Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the calibration, certification, and measurement services for gas alarms, combustible gas detectors, toxic and harmful gas detectors, and other equipment at various locations. We offer nationwide services to address electrical safety and explosion-proof fire prevention issues for clients, supporting safe production.
Primary technical requirements for regular calibration of combustible gas detectors (Shenzhen ZhongNuo Inspection & Testing Technology Co., Ltd.)
1. Power-On Self-Check Function: The instrument should have an automatic self-check function upon startup, and the alarm components should also be equipped with a manual self-check option.
2. Specified Effective Detection Distance: The effective detection distance of the non-contact gas alarm instrument is not 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 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 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 Repeatability: 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 alerting of 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 the exhaust system, etc.
9. Power Supply Requirements: Specific requirements are outlined for the supply voltage, continuous operating time, etc., of battery-powered and non-battery-powered instruments.
10. Additional Performance Requirements: Including specifications for direction, 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 resistance, and functionality.

Which gas detectors require regular calibration and verification?
All types of in-use fixed installation, handheld, portable gas detectors, gas alarm instruments, toxic and harmful gas detectors/alarm, flammable gas detectors/alarm, gas analyzers, etc.

The detection principle of the instruments mainly includes catalytic combustion, infrared absorption, and thermal conductivity types. The sampling methods are diffusion and aspiration. The instruments are primarily composed of detection elements, amplification circuits, alarm systems, and displays, used for monitoring the concentration of combustible gases in the environment.

Gas Alarm Meters Calibration Conditions and Requirements
Environmental Conditions
Ambient Temperature: 0~40℃.
2. Relative Humidity: ≤85%
3. The working environment should not interfere with the electromagnetic field and interfere gases that affect the normal operation of the instrument.
Calibration Tools and Instruments
1) Certified Gas Standards
The relative expanded uncertainty of the gas standard material does not exceed 2% (k=2).
2) Standard Gas Dilution Device: Dilution error of 1%.
3) Stopwatch: graduation not greater than 0.1s.
4) Flow Control: Flow rate not less than 500 mL/min, flow grade not less than level 4.
5) Zero Point Gas: Purified compressed air.
6) Pressure Reducing Valve: A pressure reducing valve that is compatible with the calibrated cylinder.
7) Gas Pipeline: Use气管 made of materials such as polytetrafluoroethylene or stainless steel that do not affect the concentration of the measured gas.
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 calibration services. We provide资质 to address fire and explosion prevention issues for our clients.