The alarm is composed of detector and alarm control host. It is widely used in petrochemical industry with toxic gases such as petroleum, chemical industry and oil depot. It is used to detect the leakage of indoor and outdoor dangerous places, and is an important instrument to ensure production and personal safety. When all toxic gases in the measured field are present, the detector converts the gas signal into voltage signal or current signal and sends it to the alarm device, which displays the percentage concentration value of the lower explosive limit of toxic gases. When the concentration of toxic gas exceeds the alarm setting value, an audible and visual alarm speaker signal will be sent out, and the personnel on duty will take measures in time to avoid explosion accidents.Once the electronic alarm horn loudspeaker is fixed and installed in place, its position is not easy to change. The following points should be considered in specific applications.
(1) Find out the possible leakage point of the monitored equipment, analyze its leakage pressure, direction and other factors, and draw the probe location distribution map.
(2) Determine the leakage direction of toxic gas in case of large leakage according to the specific factors such as air flow direction and wind direction of the site.
(3) According to the density of the leakage gas (greater than or less than air), combined with the flow trend of air E gas, the three-dimensional flow trend chart of the leakage gas is synthesized, and an initial set point is made at the downstream of its flow.
(4) Study whether the leakage state of the leakage point is micro leakage or jet. In case of micro leakage, the set point shall be close to the leakage point. In case of jet leakage, it should be slightly away from the leakage point. On this basis, the finalized plan is formulated. In this way, the quantity and variety to be purchased can be estimated.
(5) For places with large leakage of toxic gas, a detection point shall be set every 10-20m according to relevant regulations. For unattended small discontinuous pump house, pay attention to the possibility of toxic gas leakage. In general, the detector should be installed at the lower air outlet.
(6) For places with hydrogen leakage, the detector shall be installed on the plane above the leakage point.
(7) For medium with gas density greater than air, the detector shall be installed on the lower plane below the leakage point, and pay attention to the characteristics of the surrounding environment. For places where toxic gas is easy to accumulate, special attention shall be paid to the setting of monitoring points.
(8) For the open toxic gas diffusion and escape environment, if there is no good ventilation conditions, it is easy to make the toxic gas content in the air of a place close to or reach the lower explosive limit concentration. These are monitoring points that cannot be ignored. According to the analysis results of on-site accidents, more than half of them are caused by incorrect installation and calibration. Therefore, correct PA loudspeaker installation and calibration precautions are introduced to reduce failures.