Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, certification, and metrological services for gas alarms, combustible gas detectors, and toxic gas detection instruments at various locations. We provide services nationwide, addressing electrical safety and explosion-proof fire prevention issues for customers, and contributing to safe production.
The principle of instrument detection mainly includes catalytic combustion, infrared absorption, and thermal conductivity 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.

Regular Inspection Items for Environmental Gas Detection and Alarm Equipment in Workplaces:
Alarm sound and light (if applicable)
2. Low response value
3. Indication Error (for Gas Detectors/Gas Detector Alarms)
4. Instrument Drift (in Portable Instruments)
5. Alarm Error (for Gas Detection Alarm / Gas Alarm)
6. Pump-suction Instrument Gas Sampling Distance and Flow Rate (for Pump-suction Instruments)
7. Power Supply (for battery-operated equipment)
8. Response Time
9. Status Indicator (with Wireless Communication Function)

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 feature upon startup, with the alarm components also requiring a manual self-check option.
2. Specify the effective detection distance: The effective detection distance 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 setting is 19.5% VOL, and the hyperoxia alarm setting is 23.5% VOL (refer to GB 8958-2006 "Operation Procedures for Hypoxia Hazardous Operations" and GB 30871-2022 "Special Operations 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 established calibration programs and corresponding interfaces to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Equipment for explosive environments must have explosion-proof performance in compliance with relevant regulations and obtain an explosion-proof certification.
7. Audio-Visual Alarm Devices: The audio-visual alarm device of the alarm should meet 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 supply voltage, continuous operating time, etc., of battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including requirements for bearing direction, response time, full-scale indication error, high-speed airflow, long-term stability, insulation withstand voltage performance, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop, and functionality.

Measurement Equipment 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 alarm systems, and toxic/hazardous gas detection instruments for regular inspections, metrological measurements, and calibrations. We are licensed to provide solutions for fire and explosion prevention issues for our clients.