Calibration of SF6 Gas Leak Detector: Is the Standard Gas Selected Correctly?

Calibration of SF6 Gas Leak Detector: Is the Standard Gas Selected Correctly?

In scenarios such as power equipment operation and maintenance, and industrial insulation detection, the accuracy of SF6 gas leak detectors is directly related to equipment safety and environmental protection. Calibration is the core link to ensure the performance of the instrument, and the selection of standard gas is the “soul” that determines the calibration effect. Only by choosing the right standard gas can the SF6 gas leak detector always maintain its “sharp eyes” and accurately capture every leakage hazard.

I. Core Composition of Standard Gas: Dual Assurance of Purity and Medium

The standard gas for calibrating the SF6 gas leak detector must meet the dual requirements of “high purity of the main component + compatible dilution medium”, which is the basis for ensuring calibration accuracy:

1. Main Component: High – purity SF6 Gas

As the reference substance for calibration, the purity of SF₆ gas must reach over 99.99% to avoid interference from impurities such as moisture, oil, and other fluorine – containing gases on the calibration accuracy. Low – purity SF6 may cause the sensitivity drift of the instrument, directly affecting the accuracy of the SF6 gas leak detector in judging leakage points.

2. Dilution Medium: Inert Gas Adapted to the Scenario

The standard gas needs to be diluted with inert gases such as dry air and nitrogen (N₂) to form mixed gases with different concentrations. For example:

The SF6 gas leak detector used for outdoor high – voltage equipment detection often uses dry air as the dilution medium to simulate the actual working environment;

For high – precision calibration in the laboratory, nitrogen is mostly used for dilution to reduce the impact of trace impurities in the air (for more details about the calibration environment, refer to “Guide for the Correct Use and Maintenance of SF6 Gas Leak Detectors” →).

II. Concentration Selection: Covering the Range and Precisely Matching Detection Requirements

The concentration of the standard gas needs to “fit perfectly” with the range of the SF6 gas leak detector to ensure the linear accuracy of the calibration curve, which is the key to improving calibration accuracy:

1. Low – Concentration Standard Gas (1 – 50μL/L)

Suitable for scenarios with extremely high detection accuracy requirements (such as micro – leakage detection of GIS equipment), it can calibrate the response ability of the SF6 gas leak detector to 0.01ppm – level trace leaks and avoid the hidden danger of missed detection.

2. Medium – Concentration Standard Gas (100 – 500μL/L)

Adapted to the routine detection needs of most industrial sites, covering the commonly used concentration range for daily leakage inspections, ensuring the accurate reading of the SF6 gas leak detector within its core working range.

3. High – Concentration Standard Gas (1000μL/L and above)

Used to calibrate the upper limit of the instrument’s range, verify the accuracy of the alarm threshold in case of high – concentration leakage, and ensure the safe response of the SF6 gas leak detector in emergency situations.

Key Principle: The concentration needs to cover the “minimum detection limit” to the “maximum range” specified in the instruction manual of the SF6 gas leak detector. For example, if the range of an instrument is 0 – 2000μL/L, then standard gases with multiple concentration points such as 50μL/L, 500μL/L, and 2000μL/L need to be used to draw a complete calibration curve.

III. Certification Requirements: Authoritative Endorsement to Ensure Traceability

The “legitimacy” of the standard gas directly determines whether the calibration results are recognized, which is an important guarantee for calibration accuracy:

1. Certification by Authoritative Institutions

It needs to pass national metrology certifications (such as CNAS in China [1], NIST in the United States [2], and CE in the European Union), and be accompanied by a complete calibration certificate clearly indicating key information such as concentration value, uncertainty (usually ≤ 2%), and validity period (12 – 24 months), ensuring that the data can be traced back to international standards.

2. Professional Storage and Shelf Life

The standard gas needs to be stored in a special high – pressure steel cylinder, avoiding direct sunlight, high temperatures, or severe vibrations. Before use, it is necessary to confirm that it is within the validity period. Expired gas may cause the calibration of the SF6 gas leak detector to fail due to concentration attenuation.

IV. Special Scenarios: The Necessity of Zero Gas and Multi – Concentration Combinations

1. Zero Gas Calibration is Indispensable

Before calibration, “zero gas” (pure nitrogen or dry and clean air, free of SF6 and interfering gases) needs to be used to correct the zero point of the SF6 gas leak detector to avoid the influence of the environmental background value. The SF6 residue in high – quality zero gas needs to be ≤ 0.1μL/L to ensure the accuracy of zero – point calibration.

2. Multi – Concentration Combinations Improve Reliability

For high – precision detection (such as laboratory – grade SF6 gas leak detectors), it is recommended to use a combination of 3 – 5 concentration points of standard gas to generate a calibration curve through linear fitting, reducing the error of single – point calibration, especially suitable for instruments with a wide range and high – precision requirements.

Choose the Right Standard Gas to Make Detection “Rule – Abiding”

The standard gas is the “calibration scale” of the SF6 gas leak detector. Its purity, concentration, and certification qualifications directly determine whether the instrument can accurately identify leakage hazards. Whether it is power operation and maintenance, industrial safety inspection, or environmental monitoring, choosing SF₆ standard gas that is authoritatively certified, concentration – adapted, and stored in compliance can make every detection “data – reliable and result – credible”, building the first line of defense for equipment safety and environmental protection.

If you need to further understand the selection and procurement of standard gases, you can contact professional gas suppliers (view recommended suppliers and product pages →) to customize an adapted solution according to the model of the SF6 gas leak detector and the detection scenario, making the calibration work efficient, accurate, and compliant.