Regarding toxic or flammable gas detectors

Old projects or new projects? Is it possible that the detector for the old project has expired? After a new project is completed, a sample gas is used for calibration; it’s quite sensitive. In any case, it’s essential to have this, otherwise the fire safety and civil defense inspections won’t be approved. If this is just for display, it will be a problem if an accident occurs. . I’m not sure if old factories are just for show; anyway, the new factory has just been completed, so it’s definitely going to be functional. .

When performing acceptance testing after installation, sample gas is used for detection; it is essential that the system responds sensitively.

These types of chemical sensors, let me take a look – they’re nothing but toys. 1. Every type of combustible gas causes changes in the sensor’s output; there’s no specificity or selectivity. 2. In short, it’s just a waste of time

3. For a single type of sensor, if it’s calibrated using methane, it’s called a methane alarm; if it’s calibrated using carbon monoxide, it’s called a carbon monoxide alarm. I guess if it’s calibrated using fart gas, it could be called a fart alarm. But how can the concentration of such gas be the same as that of the actual mixed gas? Bro, looking at this thing, it’s just some random numbers that are set up to deceive people by giving fake alarm reports. As for whether those reports are accurate or not, who the hell knows?

I just wanted to say upstairs that newly installed devices are definitely effective; otherwise, why would companies have to spend money on devices that don’t work? But after some time, they really stop working, especially in environments with severe corrosion – in such cases, many of these devices fail to function. As for gas detectors for flammable gases that are heavier than air, the requirements are much stricter; there’s no way such devices could fail to work, and inspections are also more thorough, as safety is of utmost importance. In our company, we use gas detectors to monitor hydrogen and HCL gases; it’s just a light, and replacing it would be too expensive, so it’s left there as a mere decoration. HCL gas has a strong odor that can be detected on site. Personally, I think it’s better to install proper detectors, as people can’t stay at the site for long periods and need to conduct inspections regularly; one should choose a solution that suits the actual conditions of the company

Flame detectors and toxic gas detectors are definitely effective; I worked on calibrating gas detectors for some time, so I know this well. The situation described by the poster might be related to a carbon monoxide detector; such detectors take longer to calibrate using low-concentration calibration gases, and this is a normal phenomenon. But for other gases, their specificity and response time are satisfactory. As for zero drift, it’s a normal phenomenon. According to the analysis tables, drift will definitely occur after long-term use; there are regulations regarding this, and regular calibration is sufficient. Additionally, the price of such imported instruments is more than twice that of domestic ones. At first use, there isn’t much difference between them; the main difference lies in stability – imported instruments may show little drift over five or six years, while domestic ones typically experience a deviation of at least a dozen percentage points within one or two years. Finally, there is a phenomenon associated with gas detectors: gas poisoning, where high concentrations of the gas being monitored cause damage to the detector’s chemical sensors, similar to how an overpressure diaphragm in a pressure transducer can rupture. Therefore, it is necessary to calibrate the detector using standard gases. The concentration of these standard gases is quite low; for example, in the case of gas detectors designed to detect combustible gases, a standard gas used for calibrating the 100% range has a methane concentration of 5%. For other toxic gases, the concentration is even on the order of ppm. There was once a site where a lighter was used to test for flammable gases… The sensor got damaged as a result of exposure to the gas, and the people on site were very angry, saying, \"What kind of thing is this? It works for a moment and then stops working… How can this be explained?\" What do you think?

It will definitely be sensitive right after it’s installed; otherwise you wouldn’t be able to receive alerts from these detectors. Over time, they stop working, and in most cases the sensors need to be replaced

Also, if there is too much dust in the production area, it’s possible that the dust covers the sensor; as a result, it cannot be detected at first but can be detected later. The reason for this might be that the calibration gas removes the dust covering the sensor. In areas with high dust levels, a filter should be placed in front of the sensor.

This shall be designed, installed, and regularly calibrated in accordance with the standard \"Code for Design of Detection and Alarm Systems for Flammable and Toxic Gases in Petrochemical Industries\" GB50493-2009； 1. For combustible hydrocarbon gases, catalytic combustion type or infrared gas detectors can be used. When the air in the area of use contains substances such as sulfur, phosphorus, silicon, lead, and halogen compounds that can poison the catalytic combustion detection elements, a poison-resistant catalytic combustion detector should be employed ； 2. In environments with low oxygen levels or high corrosivity, infrared gas detectors are recommended ； 3. For hydrogen detection, catalytic combustion, electrochemical, thermal conduction, or semiconductor detectors can be used ； 4. For detecting single-component flammable gases, a heat conduction type detector is recommended ； 5. For hydrogen sulfide, chlorine gas, ammonia gas, acrylonitrile gas, and carbon monoxide gas, electrochemical or semiconductor detectors can be used ； 6. For vinyl chloride gas, semiconductor or photoionization type detectors can be used ； 7. For hydrogen cyanide gas, an electrochemical detector is recommended ； 8. For benzene gas, semiconductor or photoionization type detectors can be used ； For phosgene, electrochemical or infrared gas detectors can be used. I hope this can help you. The regulations require this, but as for which specific model to use, it depends on the on-site environmental conditions and the medium involved.

The key point is that, for example, in the case of hydrogen sulfide detection, the sample gas needs to be held at the new measurement port for a few minutes before a reaction occurs; otherwise, one has to leave. The lifespan is not something to discuss for now