Shenzhen Zhongnuo Testing Technology Co., Ltd. specializes in the calibration, verification, and measurement services for gas alarms, combustible gas detectors, toxic and harmful gas detectors, and other equipment at various locations. With qualifications to serve nationwide, we address various electrical safety and explosion-proof fire prevention issues for clients, contributing to safe production.
Primary Technical Requirements for Regular Calibration of Combustible Gas Detectors (Shenzhen Zhongnuo Inspection Technology Co., Ltd.)
1. Self-check feature upon startup: The instrument should have an automatic self-check function when turned on, with the alarm components requiring a manual self-check function as well.
2. Specify Effective Detection Range: The effective detection range 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 oxygen-rich alarm setting is 23.5%VOL (refer to GB 8958-2006 "Operation Code for Oxygen Deficiency Hazardous Work" and GB 30871-2022 "Special Operation Code for Hazardous Chemical Enterprises").
The first-level flammable gas alarm setpoint does not exceed 25% LEL, and the second-level alarm setpoint does not exceed 50% LEL.
The first and second-level alarm settings for toxic and harmful gases are determined based on OEL (Occupational Exposure Limit) or IDLH (Immediate Danger to Life and Health).
4. Error and Repeatability: 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 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 have explosion-proof performance 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 functionality 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 power voltage, continuous working time, etc., for both 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, temperature, constant humidity and heat, electromagnetic interference resistance, steam interference resistance, vibration and drop, and functionality.

How often should various gas detectors be calibrated and inspected?
Instrument recalibration is typically every 1 year, determined by the submitting unit based on actual usage. During the secondary calibration process, recalibration is required if there are doubts about the instrument's test data, if the main components of the instrument are replaced, or if recalibration is needed after repairs.

Appearance and structure
The instrument should not have any appearance damage that affects its normal operation. The surface of newly manufactured instruments should be smooth and clean, with even paint and plating layers, free of peeling and rusting.
The instruments offer reliable connections, with all dials or buttons operable and controllable normally.
Branding and logos
Instrument name, model, manufacturer's name, manufacturing date, serial number, explosion-proof marking and number, as well as the manufacturing metrological instrument license marking and number for domestic instruments should be clear.

Regulatory Inspection Content for Gas Alarms
Installation spacing of inspection (probe) points
2. Installation Height of Detector
3. Indicated Error (Concentration)
4. Repetition (Concentration)
5. Alarm Error (Concentration)
6. Response Time (seconds)
Shenzhen ZhongNuo Testing Technology Co., Ltd. is a third-party institution providing regular calibration, measurement, and certification services for electrical safety, electrical explosion-proofing, gas alarms, and toxic gas detectors, as well as addressing fire and explosion prevention issues for customers.