About gas detectors

1. Can a fixed combustible gas detector be made into a two-wire wiring method?
       No, the two-wire signal and power supply share one wire, and the maximum working current provided is 20ma, while the working current of the combustible gas sensor is 80ma, which cannot meet its normal working current.

       2. How is the effective detection range of a fixed gas detector defined?

       According to the "Petrochemical Enterprise Combustible Gas and Toxic Gas Detection Alarm Design Specification" (SH3063-1999):

       "3.0.8 The effective coverage horizontal plane radius of the combustible gas detector should be 7.5m indoors and 15m outdoors. One detector can be installed within the effective coverage area. The distance between the toxic gas detector and the release source should not be greater than 2m outdoors and should not be greater than 1m indoors."

       3.What are the regulations for the installation height of fixed gas detection alarms?

       According to the "Petrochemical Enterprise Combustible Gas and Toxic Gas Detection Alarm Design Specification" (SH3063-1999):

       “6.1.1 Detectors for detecting flammable or toxic gases heavier than air should be installed at a height of 0.3 to 0.6 m from the floor (or floor). 

       Note: Gases with a density greater than 0.97 kg/m3 (under standard conditions) are considered heavier than air; gases with a density less than 0.97 kg/m3 (under standard conditions) are considered lighter than air. 

　　6.1.2 The detectors for detecting flammable or toxic gases lighter than air should be installed 0.5 to 2 meters above the release source.

       4.What kind of standard gas is used to calibrate the combustible gas detector?

       According to the "Combustible Gas Detection Alarm" (JJG693-2004):

       “5.1.2.1 The gas standard material shall be the same as the gas being measured. For general instruments, isobutane or propane gas standard materials may be used.”

       The company uses isobutane for calibration.

       5.What is the principle of catalytic combustion detection?

       The principle of catalytic combustion is to prepare a high-temperature resistant catalyst layer on the surface of the platinum resistor. At a certain temperature, the combustible gas catalytically burns on its surface. The combustion causes the temperature of the platinum resistor to rise and the resistance to change. The change value is a function of the concentration of the combustible gas.

       6.What does FS stand for?

       FS is the abbreviation of full scale, which indicates the size of the measuring range.

       7.What types of display screens are currently on the market and what are their respective characteristics?

       Currently on the market there are light emitting diodes (LED), liquid crystal displays (LCD) and organic light emitting displays (OLED)

       8.What gases can be detected by the gas detector based on PID photoionization detection principle?

        Photoionization gas sensor (PID) is the most convenient and sensitive detection method for detecting volatile organic compounds (VOCs). Especially for gas leaks with very low concentrations, it has unparalleled advantages over other types of sensors. In general, photoionization gas sensor (PID) is mainly used for the detection of volatile organic compounds (VOCs), which include:  

       Aromatics: benzene, xylene, naphthalene, etc.;  

       Saturated and unsaturated hydrocarbons: octane, ethylene, cyclohexane, etc.;

       Ketones, aldehydes, ethers: acetone, propionaldehyde, propyl methyl ether, etc.; 

       Halogenated hydrocarbons, thiohydrocarbons, alcohols, esters, hydrazines, etc. 

       In addition, detectable inorganic substances include: arsenic and ammonia.

       9. What do the letters in the explosion-proof grade ExdⅡCT6 mean?

       Ex explosion-proof public mark  d Flameproof type (electrical equipment with flameproof enclosure) Class II: electrical equipment for all other explosive gas environments except coal mines and underground. C: refers to the ignition energy uJ, 280, >180, 60...80, <60. T6: refers to the temperature group, T6 is 85 degrees.

       10.What is the role of pretreatment of online gas detectors?

       Online gas analyzers should be used in sites with complex working conditions. The moisture, dust, and high temperature of the sample gas will have various effects on the instrument's detection. Through the pretreatment system, the sample gas can be sampled, kept warm, degreased, dusted, condensed, dehydrated, pressurized or depressurized, constant flow, and constant pressure, and then the dry, clean, and constant sample gas can be sent to the gas analyzer for detection to ensure the accuracy and stability of the measured value.

       11. What are the principles of online oxygen detectors for detection?

       Zirconia, electrochemistry, paramagnetism, laser

       12. Why must the composition of background gas in the industrial and mining survey form be filled in in detail?

        Online gas detectors should be used more in sites with complex working conditions. Different gases may cause cross-interference or even corrosion. By filling in the background gas in detail, factors such as instrument selection, interference, and corrosion can be fully considered during the analyzer design phase to ensure the stability and accuracy of the instrument after it is put into use.

       13.What role does the vortex condenser play in pretreatment?

       Reduce the moisture content in the sample gas

       14. In what cases is it necessary to use a pressure reducing valve in the pretreatment of an online gas detector? In what cases is it necessary to use a suction pump?

       When the sample gas pressure in the pipeline is greater than 0.2MPa, a pressure reducing valve should be used. When the pressure is less than 50KPa, a suction pump should be used.

       15. What are the steps for dust removal in the pretreatment of online gas detectors?

       Generally, there are three levels of filtration: sampling probe filtration, pre-treatment filter, and analytical instrument fine filtration. The specific configuration depends on the actual working conditions.