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 in various locations. We provide services nationwide, addressing electrical safety and explosion-proof fire prevention issues for customers, and contributing to safe production.
Calibration Method
Appearance and structure
Inspect visually and by touch, as per requirements of 4.1
Logos and Branding
Inspect as per requirement 4.2.
Power-on Inspection
Inspect visually and by touch in accordance with the requirements of 4.3 to check the alarm function and the alarm action values as per 5.3.4.
Introduce a standard gas substance with a concentration exceeding the alarm set point, causing the instrument to trigger an alarm. Observe whether the instrument's sound and light alarm functions normally and record the instrument's reading when the alarm is triggered. Repeat the measurement three times, and the arithmetic mean of the three readings is the instrument's alarm trigger value.

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

Routine Inspection Items for Environmental Gas Detection and Alarm Equipment in Workplaces:
Alarm sound and light (if applicable)
2. Small 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-吸取式 Instrument Gas Sampling Distance and Flow Rate (for Pump-吸取式 Instruments)
7. Power Supply (for battery-powered instruments)
8. Response Time
9. Status Indicator (with Wireless Communication Function)

Key Technical Requirements for Regular Calibration of Flammable Gas Detectors (Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Power-On Self-Check Function: The instrument should have an automatic self-check feature upon startup, with manual self-check options for alarm components as well.
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 oxygen deficiency alarm setpoint is 19.5%VOL, and the enriched oxygen alarm setpoint is 23.5%VOL (refer to GB 8958—2006 "Operation Regulations for Oxygen Deficiency Hazardous Operations" and GB 30871—2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level alarm setting for flammable gas should not exceed 25% LEL, and the second-level alarm setting should not exceed 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 (Immediately Dangerous to Life and Health concentration).
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 be no more than 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: Equipment for explosive environments must have explosion-proof capabilities in compliance with relevant regulations and obtain an explosion-proof certification.
7. Sound and Light Alarm Device: The sound and light 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 shutting off power or initiating an exhaust system, etc.
9. Power Supply Requirements: Specific requirements are outlined for the power voltage and continuous operating time of both battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including requirements for bearing, 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 drop, and functionality.
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 detection instruments for regular inspections, metrological measurements, and calibrations. We are qualified to address fire and explosion prevention issues for our clients.