Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the calibration, verification, and metrological services for gas alarms, combustible gas detectors, and toxic gas detection instruments for various locations. We hold qualifications to serve nationwide, addressing electrical safety and explosion-proof fire prevention issues for clients, and contributing to safe production.
Appearance and structure
The instrument should not have any appearance damage that affects its normal operation. The surface of newly manufactured instruments should be smooth and even, with a uniform paint and coating, free from peeling and rusting.
The instrument's connections are reliable, and all dials or buttons should operate and control normally.
Logos and Branding
Instrument name, model, manufacturer's name, date of manufacture, serial number, explosion-proof marking and number, as well as the manufacturing measurement instrument license marking and number for domestic instruments should be clear.

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 an additional manual self-check function 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 Settings: The standard specifies specific alarm value settings for different gases.
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 Regulations for Oxygen Deficient 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, 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 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 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 power supply voltage, continuous operating time, etc., for battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including requirements for azimuth, response time, full-scale indication error, high-speed airflow, long-term stability, insulation withstand voltage performance, temperature, constant humidity and heat, resistance to electromagnetic interference, resistance to steam interference, vibration and drop, and functionality.

The principle of instrument detection mainly includes catalytic combustion, infrared absorption, and thermal conductive types. Sampling methods include diffusion and aspiration. The instrument is primarily composed of detection elements, amplification circuits, alarm systems, and displays, used for monitoring the concentration of combustible gases in the environment.

Gas Detector Alarm Calibration Specification Requirements
Regulation 5.5 of the "Regulation for Inspection and Verification of Combustible Gas Detectors" (JJG693-2011) stipulates: The inspection cycle for combustible gas detection and alarm instruments: Generally, the inspection cycle of the instrument should not exceed one year. If there is any doubt about the instrument's measurement data, or if the instrument has been replaced with major components or repaired, it should be promptly submitted for inspection.
Section 3.5 of the "Code for the Use of Combustible Gas Detection and Alarm Systems" (SY6503-2000) stipulates: The combustible gas detection and alarm systems in use shall be calibrated periodically as per the regulations.
Occupational Health Service Station Toxic Gas Device Installation Specification (GBZ/T223-2009) Article 7.2.1 stipulates: Calibration of detection and alarm devices shall be carried out regularly according to the manufacturer's specified time and procedures.
Section 3.4 of the "Regulations for the Use of Combustible Gas Detectors" (SY6503-2000) stipulates: Combustible gas detectors for installation and use should have measurement instruments manufactured by an institutionally recognized manufacturer, with explosion-proof performance.
Shenzhen ZhongNuo Inspection & Testing Technology Co., Ltd. is a third-party organization specializing in electrical safety, electrical explosion-proofing, gas alarm systems, and toxic and harmful gas detection instruments. We offer regular calibration, measurement, and certification services, as well as qualifications to address fire and explosion prevention issues for our clients.