Shenzhen ZhongNuo Inspection & Technology Co., Ltd. specializes in the calibration, certification, and measurement services for equipment such as gas alarms, flammable gas detectors, and toxic/hazardous gas detection instruments for various locations. We provide nationwide services to address clients' electrical safety and explosion-proof fire prevention needs, contributing to safe production and operation.
How often is it required to perform regular calibration and inspection on various gas detectors?
The recalibration period for instruments is typically one 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 needed after repair.

Regulatory contents for regular gas alarm inspections
Installation spacing of inspection (detection) points
2. Installation Height of the Detector
3. Indication Error (Concentration)
4. Repeatability (Concentration)
5. Alarm Error (Concentration)
6. Response Time (seconds)

Calibration Method
Appearance and structure
Inspect and feel 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, checking the alarm function and alarm action values according to the requirements of 4.3.
Introduce a standard gas substance with a concentration exceeding the alarm set point, causing the instrument to trigger an alarm. Observe whether the instrument's sound and light alarm functions normally and record the instrument's reading when the alarm is triggered. Repeat the measurement three times, and the arithmetic mean of the three readings is the instrument's alarm trigger value.

Technical Requirements for Regular Calibration of Flammable Gas Detectors (Shenzhen Zhongnuo Inspection Technology Co., Ltd.)
1. Power-On Self-Check Function: The instrument should have an automatic self-check function upon startup, and the alarm components should also be equipped with a manual self-check option.
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 oxygen deficiency alarm setting is 19.5%VOL, and the enriched oxygen alarm setting is 23.5%VOL (refer to GB 8958—2006 "Operation Code for Oxygen Deficiency Hazardous Operations," 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 specifies clear requirements for the instrument's indication error, drift, and repeatability. For instance, 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 Interfaces: The instrument should be easy to calibrate, with a set calibration program 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 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 set for the supply voltage, continuous operating time, etc., of battery-powered and non-battery-powered instruments.
10. Other Performance Requirements: Including requirements for azimuth, response time, full-scale indication error, high-speed airflow, long-term stability, insulation withstand voltage performance, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop, and functionality.
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 alarm instruments for regular inspections, metrological measurements, and calibrations. We are licensed to address fire and explosion prevention issues for our clients.