Newbie seeking help: several questions regarding gas detectors

You think it’s a coincidence? I’m the manufacturer; message me privately: lol

1. Wuxi GreenTong, Shanghai Ennix.

2. There are specific requirements; you can check the relevant standards. For toxic and harmful gases, it should be within 1.5 meters of the emission point. I’m not quite sure about the exact details. 3. The central control room can be integrated directly; it is possible to connect secondary meters to it, or to connect it directly to the DCS system. 4 falls under mandatory calibration, and in high-risk industries, this process generally takes between 3 months and half a year. 5. CO is just CO. The combustible gas detector cannot detect the CO level. 6. Electrochemical probes generally need to be replaced every one and a half to two years. 7. Do you need measurements on-site or in a portable manner? For fixed on-site measurements, it is not recommended to use multi-functional models.

1. Which domestic manufacturers offer relatively good quality? How is Shenzhen Te’an? Answer: Hangzhou Juguang, Shenzhen Te’an, and others are all good. 2. What are the requirements for the installation location of gas detectors? Was it required in the last test to be installed within one meter of the release point? Are there any explicit regulations on this matter? Answer: There are specific instrument specifications that the poster needs to consult. 3. When installing gas detectors, should they be connected to a control and alarm unit or routed to the control room? Some of these detectors support 4–20mA signals as well as the HART protocol, while others can only be used in conjunction with a dedicated control and alarm device. Which approach is generally used? Answer: For those with a low number of points, it is recommended to use a dedicated alarm; for dozens or more, FGS should be considered. Try to avoid entering the DCS; it does not meet safety requirements. 4. Do gas detectors fall under the category of devices requiring mandatory calibration? Is it necessary for a statutory authority to conduct regular verification and issue a verification certificate? Answer: It falls under mandatory inspection, and a certificate is required. Here, I almost have to check this certificate during every safety inspection; it is generally inspected once a year. Normally, one can take the gas cylinder themselves to test whether it is in good condition. 5. Does CO fall under the category of flammable gases, or under the category of toxic and harmful substances? Is it appropriate to use a combustible gas detector? What about the benzenes in the tar irrigation areas? Are they toxic and harmful, or are they flammable and explosive? Answer: CO is classified as toxic, benzene is also toxic, but other benzene derivatives such as toluene are classified as flammable. 6. As for the type of sensor, what is commonly used? Is it electrochemical, catalytic combustion, or semiconductor? What are their respective advantages and disadvantages? Answer: Generally, combustible materials use catalytic combustion; toxic ones use electrochemical methods; I have no experience with semiconductors. 7. Regarding the conditions in my factory, exhaust gases typically contain CO, hydrogen, hydrogen sulfide, sulfur dioxide, etc. Can a multi-functional detector be used for testing them? What types of detectors are generally installed in tar irrigation areas? If flammable gases are purchased, is it still necessary to test for benzene? Answer: It’s better to measure them separately; the safety level is higher in that case. Tar is generally flammable, as for benzene compounds, it depends on the specific type; it’s difficult to tell for sure as no information was found. Information can be obtained from the local metrology and testing institute.

The analysis is very comprehensive; basically all the issues related to this topic are addressed in this post. There are many brands available, so take a look at them. There are specific requirements regarding the installation height as well, so be sure to determine those properly, otherwise it will be troublesome to start over.

Thank you so much! ! There is indeed a lack of knowledge in this area; I never paid attention to it before

Catalytic combustion type sensors are relatively cheaper than semiconductor ones; the probes generally need to be replaced every three years. To measure CO and hydrogen, the sensor should be placed above the source of emission, while for measuring sulfur dioxide, the alarm device should be positioned at a height of 50 cm above the ground

3. When installing gas detectors, should they be connected to a control and alarm unit or routed to the control room? Some of these detectors support 4–20mA signals as well as the HART protocol, while others can only be used in conjunction with a dedicated control and alarm device. Which approach is generally used? For newly installed systems, it is recommended to use a separate PLC and not to combine it with a DCS; refer to Document No. 116 from the Safety Supervision Department (2014). 7. Regarding the conditions in my factory, exhaust gases typically contain CO, hydrogen, hydrogen sulfide, sulfur dioxide, etc. Can a multi-functional detector be used for testing them? Fixed probes use a single point. Gas probes are used to detect gas leaks; for mixed gases, if the concentration of one component exceeds the specified limit, it indicates that there is a leak in that mixed gas. H2S is a toxic gas; it should be measured at the PPM level. @jiaguoyun

1. Which domestic manufacturers offer relatively good quality? How is Shenzhen Te’an? Shenzhen Nanyou Nuoan, Beijing Yanshan. 2. What are the requirements for the installation location of gas detectors? Was it required in the last test to be installed within one meter of the release point? Are there any explicit regulations on this matter? There is no requirement for a distance of one meter; anyway, we’re not within that distance at the site. The specified height range is 300–500 mm – too low and water ingress can occur, while too high reduces the effectiveness. 3. When installing gas detectors, should they be connected to a control and alarm unit or routed to the control room? Some of these detectors support 4–20mA signals as well as the HART protocol, while others can only be used in conjunction with dedicated control and alarm devices. Which method do people usually use? The fire protection requirements dictate that an on-site alarm device be installed on each gauge, and that a zone alarm system be available for each area; these signals are then fed into the DCS, from where interlocks are activated to trigger alarms. The functions of the DCS are sufficient, and in my opinion, there is no need for a separate gas detection system. 4. Do gas detectors fall under the category of devices requiring mandatory calibration? Is it necessary for a statutory authority to conduct regular verification and issue a verification certificate? It falls under the category of substances subject to mandatory inspection, requiring an inspection once a year; one should turn to a provincial-level metrology inspection institute with the appropriate qualifications for such inspections. 5. Does CO fall into the category of flammable gases, or rather in the category of toxic and harmful substances? Is it appropriate to use a combustible gas detector? What about the benzenes in the tar irrigation areas? Are they toxic and harmful, or are they flammable and explosive? There are specialized analyzers for benzene; CO is likely flammable, and the toxic substance referred to here is hydrogen sulfide. 6. As for the type of sensor, what kind is generally used – electrochemical, catalytic combustion, or semiconductor? What are their respective advantages and disadvantages? Electrochemistry and catalytic combustion: 7. For the conditions in my factory, exhaust gases contain CO, hydrogen, hydrogen sulfide, sulfur dioxide, etc. Can a multi-functional detector be used for detecting these substances? What types of detectors are generally installed in tar irrigation areas? If flammable gases are purchased, is it still necessary to test for benzene? As long as it is a qualified multi-functional product, that’s fine; benzene requires a separate gauge for measuring it, and such gauges are quite expensive