Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, verification, and measurement services for gas alarms, combustible gas detectors, and toxic gas detection instruments for various locations. We hold the necessary qualifications to serve nationwide, addressing clients' electrical safety and explosion-proof fire prevention needs, and contributing to safe production.
Gas Standard Material
The gas standard substance used should be of the same type as the gas measured by the instrument, such as methane or ethane, or alternative alcohols can be used for gas standards. If the instrument does not specify the type of gas being measured, the concentration of the gas, such as methane, ethane, or警设定点涨度的气, at 60% is approximately equal to the full-scale standard. The uncertainty of the expanded gas standard substance is not significant (%), and the standard gas should be diluted with a repeatability of no more than 1%. The flow indication error of the dilution device should not be greater than 0.%. The concentration unit of the gas standard substance should be converted to match the unit of the inspected instrument, and should not exceed 0.%.

Primary technical requirements for regular calibration of flammable gas detection and alarm devices (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. Specify the effective detection range: The effective detection range of the non-contact gas alarm instrument shall not be less than 20 m.
3. Alarm Value Settings: Specific alarm value settings are stipulated for different gases in accordance with the standard.
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 Procedures for Hypoxia Hazardous Work" and GB 30871-2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level flammable 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 a set calibration program and corresponding interface to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Instruments used in explosive environments must have explosion-proof performance in accordance 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 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 Supply Requirements: Specific requirements are outlined for the supply voltage, continuous operating time, and other factors for battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Includes specifications for azimuth, 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, and functional aspects.

The detection principle of the instruments mainly includes catalytic combustion, infrared absorption, and thermal conductivity types. The sampling methods include 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.

Instrument Control
Instrument control includes calibration, follow-up calibration, and in-service inspection.
Shenzhen ZhongNuo Testing Technology Co., Ltd. is a third-party institution specializing in electrical safety, electrical explosion-proofing, gas alarms, and toxic gas detection equipment for regular inspections, metrological measurements, and calibration services. We are qualified to address fire and explosion prevention issues for our clients.