Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the certification, calibration, and metrological services for gas alarms, flammable gas detectors, toxic and harmful gas detectors, and other equipment in various locations. We hold qualifications to serve nationwide, addressing all types of electrical safety and explosion-proof fire prevention issues for our clients, and contributing to safe production.
Primary Technical Requirements for Regular Calibration of Flammable Gas Detectors (Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Self-check feature upon startup: The instrument should have an automatic self-check function upon startup, and a manual self-check function for alarm components should also be set.
2. Specify the effective detection distance: The effective detection distance of non-contact gas alarm instruments 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 setting is 19.5% VOL, and the hyperoxia alarm setting 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 Repetition: The standard sets clear requirements for the instrument's indication error, drift, and repeatability. 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: Instruments used in explosive environments should possess explosion-proof properties 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 alerting of staff during emergencies.
8. Output Control Function: Instruments equipped with output control 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 Supply Requirements: Specific requirements are outlined for the 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-range indication error, high-speed airflow, long-term stability, insulation withstand voltage, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and shock, and functionality.

Instrument Calibration Control
Instrument control includes calibration, follow-up calibration, and in-service inspection.

Gas Detector Alarm Calibration Specification Requirements
Section 5.5 of the "Regulation for the Verification of Combustible Gas Detectors" (JJG693-2011) stipulates: The verification cycle for combustible gas detection and alarm instruments: Generally, the verification cycle of the instrument should not exceed one year. If there is any doubt about the instrument's measurement data, or if the instrument has been replaced with major components or repaired, it should be promptly submitted for verification.
Section 3.5 of the "Regulations for the Use of Flammable Gas Detection and Alarm Systems" (SY6503-2000) stipulates: Flammable gas detection and alarm systems in use shall be calibrated regularly as required.
Section 7.2.1 of the "Code for the Installation of Toxic Gas Devices in Workplaces" (GBZ/T223-2009) stipulates: Calibration of detection and alarm devices should be performed regularly according to the manufacturer's specified time and procedures.
Section 3.4 of the "Regulations for the Use of Flammable Gas Detectors and Alarms" (SY6503-2000) stipulates that flammable gas detectors and alarms installed and used should have measuring instruments manufactured by recognized institutions with **measuring equipment** and **explosion-proof performance**.

How often should various gas detectors be periodically calibrated and tested?
Instrument recalibration is typically every 1 year, determined by the submitting unit based on actual usage. During the secondary calibration process, if there are doubts about the instrument's test data, or if the main components of the instrument are replaced, as well as after repairs, a re-calibration is required.
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 calibration, measurement, and certification services, with qualifications to address fire and explosion prevention issues for clients.