mixed. These components are highly flammable and explosive gases. The lower limit of natural gas is 4%, and the lower limit of gas accident is 6.2%. It is extremely easy in air. have an accident. The gas detection alarm made by the principle that the physical and chemical properties of the substance are changed by the action of the gas can be detected by the boiler furnace nei flammable gas leak detection and concentration measurement. The gas alarm is made of catalytic combustion sensor material with high sensitivity and fast response time. The gas sensor senses the leakage of the combustible gas and immediately gives an alarm, and can also link the external exhaust fan, shut-off valve, fire sprinkler and other external equipment. These can be used as initial preventive measures for boiler fires. With the development of science and technology, more high-tech such as artificial intelligence will be applied to the prevention of gas boiler accidents. Second: gas leakage in gas boiler room and its cause analysis Natural gas leakage in gas boiler rooms is mainly caused by the illegal operation of employees and natural and external forces, mainly for the following reasons. 1, room nei, external gas pipeline leakage: construction quality is not closed during construction, or long-term operation pipeline corrosion. 2. Boiler body leakage: due to the failure to comply with relevant technical requirements during the initial design or installation of the gas boiler. For example, the welding of the boiler mode wall is not strict; the furnace is not baked according to the relevant technical requirements after the construction, or the boiler lifting temperature is too fast. The cracking and sealing of the brick wall is not strict; the vibration of the gas boiler is large during operation, the weld seam is desoldered or the furnace wall is caused. The insulation layer is cracked; the fire hole, explosion-proof door, manhole door, etc. are not closed tightly; the boiler is automatically turned off during operation. 3, burner leakage: design reasons or installation and commissioning is not in place; after long-term operation of the burner, the air-fuel ratio is out of adjustment, so that the combustion conditions change. 4. Control, adjustment, measurement and other parts and their connection parts leak: due to the frequent movement of these parts, the switch may be inflexible, the closure is not strict, or the connection part is loose due to vibration during the operation of the boiler, or the gas is leaked, or due to control The quality of parts such as adjustment and measurement is poor, and the air leakage is not tightly closed; or leakage due to aging of flanges, gaskets, sealants, etc. Three: When the boiler room nei natural gas is seriously leaked, the following phenomenon will occur: 1. The working pressure of natural gas has changed. 2. A strong airflow can be heard near the source of the leak. 3. The hand-held alarm device worn by the on-site staff member will give an abnormal alarm sound. 4. When the leakage is large (the concentration is high, reaching the set low report of 25% or the high report is 50%), the fixed alarm will automatically alarm and automatically open the exhaust fan. 5. In serious cases, accidents such as boiler body or natural gas pipeline accidents, fires, etc. will occur. Four: The importance and necessity of installing industrial explosion-proof flammable gas alarm system The boiler room nei with natural gas as fuel must be equipped with flammable gas alarm and linkage emergency shut-off valve. According to GB 50041-2008 boiler room design specification, flammable gas alarm should be set. When there is an olefinic gas in the air or a flammable flammable gas volatilized, the detector detection signal is immediately transmitted to the alarm control unit through the cable, and the controller displays the gas concentration. When the set alarm concentration value is exceeded, the alarm controller That is to say, the sound and light alarm signals are output and the linkage control signals are output, and the equipment such as the fan is controlled to eliminate the dangerous situation, thereby ensuring the safe production of the factory and avoiding accidents. It is recommended to use the CRGD-1 industrial explosion-proof wall-mounted flammable gas alarm produced by Nedley in the boiler room to detect natural gas leakage. The importance of installing a natural gas alarm in the boiler room. The main component of natural gas is methane, which is a flammable and explosive gas. If a natural gas leak encounters an open fire, static electricity, lightning, or improper operation, an accident or fire may occur, and in a confined space, people may be deprived of oxygen, suffocation, or even death. The installation of natural gas alarms can effectively prevent accidents and fires, thus avoiding the safety of property and workers. The importance of installing a natural gas alarm in the boiler room. The role of the natural gas alarm is to detect the concentration of natural gas leakage. Once the standard exceeds the standard, an alarm is issued to remind the staff to take safety measures. From its role we can easily see the importance of gas alarms. If a gas alarm is installed, if we forget to turn off the gas source, once the natural gas concentration reaches the alarm value we set, the alarm will remind us that there is a gas leak, and measures should be taken to avoid accidents to a large extent. occur. The importance of installing a natural gas alarm in the boiler room. To ensure the reliability of the product performance, we recommend that the user maintain and calibrate the product regularly using the gas gas alarm period nei. If you have any questions, please ask a professional technician for advice. The natural gas accident is a high-temperature combustion process (a thousandth of a second) that produces high temperature (up to 3000 ° C), and the wave speed can reach 300m / s, causing great destructive power. If a natural gas leak encounters an open fire, static electricity, lightning, or improper operation, an accident or fire may occur. In a confined space, people may be deprived of oxygen, suffocation, or even death, causing incalculable losses to the unit’s safe production and the state and people’s lives and property. . According to the site survey and the discussion of the personnel of the relevant departments, it is necessary to ensure the safety of the gas, and the following schemes should be formulated without affecting the production: install the leaky points at the inlet valve and the burner at the gas boiler room nei Gas detection alarms are very necessary to monitor the leakage point of natural gas and the concentration of concentrated gas in time, to prevent early warning of safety accidents, to issue alarm signals, or to activate a chain protection system to minimize accident losses. Safety is life, safety is responsibility, safety is efficiency! V. Basic structure and working principle of explosion-proof natural gas monitoring and alarm control system The gas detection alarm is mainly composed of four parts: 1. Combustible gas detector: Real-time monitoring of the leakage point and the concentration of natural gas accumulated in the environment, because the main component of natural gas is methane (CH4), its specific gravity is lighter than air, and it will go upward when a leak occurs, so the flammable gas detector Installed on the gas release source or above the leaking point, in order to detect the leakage of natural gas in a timely and accurate manner, and sound and light alarm when the gas leakage concentration reaches the low limit alarm, reminding the staff to check the repair in time, after detecting When the gas leakage concentration reaches the high limit alarm, a control signal is sent to the automatic shut-off valve, and the air source is cut off, and an emergency sound and light alarm is also issued to prompt the staff to take measures. 2, monitoring alarm control system: centralized real-time monitoring of all leaks detection and gas leakage or concentration of concentration, when the alarm set value is reached, sound and light alarms, and reserved interfaces with other fire protection systems. Installed in a manned duty room to monitor natural gas leaks and alarms in real time and in time to ensure production safety. 3. Automatic gas shut-off valve: The gas leakage detected by the flammable gas detector. When the high and low alarm limits are reached, the alarm controller will send a signal to the gas shut-off valve and automatically shut off to cut off the gas source. At the same time, it will also send a signal to the on-site exhaust fan equipment to make the exhaust air run automatically. 4. Connection part: refers to the anti-electromagnetic interference armored cable or the metal casing cable, which transmits the signal of the gas detector to the monitoring alarm control system. When the gas detector detects the combustible gas in the air, the gas concentration is converted into a corresponding 4-20ma current signal or RS485 digital signal, which is transmitted from the connecting cable to the monitoring alarm control system, and the monitoring alarm controller is in the electrical signal. It is converted into a digital signal, and the concentration value of the gas is displayed on the liquid crystal display. When the detected value is greater than the alarm set value, an alarm signal is issued by the buzzer or the warning light, prompting the worker to pay attention, and promptly repairing the cause and eliminating the fault. Or start a chain emergency system. Sixth, the installation location and quantity analysis of flammable gas detectors (see CAD drawing for details) According to the requirements of the security department and the actual survey of the production site, the initial layout of the gas detector (see CAD drawing) and the installation method are as follows: First, consider the size of the area to be inspected (installation location). The radius of the natural gas alarm (probe) provided by our company is 7.5 meters, and the distance between each probe must not exceed 15 meters. Secondly, consider the specific structure of the nei part of the gas boiler room. After the external gas pipeline enters the room, it will be connected to the boiler's burner for ventilation. Therefore, when installing the probe, it is necessary to arrange the point at the high point or above the intake main valve or the burner. Finally consider the source of natural gas leakage. Natural gas leaks exist in natural gas pipeline junctions and pipeline valves. Natural gas pipeline junctions are not well sealed or long-term cracks can cause natural gas leakage. The place where the pipeline valves are prone to improper operation causes gas leakage, so these two are the main gas leakage sources in the boiler room. According to the above three steps, the optional position of the natural gas alarm is finally determined: it is installed at the position of the natural gas pipeline branch and the pipeline valve (the natural gas is lighter) 1.5 meters (specifically, it is installed according to the site conditions and does not affect the work). If the boiler has just a wall to the left and right, it can be installed directly on the wall. The optional height should not be too high or too low. The installation is too high, and the natural gas diffuses around the web during the process of diffusion. The amount of natural gas reaching the detector is reduced, resulting in inaccurate test data. The installation is too low, the natural gas is light and rapid, and when the detector has not fully induced the natural gas, the natural gas has already floated above the detector, which will also cause the detection data to be inaccurate. The specific installation location needs to be determined according to the site conditions. The boiler room area is 100 square meters, then according to GB 15322.1-2003 combustible gas detector part 1: the point type flammable gas detector with measuring range of 0-100% LEL, each alarm covers an area of ​​25-30 square meters. So the number of installations is about three. Then one of the supporting controllers is connected by bus 485 output. The specific installation quantity can be calculated by referring to the detector detection area. VII. Connection line specification between flammable gas detector and controller: 1. If the installation quantity is between 1-2 sets, it is recommended to use 3X1 square RVVP cable signal shielding line, as shown in the figure: 2. If the number is more than 2, it is recommended to use 4X1 square RVVP cable signal shielding line, as shown in the figure: Eight, flammable gas detector in the operation and management of the precautions 1. Misunderstanding of the alarm of the alarm Many people think that as long as there is flammable gas or toxic gas in the vicinity of the detector, the controller should give an alarm signal, and the alarm may be malfunctioned without warning. This kind of understanding is wrong. The detection object of the alarm is flammable gas in the air, such as flammable gas: the monitoring range is 0-100% LEL, but only when the flammable gas concentration reaches the alarm set value (for example, the alarm low-report value is set to 25% LEL) The alarm signal is sent out, and there is no flammable gas to alarm. 2. The gas detector's own explosion-proof facilities are damaged and have not attracted enough attention. In use, there is a phenomenon that the explosion-proof facilities such as damaged, loose, and ruptured explosion-proof pipes are damaged and nobody cares. As we all know, the installation location of the alarm is a flammable and explosive place. In particular, the detector is directly in contact with the flammable gas on the site. If the explosion-proof facility is damaged and not repaired or updated in time, when the concentration of flammable gas reaches the minimum alarm limit, it may be Directly causing fire, not only does not play a role in disaster prevention, but also become a source of fire. 3. There is no corresponding gas detector distribution map in the control system. During use, the controller operates the distribution map of the combustible gas detector on the cabinet. When there is an alarm, the position of the corresponding combustible gas detector and the position of the release source cannot be confirmed in time and accurately. Because there is more than one gas detector throughout the monitoring area, each gas detector has its own monitoring area and detection range. Each gas detector has a corresponding alarm display on the control system. In order to facilitate accurate and timely determination of the position of the release source, the gas detector profile should be present in the control system. 4. Feel free to change the position of the gas detector During the modification of the production device, the position of the gas detector is arbitrarily changed, resulting in a decrease in the sensitivity of the gas detector or a detection dead angle in the device nei. The determination of the detection points is determined according to relevant aspects of the process equipment, equipment facilities, gas accumulation and the like. In the process of reconstruction and expansion, regardless of the function and detection range of the gas detector, changing the position of the gas detector at will inevitably results in a place where the detection position is repeated or not detected. Moreover, during the disassembly process, the sensitivity of the gas detector may be lowered due to vibration or the like. 5, the inspection is not in place In actual use, it is not that the inspection is not comprehensive or that the inspection cycle is too long, which causes the alarm management to be disconnected. According to the "Code of Practice for Combustible Gas Detection Alarms", the flammable gas detection alarm should be inspected regularly. Check the nei capacity: check the operation of the system; perform a visual inspection once a week, check the connection parts, moving parts, display and control knobs, check the fault lights, check the explosion-proof seals and fasteners, check the probe for blockage, Check the waterproof condition and other nei capacity. 6, the test method is improper When testing the reliability of the gas detection alarm, such as a flammable gas detector, the liquefied gas directly used by the lighter is in contact with the sensor, thereby causing damage to the gas sensor, and the sensitivity of the detector is lowered or malfunctions. 7, the file information is not complete. The gas alarm is not managed by a person, and the file information is incomplete. As an important safety equipment, gas detectors and alarm control systems should be managed by special personnel to establish and improve all basic materials. Strengthen maintenance and have relevant records. Nine, combustible gas alarm system components and technical specifications 1, combustible gas detector product description: CRND-1 point flammable gas detector is a new type of gas detection instrument produced by our company. This machine is made of high performance gas sensor and microcontroller technology, combined with excellent SMD process, with good repeatability and temperature and humidity. Features such as long life and easy operation, suitable for detecting gas concentration in industrial environments. The detector adopts a three-wire 4-20mA current signal or a four-wire RS485 bus output, which has the characteristics of long transmission distance and good anti-interference performance. The detector is widely used in petroleum, petrochemical industry refineries, chemical plants, metallurgy, communications, gas, paint booths, restaurants, gas stations, gas stations, sewage treatment, power industry and other gases that may produce harmful gases to the human body. Detection. (1), main features *The probe has high sensitivity, rapid response, long life and short polarization time. *4~20mA standard analog output\RS485 bus output *2 switching passive alarm contact outputs *Infrared remote control operation *With sound and light alarm * Flameproof design, suitable for hazardous areas in Zone 1 and Zone 2 (2), product standards The design, manufacture and verification of this product are subject to the following national standards: GB3836.1-2010 "baozha sexual environment Part 1: General requirements for equipment" GB3836.2-2010 "baozha sexual environment part 2: protected by flameproof enclosure "d" Equipments GB15322.1-2003 "Combustible gas detectors Part 1: flammable gas detectors with a measuring range of 0 to 100 % LEL" JJG693-2011 "Test procedures for flammable gas detection alarms" GB4208-2008 Grade (IP code)" GB/T13384-92 "Technical conditions for the application of mechanical and electrical products packaging" (3) Main technical indicators Sampling method: natural diffusion; Detection principle: catalytic combustion type; Detection range: 0-100% LEL; Working voltage: DC 24V ± 6V; Power consumption: ≤3W; Working mode: continuous testing; Range deviation: ≤ ± 3% LEL; Mode of operation: infrared remote control; Response time (t90): ≤ 30s; Working temperature: -40 ° C ~ 70 ° C; Working humidity: ≤95% RH (non-condensing); Explosion-proof method: explosion-proof type; Explosion-proof grade: Exd IIC T6 Gb; Protection level: IP65; Environmental pressure: 86kPa ~ 106kPa; Output signal: 4 ~ 20mA three-wire system; Explosion-proof connection thread: M20*1.5 (nei pipe thread); Use cable: ≥1.5 mm2×3 shielded cable (three-wire); The maximum distance between the detector and the host: ≤1000m; Sensor life: three years; Product size: 180 mm × 140 mm × 80 mm; Weight: about 1Kg. 2, gas alarm controller (1), product overview The CRNDL-M2 gas alarm controller can be combined with the company's CRNDL-1 and other gas detectors to form an industrial gas intelligent detection and control system for monitoring and monitoring the gas concentration of the industrial site. When there is a gas or liquid in the air volatilized, the detector generates an electrical signal proportional to the concentration of the gas to be measured in the air. The signal is transmitted to the controller, and the controller displays the measured gas concentration after being processed. When the measured gas concentration reaches or exceeds the set value, the controller emits an audible and visual alarm signal and outputs relevant control signals to activate the corresponding control device, thereby avoiding a major accident. The human-machine interface of this product adopts large-screen LCD display and advanced keyboard interactive operation. The Chinese and English interface has clear display and simple operation. Its unique software anti-interference technology realizes soft fault detection of machine faults, high reliability and easy maintenance. (2), main features: * Chinese and English language switching to meet the needs of different users *nei embedded microprocessor, with a wealth of software functions, complete transmitter signal sampling, data real-time calculation, system fault detection, power management, button scan, display drive, alarm display, alarm peripheral drive and other functions. * Both analog (4-20mA current output) and digital (RS485 output) detectors can be connected at the same time, and the capacity is huge. Flexible selection of multiple upload protocols * Can manage detectors that detect different gas types, different ranges, and different data units *6 passive relay contact output, linkage programmable (expandable to 8 channels), normally open and normally closed, convenient for control requirements. * Wall mounted installation, easy and convenient (3), technical parameters Operating voltage: AC176V ~ AC264V (50Hz ± 1%) Power consumption: ≤100W Operating environment: temperature -10 ° C ~ +50 ° C, humidity ≤ 95% RH Atmospheric pressure: 86~106KPa Protection level: IP44 Input signal: 4 channels 4-20mA analog input, 1 channel RS-485 MODBUS-RTU four-bus system input (32 detectors can be connected) Transmission distance: 1500m (2.5mm2) Detection gas type: %LEL, ppm, %VOL Alarm output: 4 sets of programmable relay outputs, freely open normally closed (capacity: 10A / 30V DC or 10A / 250VAC) Alarm setting: low limit alarm, high limit alarm Alarm fang type: sound and light alarm Alarm sound: >90dB Alarm record: 1500 alarm information Display: 192*64LCD LCD display in English Dimensions: length × width × thickness: 340mm × 240mm × 110mm Weight: about 3kg Installation method: wall hanging Factory configuration: host, key, certificate, manual X. Technical description of portable flammable gas detector: Portable flammable gas detector is also hand-held, can be carried on the staff, similar to patrol, rechargeable work, ready to boot detection, nei lithium battery charging, standby for about 24 hours, as shown: The portable appearance is three colors, black, blue, and yellow, and the delivery is random. Introduction of main technical parameters: main feature 1. High measurement accuracy ◆ The CRPNDL-A1 gas detector uses a high-speed CPU processor to quickly and accurately handle system tasks and ensure the reliability of the detector. ◆ Imported gas sensitive components, high precision, high reliability, fast response and recovery time, good gas selectivity and strong anti-interference ability. 2. Display is intuitive ◆ LCD liquid crystal display, real-time display of gas concentration ◆ Good earthquake resistance 3. Low power consumption ◆ Small size, light weight, low power consumption, easy to carry. ◆ High-performance lithium battery, long working time, charging protection and low voltage protection to ensure more reliable battery life and longer life. ◆ Quick warm-up and fast response time. Technical Parameters: ◆ Detection principle: flammable and explosive gas catalytic combustion imported sensor ◆ Detection gas: combustible gas ◆ Sampling method: natural diffusion ◆ Battery: lithium battery ◆ Nominal voltage: 3.6V capacity 1600mAh ◆ Standby working time: >8 hours (at normal temperature) flammable and explosive gas ◆ Measurement accuracy: ±5%F·S ◆ Response time: ≤30S ◆ Charging voltage: DC5V ◆ Working temperature: -40 ° C ~ 60 ° C ◆ Working humidity: ≤95%RH ◆ Alarm system: sound and light alarm, vibration ◆ Product size: 80*50*30(mm) ◆ Product weight: 0.3KG ◆ Alarm volume: ≥75dB
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