Shenzhen ZhongNuo Testing Technology Co., Ltd. specializes in the calibration, certification, and metrological 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 clients, and contributing to safe production.
Appearance and structure
The instrument should not have any surface damage that affects its normal operation. The surface of newly manufactured instruments should be smooth and glossy, with a uniform paint and plating coating, free of peeling and rusting.
The instrument's connections are reliable, and all dials or buttons should operate and control normally.
Branding and logos
Instrument name, model, manufacturer's name, manufacturing date, serial number, explosion-proof markings and numbers, as well as the manufacturing metrological instrument license mark and number for domestic instruments, should be clear.

Key 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, with an additional manual self-check function 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 setting is 19.5% VOL, and the hyperoxia alarm setting is 23.5% VOL (refer to GB 8958-2006 "Operation Code for Oxygen Deficiency Hazardous Work" and GB 30871-2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level flammable 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 specifies clear requirements for the instrument's indication error, drift, and repeatability. For example, the indication error for flammable 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 used in explosive environments should have explosion-proof performance in accordance 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 visibility and sound pressure level requirements under specific conditions to ensure effective alerting of staff in 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 the exhaust system, etc.
9. Power Requirements: Specific requirements are outlined for power supply voltage, continuous operating time, etc., for both battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including specifications for direction, response time, full-range indication error, high-speed airflow, long-term stability, insulation withstand voltage performance, temperature, constant humidity and heat, resistance to electromagnetic interference, resistance to steam interference, vibration and shock resistance, and functional aspects.

The calibration cycle for flammable gas detectors is typically once a year.
In accordance with the standard JJG 693-2011 "Flammable Gas Detectors," the calibration period for flammable gas detectors generally does not exceed one year. This means that under normal circumstances, a comprehensive calibration and testing of the flammable gas detectors should be conducted annually to ensure their performance meets the relevant requirements.

Which gas detectors require regular calibration and verification?
Fixed-installed, handheld, portable gas alarms, gas detectors, toxic and harmful gas detectors/alarm systems, flammable gas detectors/alarm systems, gas analyzers, etc.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is an independent third-party service provider specializing in electrical safety, electrical explosion-proofing, gas alarms, and toxic and harmful gas alarm instruments for regular inspections, metrological measurements, and calibrations. We hold the necessary qualifications to assist clients in addressing fire and explosion prevention issues.