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 in various locations. We hold qualifications to serve nationwide, addressing clients' electrical safety and explosion-proof fire prevention issues, and contributing to safe production.
Gas Standard Material
We use gas standard substances of the same type as the gas measured by the instrument, such as methane or ethane, or gas standards can also use isopropanol, etc. If the instrument does not specify the type of gas being measured, the concentration of the gas with a 60% range set point is approximately the full-scale standard substance. The uncertainty of the expanded gas standard substance is not significant (%). The flow indication error of the repetitive dilution device for gas standard substances with a concentration greater than 1% should not be higher than 0.%. The concentration unit of the dilution device for gas standard substances should be converted to match the unit of the inspected instrument, and the deviation should not exceed 0.%.

What does a calibration report for a flammable gas detector 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 numbers indicated on each page
5. Provide the sender's name and address.
⑥ Clearly describe and specify the target school.
Calibration date and receipt date;
⑧ Technical specifications for calibration foundation, including name and code;
Description of traceability and validity of the measurement standards used for calibration.
⑩ Description of Calibration Environment
11. Calibration Results and Measurement Uncertainty Statements
12. Signature, title, or equivalent symbol of the issuer of the calibration certificate or calibration report, and the issuance date;
13. Calibration results are only applicable to the verification object.
14. No part of the certificate or report may be copied without written approval from the laboratory.
Re-review interval
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, as well as after repairs, a recalibration is required.

Gas Alarm Meters Calibration Conditions and Requirements
Environmental Conditions
Ambient Temperature: 0~40℃.
Relative Humidity: ≤85%
3. The working environment should not affect the normal operation of the instrument with electromagnetic fields and interfering gases.
Inspection Tools and Instruments
1) Certified Gas Standards
The relative expanded uncertainty of the gas standard material does not exceed 2% (k=2).
2) Standard Gas Dilution Device: Dilution Error of 1%.
3) Stopwatch: Graduation not greater than 0.1s.
4) Flow Control: Flow range not less than 500 mL/min, flow grade not less than level 4.
5) Zero Point Gas: Purified compressed air.
6) Pressure Relief Valve: A pressure relief valve that is compatible with the calibrated cylinder.
7) Gas Pipeline:气管, made of materials such as polytetrafluoroethylene or stainless steel, that do not affect the concentration of the measured gas.

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, and a manual self-check function should be set for alarm components.
2. Specified 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 Regulations for Oxygen Deficiency Hazardous Operations," GB 30871-2022 "Special Operation Regulations for Chemical Hazardous Substance Enterprises").
The first-level alarm setting for flammable gases should not exceed 25% LEL, and the second-level alarm setting should not exceed 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 example, 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: Equipment for explosive environments must have explosion-proof performance 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 notification 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 Requirements: Specific requirements are outlined for the supply voltage, continuous operating time, etc., for battery-powered and non-battery-powered instruments.
10. Additional Performance Requirements: Including requirements for azimuth, response time, full-scale indication error, high-speed airflow, long-term stability, insulation voltage resistance, 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 that provides regular certification, measurement, and calibration services for electrical safety, electrical explosion-proofing, gas detectors, and toxic and harmful gas alarm instruments, as well as资质 to help customers solve fire and explosion prevention issues.