Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, certification, and metrological services for gas detectors, flammable gas detectors, and harmful gas detection instruments in various locations. We provide services nationwide to address electrical safety and explosion-proof fire prevention issues for clients, 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 clean, with a uniform paint and plating coating, free from peeling and rusting.
The instruments feature reliable connections, with all dials or buttons operable and controllable normally.
Logos and branding
Instrument name, model, manufacturer's name, production date, serial number, explosion-proof mark and number, as well as the domestic instrument's manufacturing measurement instrument license mark and number should be clear.

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 also use 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 substance is not more than % (k-body standard substance greater than ±1%). The flow indication error of the repetitive dilution device should not be higher than the concentration of the gas standard substance. The concentration unit of the dilution device for gas standard substances should be converted to match the unit of the inspected instrument, and the deviation should not be greater than 0.%.

Primary technical requirements for periodic verification of flammable gas detection and alarm devices (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 also 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 meters.
3. Alarm Value Setting: 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 Procedures for Hypoxia Hazardous Work" and GB 30871-2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level combustible gas alarm setting is not greater than 25% LEL, and the second-level alarm setting 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 Reproducibility: The standard specifies clear requirements for the instrument's indication error, drift, and reproducibility. For example, 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 procedures and corresponding interfaces to ensure the accuracy of its measurement results.
6. Explosion-proof Performance: Equipment intended for explosive environments must possess explosion-proof characteristics in compliance 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 notification 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 or initiating a ventilation system, etc.
9. Power Requirements: Specific requirements are outlined for power supply voltage, continuous operating time, etc., for battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including 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 functionality.

Regular inspection items for environmental gas detection and alarm instruments in work场所:
1. Alarm sound and light (if applicable)
2. Small response value
3. Indicating Error (for Gas Detectors/Gas Detector Alarms)
4. Instrument Drift (in Portable Instruments)
5. Alarm Error (for Gas Detection Alarm / Gas Alarm)
6. Pump-Actuated Instrument Gas Sampling Distance and Flow Rate (for Pump-Actuated Instruments)
7. Power Supply (for battery-powered instruments)
8. Response Time
9. Status Indicator (with Wireless Communication Function)
Shenzhen ZhongNuo Testing Technology Co., Ltd. is an independent third-party institution offering regular calibration, measurement, and certification services for electrical safety, electrical explosion-proofing, gas alarms, and toxic gas detection instruments. We hold the necessary qualifications to assist clients in addressing fire and explosion prevention issues.