Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the calibration, certification, and measurement services for gas alarms, combustible gas detectors, toxic gas analyzers, and other equipment used in various locations. We serve nationwide, addressing customers' electrical safety and explosion-proof fire prevention needs, and supporting safe production.
Gas Standard Material
We use gas standard substances of the same type as the gas measured by the instrument, such as methane or ethane, or gas standards can be expanded with isopropanol, etc. If the instrument does not specify the type of gas being measured, the concentration of the gas at the set point for methane, ethane, or other gases is approximately 60% of the full scale. The uncertainty of the expanded gas standard substances is not more than % (k-body standard substances greater than ±1%). The flow indication error of the repetitive dilution device should not be greater than 0.%. The concentration unit of the gas standard substance should be converted to match the indicating unit of the tested instrument when in use.

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, and a manual self-check function should be 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 m.
3. Alarm Value Setting: The standard specifies specific alarm value settings for different gases.
For example, the hypoxia alarm set point is 19.5% VOL, and the hyperoxia alarm set point 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 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 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 shutting off power or initiating an exhaust system, etc.
9. Power Requirements: Specific requirements are set for the supply voltage, continuous operating time, etc., of battery-powered and non-battery-powered instruments.
10. Additional Performance Requirements: Includes specifications for bearing, response time, full-range indication error, high-speed airflow, long-term stability, insulation and voltage resistance, temperature, constant humidity and heat, resistance to electromagnetic interference, resistance to steam interference, vibration and shock, and functional requirements.

Regular inspection items for environmental gas detection and alarm instruments at work sites:
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 collection distance and flow rate (for pump-suction instruments)
7. Power Supply (for battery-powered instruments)
8. Response Time
9. Status Indicator (with Wireless Communication Function)

Power-on inspection
The instrument should operate normally and display parts should be clear and complete after being powered on. Check the alarm function and the alarm trigger values.
Alarm function and alarm action value verification
The instrument's sound and light alarm should function normally. Insulation resistance
Insulation resistance for equipment using AC power should not be less than 20MΩ.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is a third-party institution providing regular certification, measurement, and calibration services for electrical safety, electrical explosion-proof, gas alarms, and toxic gas detection instruments, as well as solving fire and explosion prevention issues for customers.