Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, certification, and metrological services for equipment such as gas alarms, combustible gas detectors, and toxic and harmful gas detectors in various locations. We provide services nationwide to address various electrical safety and explosion-proof fire prevention issues for customers, contributing to safe production.
Gas Detector Alarm Calibration Standard Requirements
Regulation 5.5 of the "Regulation for Inspection and Verification of Flammable Gas Detectors" (JJG693-2011) states: The inspection period for flammable gas detection and alarm instruments: Generally, the inspection period for the instrument should not exceed one 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 inspection promptly.
Section 3.5 of the "Regulations for the Use of Combustible Gas Detection and Alarm Systems" (SY6503-2000) stipulates: Combustible gas detection and alarm systems in use shall be calibrated periodically as required.
Occupational Health Service (GBZ/T223-2009) Article 7.2.1 stipulates: Calibration of detection and alarm devices shall be performed 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 that the flammable gas detectors and alarms installed and used shall have measurement instruments manufactured by an institution recognized for their **instrumental accuracy** and **explosion-proof performance**.

Primary Technical Requirements for Regular Calibration of Combustible Gas Detectors (Shenzhen ZhongNuo Testing Technology Co., Ltd.)
1. Power-On Self-Check Function: The instrument should have an automatic self-check function upon startup, with a manual self-check function for alarm components as well.
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 Setting: Specific alarm value settings are stipulated for different gases according to the standard.
For example, the hypoxia alarm setpoint is 19.5%VOL, and the hyperoxia alarm setpoint is 23.5%VOL (refer to GB 8958-2006 "Operation Procedures for Hypoxia Hazardous Work" and GB 30871-2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level combustible gas alarm setting is not greater than 25% LEL, and the second-level alarm setting is not greater than 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 specifies clear requirements for the instrument's indication error, drift, and repeatability. For example, the indication 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 Interface: The instrument should be easy to calibrate, and calibration programs and corresponding interfaces should be set up to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Instruments used in explosive environments should possess explosion-proof performance in compliance with relevant regulations and obtain an explosion-proof certification.
7. Audio-Visual Alarm Devices: The audio-visual alarm devices of the alarm should meet specific visibility and sound pressure level requirements to ensure effective alerting of staff during emergencies.
8. Output Control Function: Instruments equipped with output control functionality should be able to activate such features upon emitting an alarm signal, including but not limited to, cutting off power supply or initiating an exhaust ventilation system.
9. Power Requirements: Specific requirements are set forth for the power voltage, continuous operating time, and other factors for battery-powered and non-battery-powered instruments.
10. Additional Performance Requirements: Includes specifications for bearing, response time, full-scale indication error, high-speed airflow, long-term stability, insulation and voltage resistance, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop resistance, and functionality.

Calibration Method
Appearance and structure
Inspect visually and by touch in accordance with the requirements of Section 4.1
Logos and Branding
Inspect in accordance with the requirements of 4.2 by sight.
Power-on Inspection
Inspect visually and by touch according to the requirements of 4.3 to check the alarm function and alarm action values as per 5.3.4.
Introduce a standard gas substance with a concentration exceeding the alarm set point, causing the instrument to trigger an alarm. Observe if the instrument's audio-visual alarm functions normally and record the instrument's reading at the time of alarm. Repeat the measurement three times; the arithmetic mean of the three readings is the instrument's alarm trigger value.

Gas Standard Material
The standard gas used should be a substance of the same type as the gas being measured by the instrument, such as methane or other gases; alternative substances like isopropanol can also be used. If the instrument does not specify the type of gas being measured, the concentration of the gas, such as methane, at the set point should be approximately 60% of the full scale. The uncertainty of the expanded gas standard substance should not be more than a certain percentage (%). The flow indication error of the repetitive dilution device should not be higher than a certain value for gases with higher concentrations. The concentration unit of the gas standard substance should be converted to match the unit of the instrument being tested during use, and the deviation should not exceed 0.%.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is an independent third-party service provider specializing in electrical safety, electrical explosion-proofing, gas alarm systems, and toxic and harmful gas detection instruments, offering regular inspections, metrological services, and calibration. We are qualified to address fire and explosion prevention issues for our clients.