Shenzhen ZhongNuo Inspection & Technology Co., Ltd. specializes in the calibration, verification, and measurement services for equipment such as gas alarms, combustible gas detectors, and harmful gas detectors for various locations. We offer qualifications and services nationwide, addressing electrical safety and explosion-proof fire prevention issues for our clients, and supporting safe production.
Power-on inspection
After power is applied to the instrument, it should operate normally with clear and complete display. Check the alarm function and alarm trigger values.
Alarm function and alarm action value check
The instrument's acoustic and light alarm should be functioning normally. Insulation resistance.
Insulation resistance for instruments using AC power should be not less than 20MΩ.

Regular Testing Contents and Methods for Combustible Gas Detectors
Annual inspections are conducted on industrial and commercial alarm sensors, primarily checking for accuracy errors, repeatability, drift, and response time to ensure compliance with standards. Additionally, the installation location of the alarm sensors is assessed for suitability and any interference from other equipment.

What does a calibration report for a flammable gas detector typically include?
The verification results should be reflected in the verification certificate or report, and the verification proof or report must include the following information.
① Calibration Certificate or Calibration Report
② Laboratory Name and Address
③ Calibration Location (if not calibrated in the laboratory)
④ Standby letter of credit or report (e.g., numbered), with page markings and total page numbers indicated.
5. Shipper's name and address
⑥ Describe and clearly define the target school.
Calibration Date and Receipt Date
⑧ Technical specifications for calibration foundation, including names and codes;
Description of the traceability and validity of the measurement standards used for calibration.
⑩ Description of Calibration Environment
11. Calibration Results and Measurement Uncertainty Statement
12. Signature, title, or equivalent mark of the issuer of the calibration certificate or calibration report, and the issuance date.
13. Calibration results are only applicable to the calibration object.
14. No part of the certificate or report may be copied without written consent from the laboratory.
Re-review interval
Instrument recalibration is typically done 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, as well as after repairs, a recalibration is required.

Primary Technical Requirements for Regular Calibration of Combustible Gas Detectors (Shenzhen ZhongNuo Inspection Technology Co., Ltd.)
1. Self-check function upon startup: The instrument should have an automatic self-check feature upon startup, and the alarm components should also be equipped with a manual self-check function.
2. Specify 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 oxygen deficiency alarm setpoint is 19.5% VOL, and the oxygen-rich alarm setpoint is 23.5% VOL (refer to GB 8958—2006 "Operation Code for Oxygen Deficiency Hazardous Operations," GB 30871—2022 "Special Operation Specifications for Hazardous Chemical Enterprises").
The first-level flammable gas alarm setpoint is no greater than 25% LEL, and the second-level alarm setpoint is no greater than 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 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 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 for explosive environments must have explosion-proof performance in compliance with relevant regulations and obtain an explosion-proof certification.
7. Audio-Visual Alarm Device: The audio-visual alarm device of the alarm should meet specific visibility and sound pressure level requirements to ensure effective alerting of staff in emergency situations.
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 the 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, and function.
Shenzhen Zhongnuo Testing Technology Co., Ltd. is a third-party institution that offers regular calibration, metrological services, and calibration for electrical safety, electrical explosion-proof equipment, gas detectors, and toxic/hazardous gas alarm instruments, providing资质 to clients for fire and explosion prevention solutions.