When calibrating a gas analyzer, it is necessary to follow national/industry standards, metrological technical specifications, and the operating guidelines of the instrument manufacturer. The core standards revolve around three dimensions: calibration methods, gas reference materials, and metrological performance requirements, as follows:
1、 Basic Metrology and General Standards: Basic Principles for Standardization and Calibration
JJF1001-2011 General Metrology Terms and Definitions ": Clarifying core terms such as calibration, standard substances, and indication errors is the fundamental framework for all metrological calibrations.
GB/T27025-2019 General Requirements for Testing and Calibration Laboratory Capability ": specifies the quality management system requirements for laboratory calibration, including personnel qualifications, environmental control (such as the impact of temperature and humidity on gas stability), etc.
JJF1071-2010 National Metrology Calibration Specification Compilation Rules: Guide the formulation of calibration specifications for various gas analyzers to ensure the uniformity of calibration processes for different instruments.
2、 Specialized calibration specifications for gas analyzers: subdivided by instrument type
Gas analyzers with different principles (such as infrared, electrochemical, and gas chromatography) have dedicated calibration standards, including:
JJG635-2011 Infrared Gas Analyzer for Carbon Monoxide and Carbon Dioxide: Suitable for infrared principle CO and CO ₂ analyzers, it specifies calibration indicators such as indication error (≤± 2% FS), repeatability (≤ 1%), response time (≤ 15s), etc., and specifies the need for high-purity standard gas (such as 1000ppmCO standard gas diluted with 99.999% N ₂) for point calibration.
JJG365-2008 Electrochemical Oxygen Analyzer ": For oxygen analyzers based on electrochemical principles, calibration items include zero drift (≤± 2% FS/4h) and range drift (≤± 2% FS/4h). Standard oxygen gas (such as 20.9% O ₂ air and 99.99% N ₂) is required to calibrate the zero and range.
JJG700-2016 Gas Chromatography Instrument: Suitable for gas chromatography gas analyzers, calibration content covers separation, sensitivity, repeatability, and requires mixed standard gases (such as standard gases containing methane and ethane) to verify the accuracy of retention time and peak area of each component.
HJ1077-2019 Determination of Volatile Organic Compounds in Waste Gas from Fixed Pollution Sources by Solid Phase Adsorption Thermal Desorption/Gas Chromatography Mass Spectrometry: For VOCs analyzers, it is stipulated that VOCs standard gases (such as mixed standard gases of benzene and toluene) are required for calibration, with a relative standard deviation (RSD) of ≤ 10%.
3、 Gas standard substance related standards: ensure the reliability of calibration gases
The quality of standard gas directly affects the calibration accuracy and must comply with:
GB/T5274-2018 Preparation and Weighing Method of Mixed Gases for Gas Analysis Calibration ": specifies the preparation method of standard gases, requiring an uncertainty of ≤ 1% (such as 100ppm SO ₂ standard gas, allowable error ≤ ± 1ppm).
JJF1343-2012 General Principles and Statistical Principles for Determination of Standard Substances: Ensure that the quantity of standard gases can be traced back to national standards, and the standard gases used for calibration must have certificates (indicating concentration, expiration date, and uncertainty).
4、 Application scenario related standards: Supplement calibration based on industry needs
In specific fields such as environmental protection and healthcare, calibration must meet industry standards:
In the field of environmental protection, the "HJ194-2017 Technical Specification for Manual Monitoring of Environmental Air Quality" requires that after calibration of the exhaust gas analyzer, the indication error must be ≤± 5%, and it must be compared with the standard methods of the national environmental monitoring network.
Medical field: According to YY/T0759-2018 Medical Oxygen Concentrator, the calibration of medical oxygen analyzers must comply with JJG365 and have an error of ≤± 3% within the range of 10%~95% O ₂.
summary
The core standards for calibrating gas analyzers are specialized metrological calibration specifications (such as JJG635, JJG365), supplemented by standard gas preparation standards (GB/T5274) and general metrological terminology standards (JJF1001). In practical operation, it is necessary to select corresponding standards based on the principle of the instrument and the application scenario, while ensuring that the standard gas used has a certificate issued by a legal metrology institution, in order to ensure the accuracy and traceability of the calibration results.