Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, certification, and measurement services for gas alarms, combustible gas detectors, and toxic gas detection instruments for various locations. We provide services nationwide, addressing electrical safety and explosion-proof fire prevention issues for clients, and contributing to safe production.
Gas Alarm Meters Calibration Conditions and Requirements
Environmental Conditions
Ambient Temperature: 0~40℃.
2. Relative Humidity: ≤85%
3. The working environment should not affect the normal operation of the instrument with electromagnetic fields and interfering gases.
Calibration Tools and Instruments
1) Standard Gas Substance
The relative expanded uncertainty of the gas standard material does not exceed 2% (k=2).
2) Standard Gas Dilution Unit: Dilution Error of 1%.
3) Stopwatch: Graduation not greater than 0.1s.
4) Flow Control: Flow range not less than 500 mL/min, flow grade not less than level 4.
5) Zero Point Gas: Purified compressed air.
6) Pressure Relief Valve: A pressure relief valve that matches with the calibrated cylinder.
7) Gas Pipeline: Tube for gas piping that does not affect the concentration of the tested gas, such as polytetrafluoroethylene or stainless steel piping.

Appearance and structure
The instrument should not have any surface damage that affects its normal operation. The surface of newly manufactured instruments should be smooth and glossy, with a uniform paint and plating layer, free of peeling and rusting.
The instrument connection is reliable, and all dials or buttons should operate and control normally.
Branding and Identification
Instrument name, model, manufacturer's name, date of manufacture, serial number, explosion-proof marking and number, as well as the manufacturing metrological instrument license marking and number for domestic instruments should be clear.

Instrument Calibration Control
Instrument control includes calibration, subsequent calibration, and in-use inspection.

Key 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 also 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: The standard specifies specific alarm value settings for different gases.
For example, the hypoxia alarm setting is 19.5% VOL, and the hyperoxia alarm setting 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 setpoint is not greater than 25% LEL, and the second-level alarm setpoint 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 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, with set calibration programs and corresponding interfaces to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Equipment used in explosive environments must have explosion-proof performance in accordance with relevant regulations and obtain an explosion-proof qualification certificate.
7. Audio-Visual Alarm Devices: The alarm's audio-visual alarm system must meet visibility and sound pressure level requirements under specific conditions to ensure effective notification to staff during emergencies.
8. Output Control Function: Instruments equipped with output control functionality should be capable of initiating the output control feature upon emitting an alarm signal, such as shutting off power or activating 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. Additional Performance Requirements: Includes specifications for bearing, response time, full-scale 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 drop, and functionality.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is an independent third-party service provider specializing in electrical safety, electrical explosion-proof, gas detectors, and toxic and harmful gas alarm instruments for regular calibration, measurement, and certification. We offer qualifications to help clients address fire and explosion prevention issues.