Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the certification, calibration, and metrological services for gas alarms, flammable gas detectors, and toxic/hazardous gas detection instruments at various sites. We are fully licensed to serve nationwide, providing solutions to electrical safety and explosion-proof/fire prevention issues for clients, and contributing to safe production.
Rechargeable Gas Detector Alarm Regular Inspection Content and Methods
Annually, we conduct annual inspections on the sensors of commercial and industrial alarm systems, primarily checking for measurement errors, repeatability, drift, and response times to ensure they meet standards. Additionally, we verify the suitability of the alarm system's installation location and check for any interference from other equipment.

Regular Inspection Content for Gas Alarm Units
Installation spacing of inspection (testing) points
2. Installation Height of the Detector
3. Indicated Error (Concentration)
Repeatability (Concentration)
5. Alarm Error (Concentration)
6. Response Time (seconds)

Gas Standard Material
We use gas standard substances of the same type as the gas measured by the instrument, such as methane or ethane, or alternative substances like isopropanol can be used. If the instrument does not specify the type of gas being measured, the concentration of the gas at the set point for methane, ethane, or other gases should be approximately 60% of the full scale. The uncertainty in the expansion of the standard gas is not significant (%), and the standard gas substance should have a repeatability of more than 1%. The flow indication error of the dilution device should not be greater than 0.%. The concentration unit of the dilution gas standard substance should be converted to match the units of the instrument being tested, and the discrepancy should not exceed 0.%.

Primary Technical Requirements for Regular Calibration of Flammable Gas Detectors (Shenzhen ZhongNuo Inspection & Testing 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 should be set for alarm components.
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: The standard specifies specific alarm value settings for different gases.
For example, the oxygen deficiency alarm setting is 19.5% VOL, and the oxygen-rich alarm setting is 23.5% VOL (refer to GB 8958-2006 "Operation Procedures for Oxygen Deficiency Hazardous Operations" and GB 30871-2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level combustible gas alarm setpoint is not greater than 25% LEL, and the second-level alarm setpoint is not greater than 50% LEL.
The first and second alarm setpoints 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 instance, 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 be 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 possess explosion-proof performance in compliance with relevant regulations and obtain an explosion-proof certification.
7. Audio-Visual Alarm Device: The alarm's audio-visual alarm device must meet visibility and sound pressure level requirements under specific conditions to ensure effective notification to staff during emergencies.
8. Output Control Function: Instruments with output control capabilities should be able to activate the output control function upon emitting an alarm signal, such as cutting off power supply or initiating an exhaust system, etc.
9. Power Requirements: Specific requirements are outlined for the supply voltage, continuous operating time, etc., for battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Includes specifications for bearing, response time, full-scale indication error, high-speed airflow, long-term stability, insulation voltage resistance, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop resistance, and functionality.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is a third-party institution that specializes in electrical safety, electrical explosion-proofing, gas alarm systems, and toxic/hazardous gas alarm instruments for regular calibration, measurement, and certification services, with qualifications to assist customers in solving fire and explosion prevention issues.