Setting of carbon monoxide and ammonia alarm values
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Dear teachers: 1. What are the first-level and second-level alarm thresholds for carbon monoxide in toxic gas detectors? 2. What are the first-level and second-level alarm values for ammonia in toxic gas detectors? 3. Is the concentration unit for toxic gas detectors PPm or mg/m3? In accordance with Clause 5.5 of the \"Design Code for Detection and Alarm of Flammable and Toxic Gases in Petrochemical Industries\" (GBT50493-2019), the set value for the first-level alarm of toxic gases should be less than or equal to 100% OEL, while the set value for the second-level alarm should be less than or equal to 200% OEL. The OEL values for carbon monoxide and ammonia include PC-TWA/PC-STEL, which are both 20 mg/m3 and 30 mg/m3 respectively ； So, should we choose 20 or 30? Thank you to all the teachers for their guidance.
We set the carbon monoxide alarm threshold at 20 ppm, and the ammonia threshold at 25 ppm