Regarding toxic gas detectors: Setting of alarm values and high alarm values
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Are there any regulatory documents specifying that the setting for toxic gas detectors in tank areas should be 75% of the setting values used elsewhere? What file is it?
50493-2019 5.5.2
5.5.2 The setting of alarm values shall comply with the following provisions: 1 The first-level alarm setting for combustible gases shall be less than or equal to 25% LEL. 2 The secondary alarm setpoint for flammable gases shall be less than or equal to 50% LEL. 3 The first-level alarm setting for toxic gases should be less than or equal to 100% OEL, and the second-level alarm setting for toxic gases should be less than or equal to 200% OEL. When the measurement range of existing detectors is insufficient to meet the measurement requirements, the first-level alarm setting for toxic gases shall not exceed 5% IDLH, and the second-level alarm setting for toxic gases shall not exceed 10% IDLH. 4 The preset value for the oxygen peroxide alarm in the environment should be 23.5% VOL, while the preset value for the oxygen deficiency alarm in the environment should be 19.5% VOL. 5 For linear combustible gas measurement, the set value for the first-level alarm should be 1 LEL·m ； The set value for the secondary alarm should be 2LEL·m. You might not have understood my question. What I’m asking is whether there are any specific regulations regarding the toxic gases in the tank area. Our supervisor said he’s seen a document stating that the allowable levels of toxic gases in the tank area should be *75% of those in other areas. But I don’t know what this file is called anymore.
Everyone, I found it myself: Index > Other Industry Standards (HB) > AQ 3036-2010 Specifications for the Installation of On-site Safety Monitoring Equipment in Areas Handling Hazardous Chemicals > 4 Requirements for the Installation of Safety Monitoring Instruments in Tank Areas. 4.3.6 Toxic gas alarms should have at least two levels of alerting; the threshold for the first level of alerting should be 75% of the maximum allowable concentration. In cases where the maximum allowable concentration is low and the sensitivity of the existing monitoring and alarm instruments is not sufficient, the threshold for the first level of alerting can be increased appropriately, provided that this still allows for effective monitoring and alerting while preventing occupational poisoning； The second-level alarm value is 2 to 3 times the maximum allowable concentration.