Technical requirements for regular testing of gas detection and alarm instruments in the work environment
The main technical requirements include the following:
1. Power on self-test function: The instrument should have an automatic self-test function when turned on, and the alarm component should also be equipped with a manual self-test function.
2. Effective detection distance: The effective detection distance of non-contact gas alarm instruments shall not be less than 20 meters.
3、Alarm value setting: The standard specifies specific alarm value settings for different gases.
For example, the oxygen deficiency alarm setting value is 19.5% VOL, and the oxygen enrichment alarm setting value is 23.5% VOL (refer to GB 8958-2006 "Operating Procedures for Oxygen Deficiency Hazardous Operations" and GB 30871-2022 "Special Operation Specifications for Hazardous Chemical Enterprises");
The first level alarm setting value for combustible gases shall not exceed 25% LEL, and the second level alarm setting value shall not exceed 50% LEL;
The first and second level alarm settings for toxic and harmful gases are determined based on OEL (occupational exposure limit) or IDLH (concentration immediately threatening life and health);
4Error and repeatability: The standard provides clear requirements for the indication error, drift, and repeatability of the instrument. For example, the indication errors of combustible gases, toxic and harmful gases, and oxygen should not exceed ± 5% FS, ± 5% FS, and ± 2% FS, respectively, within the normal testing range of the instrument's full range;
5、Calibration and Interface: The instrument should be easy to calibrate and equipped with calibration programs and corresponding interfaces to ensure the accuracy of its measurement results;
6、Explosion proof performance: Instruments used in explosive environments should have explosion-proof performance in accordance with relevant regulations and obtain explosion-proof certificates;
7、Sound and light alarm device: The sound and light alarm device of the alarm should meet the visibility and sound pressure level requirements under specific conditions, ensuring that it can effectively alert staff in emergency situations;
8、Output control function: Instruments with output control function should be able to activate the output control function when an alarm signal is issued, such as cutting off power or starting the exhaust system;
9、Power supply requirements: The standard provides specific requirements for the power supply voltage and continuous working time of battery powered and non battery powered instruments;
10、Other performance requirements: including requirements for orientation, response time, full-scale indication error, high-speed airflow, long-term stability, insulation and voltage resistance, temperature, constant humidity and heat, resistance to electromagnetic interference, resistance to steam interference, vibration drop, and functionality.
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