Common detectors for combustible and toxic multi-medium release sources?

This post was last edited by Xiao Fufu on 2024-6-24 at 14:09. For a single release source, can multiple media share the same catalytic combustion detector? Answer: No, you cannot. Catalytic combustion detectors are typically designed for a single type or a specific range of combustible gases. Their operating principle is based on the thermal effects of catalytic combustion; they detect the concentration of combustible gases by measuring changes in the resistance of a platinum wire. Since different flammable gases produce varying amounts of heat when burned, it is difficult for a catalytic combustion detector to accurately detect multiple flammable gases simultaneously. Basis: When used to detect combustible gases, catalytic combustion sensors primarily rely on the flameless combustion of these gases on the surface of the sensor element’s carrier under the action of a catalyst. This results in an increase in the temperature of the carrier, which in turn causes a change in the resistance of the platinum wire. This principle determines its applicability to specific flammable gases or ranges of gases. For a toxic emission source, can multiple media share the same electrochemical (infrared, photoionization) detector? Answer: It depends. For electrochemical detectors, they detect gases through chemical reactions on the surface of the sensor electrode. In theory, they can detect various toxic gases; however, it is necessary to consider the compatibility and selectivity of different gases in their reactions at the electrode. Infrared and photoionization detectors generally have a broader capability for gas detection; however, the spectral absorption and ionization characteristics of gases also need to be taken into account. Basis: Electrochemical sensors come in two types: two-electrode and three-electrode. The target gas undergoes a reaction at the sensing electrode, and the resulting current is proportional to the gas concentration. However, in cases where multiple toxic gases are present, if the reactions of various gases on the electrodes interfere with or overlap each other, it may be necessary to install separate detectors. In design institutes, is it generally acceptable to install just one detector for flammable substances, while for toxic substances, a detector should be installed for each type of medium? Answer: Yes. When designing and installing gas detectors, design institutes generally follow certain codes and standards. For flammable gases, due to their flammability and explosiveness, a separate detector is typically installed for each emission source, so as to ensure the accuracy and reliability of detection. For toxic gases, since the degree of harm to the human body and the detection requirements may vary depending on the type of toxic gas, separate detectors are usually installed for each type of gas. Basis: For single-component gas media that are both combustible and toxic gases, toxic gas detectors shall be installed ； In a multi-component gas mixture where combustible gases and toxic gases are present simultaneously, combustible gas detectors and toxic gas detectors should be installed separately. This indicates that when designing and installing gas detectors, it is necessary to consider the type and characteristics of the gas, as well as the requirements for detection and alarm.

If flammable gases are of the same type and their interference with the detector is negligible, the same catalytic combustion detector can be used. However, if there is interference between multiple media, or if the ignition points and lower explosive limits of different media vary, it is generally recommended to use separate detectors. For toxic gases, since the detection principles and sensitivities may vary among different gases, it is generally recommended to use specialized electrochemical, infrared, or photoionization detectors for each type of toxic medium. This ensures that the concentration of specific toxic gases is accurately monitored. Typically, the standard practice in design institutes is, out of safety considerations, to install separate detectors for each type of potential harmful gas, so as to ensure the accuracy and timeliness of detection. The criteria for selecting and configuring detectors typically include: gas type, potential hazards, environmental conditions, interfering factors, etc. .

Thank you for your reply~ Based on your response, I understand that for flammable and toxic substances, separate detectors should be installed for each type of medium. However, after analyzing the mixture of gases present at the site as well as the types of detectors chosen, is it possible that multiple media could share the same detector? So, is the analysis and judgment generally carried out by the manufacturers of flammable and toxic gas detectors? What documents do I need to provide to them?

It’s sufficient to provide the names of the flammable and toxic gases present on site