Shenzhen ZhongNuo Inspection Technology Co., Ltd. specializes in the calibration, verification, and measurement services for equipment such as gas alarms, combustible gas detectors, and toxic gas detection instruments for various locations. We hold the necessary qualifications to serve customers nationwide, addressing all types of electrical safety and explosion-proof fire prevention issues, and contributing to safe production.
How often should various gas detectors be periodically inspected and calibrated?
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.

Regulatory Content for Periodic Inspection of Gas Alarms
Installation spacing of inspection (testing) points
2. Installation Height of the Detector
3. Indication Error (Concentration)
4. Repetition (Concentration)
5. Alarm Error (Concentration)
6. Response Time (seconds)

Verification Method
Appearance and structure
Inspect and feel in accordance with requirements of Section 4.1
Branding and Logos
Inspect in accordance with the requirements of Section 4.2.
Power-on inspection
Inspect visually and by touch, checking the alarm function and alarm action values in accordance with 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 alarms are functioning properly and record the instrument's readings when the alarm is activated. Repeat the measurement three times, and the arithmetic mean of the three readings is the instrument's alarm activation value.

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 manual self-check capabilities for alarm components as well.
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 in accordance with the standard.
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 Oxygen Deficiency Hazardous Operations," GB 30871—2022 "Special Operation Regulations for Hazardous Chemical Enterprises").
The first-level flammable 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 instrument's 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 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 accordance 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 functionality should be capable of activating 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 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 resistance, 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 verification, measurement, and calibration services. We are qualified to address fire and explosion prevention issues for our clients.