Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the certification, calibration, and metrological services for equipment such as gas detectors, combustible gas detectors, and harmful gas detection instruments for various locations. With qualifications to serve nationwide, we provide solutions for all types of electrical safety and explosion-proof fire prevention issues, facilitating safe production.
Key Technical Requirements for Periodic Inspection of Combustible Gas Detectors (Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Self-check feature upon startup: The instrument should have an automatic self-check function upon startup, and a manual self-check function for alarm components should also be set.
2. Specify the effective detection distance: The effective detection distance of the non-contact gas alarm instrument shall not be less than 20 m.
3. Alarm Value Settings: For different gases, the standard specifies specific alarm value settings.
For example, the hypoxia alarm set value is 19.5% VOL, and the hyperoxia alarm set value is 23.5% VOL (refer to GB 8958-2006 "Operation Code for Hypoxia Hazardous Work" and GB 30871-2022 "Special Operation Code for Hazardous Chemical Enterprises").
The first-level combustible gas alarm set point does not exceed 25% LEL, and the second-level alarm set point does not exceed 50% LEL.
The first and second level alarm settings for toxic and harmful gases are determined based on the OEL (Occupational Exposure Limit) or IDLH (Immediate Danger to Life and Health).
4. Error and Repetition: The standard sets clear requirements for the indicating error, drift, and repeatability of the instrument. For example, the indicating error for combustible gases, toxic and harmful gases, and oxygen should not exceed 5% FS, 5% FS, and 2% FS respectively within the normal test range of the instrument's full scale.
5. Calibration and Interfaces: The instrument should be easy to calibrate, with set calibration procedures 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 compliance with relevant regulations and obtain an explosion-proof certification.
7. Audio-Visual Alarm Device: The audio-visual alarm device of the alarm should meet visibility and sound pressure level requirements under specific conditions, ensuring effective alerting of staff during emergencies.
8. Output Control Function: Instruments with output control functionality should be able to activate the output control feature upon emitting an alarm signal, such as shutting off power or initiating the exhaust system, etc.
9. Power Requirements: Specific requirements are set for the supply voltage, continuous operating time, etc., of battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including requirements for bearing, response time, full-scale indication error, high-speed airflow, long-term stability, insulation withstand voltage, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop, and functionality.

What factors can affect the calibration cycle of a flammable gas detector?
Manufacturer Requirements: Flammable gas detectors from different manufacturers may have varying inspection cycle requirements. Therefore, when purchasing equipment, carefully review the product manual to understand the specific requirements of the manufacturer.
Equipment Usage Environment: The operating environment of the alarm directly affects its inspection cycle. If the equipment is frequently exposed to high concentrations of harmful gases, high or low humidity, or high or low temperatures for extended periods, its inspection cycle may be shortened accordingly.
‌Equipment Maintenance Status: The condition of equipment maintenance is also a significant factor affecting the inspection cycle. If the equipment frequently faces issues such as battery depletion or aging sensors, its inspection cycle will correspondingly be shortened.

Gas Detector Alarm Calibration Standard Requirements
Section 5.5 of the "Regulation for Calibration of Combustible Gas Detectors" (JJG693-2011) stipulates: The calibration cycle for combustible gas detection and alarm instruments: Generally, the calibration cycle of the instrument shall not exceed 1 year. If there is any doubt about the measurement data of the instrument, or if the instrument has been replaced with major components or repaired, it should be sent for calibration promptly.
Section 3.5 of the "Code for the Use of Combustible Gas Detection and Alarm Devices" (SY6503-2000) stipulates: The combustible gas detection and alarm devices in use shall be calibrated regularly as per the regulations.
Section 7.2.1 of "Code for Setting of Toxic Gas Devices in Workplaces" (GBZ/T223-2009) stipulates: Calibration of detection and alarm devices should be carried out regularly according to the manufacturer's specified time and procedures.
Section 3.4 of the "Regulations for the Use of Flammable Gas Detectors and Alarms" (SY6503-2000) stipulates: Flammable gas detectors and alarms for installation and use shall have measuring instruments manufactured by recognized agencies with **excellent explosion-proof performance**.

Power-on inspection
The instrument should operate normally after being powered on, with the display section being clear and complete. Check the alarm function and alarm trigger values.
Alarm function and alarm action value verification
The instrument's sound and light alarm should be functioning normally. Insulation resistance
Insulation resistance for equipment using AC power should be no less than 20MΩ.
Shenzhen ZhongNuo Testing Technology Co., Ltd. is a third-party institution specializing in electrical safety, electrical explosion-proofing, gas alarm systems, and toxic and harmful gas alarm instruments. We offer regular inspections, metrological services, and calibration. Our资质 ensures we provide solutions for fire and explosion prevention issues to our clients.