Setting of the alarm threshold for formaldehyde gas detectors
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May I ask what are the typical alarm levels in ppm for grade 1 and grade 2 formaldehyde toxic gas detectors? What should be the measurement range of a detector?
According to GB50493-2009, the measurement range for toxic gases should be 0–300% of the maximum allowable concentration or 0–300% of the short-term exposure limit. If the detector does not meet the requirements, the direct harmful concentration can be set at 0-30%. The alarm setpoint is generally 0–100% of the maximum allowable concentration or the permissible short-term exposure limit. The secondary alarm value must not exceed 10% of the direct harmful concentration. In China, the maximum allowable concentration of formaldehyde is 3 mg/m3, while the concentration that causes immediate harm is 20 ppm. You should check the relevant data and carry out the conversions yourself
The maximum allowable concentration of formaldehyde is 0.5, right? The IDLH seems to be 30, I think
I checked the data from the MSDS. . Since it isn’t specified in standard 50493, I also suggested to the questioner that they verify the relevant data again. . I wonder where your data comes from?
This post was last edited by z306905301 on 2020-6-20 at 10:58. According to GBZ2.1-2019, the MAC value for formaldehyde is 0.5 mg/m3, while the IDLH value in 50493 is 37 mg/m3.
According to GBT 50493-2019, the first-level alarm value for toxic and flammable toxic gases is 100% OEL, while the second-level alarm value is 200% OEL. The discussion suggests that the preferred order for selecting OEL values should be MAC > PC-TWA > PC-STEL. The MAC for formaldehyde is 0.5 mg/m3; based on the formula, the first-level alarm threshold is 0.4 ppm, and the second-level alarm threshold is 0.8 ppm.