Shanghai Combustible Gas Detector Calibration Agency

Shenzhen ZhongNuo Inspection & Technology Co., Ltd. specializes in the calibration, certification, and metrological services for gas alarms, combustible gas detectors, toxic and harmful gas detectors, and other equipment in various locations. We provide nationwide services to address various electrical safety and explosion-proof fire prevention issues for customers, contributing to safe production.
Calibration Method
Appearance and structure
Inspect visually and by touch in accordance with requirements of 4.1
Logos and Identifiers
Observe as per 4.2 requirements.
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 setting point, causing the instrument to trigger an alarm. Observe whether the instrument's sound and light alarms are functioning properly, and record the readings at the time of the alarm. Repeat the measurement three times, with the arithmetic mean of the three readings being the instrument's alarm trigger value.

How often should various gas detectors be periodically inspected and calibrated?
Instrument recalibration is typically every 1 year, determined by the submitting unit based on actual usage. During the secondary calibration process, recalibration is required if there are doubts about the instrument's test data, if the main components of the instrument are replaced, or if recalibration is necessary after repairs.

Key Technical Requirements for Regular Calibration of Combustible Gas Detectors (Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Self-check function upon startup: The instrument should have an automatic self-check function upon startup, and a manual self-check function should also 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 meters.
3. Alarm Value Setting: Specific alarm value settings are stipulated for different gases in accordance with the standard.
For example, the oxygen deficiency alarm setpoint is 19.5% VOL, and the high-oxygen alarm setpoint 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 alarm setting for flammable gases should not exceed 25% LEL, and the second-level alarm setting should 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 (Immediate Danger to Life and Health).
4. Error and Reproducibility: The standard specifies clear requirements for the instrument's indication error, drift, and reproducibility. 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, with established calibration programs and corresponding interfaces to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Equipment for explosive environments should possess 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 the visibility and sound pressure level requirements under specific conditions, ensuring effective alerting of staff in emergency situations.
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 the exhaust system, etc.
9. Power Requirements: Specific requirements are outlined for power supply voltage, continuous operating time, etc., for both battery-powered and non-battery-powered instruments.
10. Additional Performance Requirements: Includes specifications for azimuth, response time, full-range indication error, high-speed airflow, long-term stability, insulation withstand voltage, temperature, constant humidity and heat, resistance to electromagnetic interference, resistance to steam interference, vibration and shock, and functional requirements.

Standard for certification and metrological calibration of flammable and toxic gases detectors:
Standard GB/T50493-2019 "Design Standard for Detection and Alarm Systems of Combustible Gases and Toxic Gases in Petroleum and Chemical Industry"
GB12358-2006 General Technical Requirements for Environmental Gas Detection and Alarm Instruments in Workplace
JJG693-2011 "Regulation for Calibration of Combustible Gas Detectors"
Shenzhen Zhongnuo Testing Technology Co., Ltd. is a third-party institution specializing in electrical safety, electrical explosion-proofing, gas alarms, and toxic and harmful gas alarm instruments for regular inspections, metrological measurements, and calibrations. We provide资质 services to address fire and explosion prevention issues for our clients.