Shenzhen ZhongNuo Inspection & Technology Co., Ltd. specializes in the calibration, certification, and measurement services for gas alarms, flammable gas detectors, toxic and harmful gas detectors, and other equipment in various locations. We are licensed to serve nationwide, addressing electrical safety and explosion-proof fire prevention issues for clients, and contributing to safe production.
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 cycle 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.

Method of Verification
Appearance and structure
Inspect visually and by touch according to the requirements of 4.1
Logos and Branding
Inspection to be conducted in accordance with requirement 4.2.
Power-on inspection
Inspect visually and by touch, in accordance with 4.3 requirements, to check the 5.3.4 alarm function and alarm action values.
Introduce a standard gas substance with a concentration exceeding the alarm setpoint, causing the instrument to trigger an alarm. Observe whether the instrument's audio-visual alarm is functioning properly and record the instrument's reading when the alarm is triggered. Repeat the measurement three times; the arithmetic mean of the three readings is the instrument's alarm trigger value.

Primary Technical Requirements for Regular Calibration of Combustible Gas Detectors (Shenzhen ZhongNuo Inspection & Testing Technology Co., Ltd.)
1. Power-on self-check function: The instrument should have an automatic self-check feature upon startup, and a 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: Specific alarm value settings are stipulated for different gases according to the standard.
For example, the oxygen deficiency alarm setpoint is 19.5% VOL, and the oxygen enrichment alarm setpoint is 23.5% VOL (refer to GB 8958-2006 "Operation Code for Oxygen Deficiency Hazardous Operations" 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 instruments' 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 properties in compliance with relevant regulations and obtain an explosion-proof certificate.
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 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 the exhaust system, etc.
9. Power Supply Requirements: Specific requirements are outlined for the voltage and continuous operating time of 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, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop, and functionality.

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, or if recalibration is required after repairs.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is a third-party service provider specializing in electrical safety, electrical explosion prevention, gas detectors, and toxic/hazardous gas alarm instruments for regular verification, calibration, and metrological services. We are qualified to help customers address fire and explosion prevention issues.