Standard gas calibratorThe usage method (taking Fourier transform spectrometer as an example)
Preparation before calibration
Tools and materials: Prepare high-purity nitrogen gas (for zero adjustment), standard gas with a concentration of 80% -100% of the equipment range (such as CO standard gas), fluorine tube, adjustable wrench, and calibration software.
Environmental conditions: Ensure that the laboratory temperature is between 15-30 ℃, the relative humidity is ≤ 70%, the instruments are placed horizontally and the power supply is well grounded, avoiding mechanical vibration, electromagnetic interference, and direct sunlight.
Equipment preheating: Before ventilation, the instrument needs to be preheated to ensure that it is in a stable working state.
Zero adjustment operation
Connect nitrogen: Connect high-purity nitrogen to the calibrated inlet of the equipment, with a stable flow rate of around 4L/min.
Wait for stability: After the data on the industrial computer stabilizes or is ventilated for 4-5 minutes, click the "Zero" button in the software.
Verification result: After successful zeroing, observe the absorbance curve to ensure that the baseline presents a horizontal straight line with a value of 0 within the range of 1500-5000cm ⁻¹ on the X-axis.
Calibration of standard gas
Connect standard gas: Connect the standard gas to be calibrated to the calibration inlet, ensuring that the concentration of the standard gas does not exceed the equipment range.
Concentration conversion: If the concentration unit of the standard gas is ppm, it needs to be converted to mg/m ³ and the converted concentration value should be filled in the software.
Spectral comparison: Click on the spectral icon in the software, select the corresponding standard gas, and check whether the fluctuation range of the standard absorbance curve is consistent with the measured absorbance curve. The deviation should be within a reasonable range.
Calibration verification and repeatability testing
Verification accuracy: By repeatedly measuring standard substances, calculate the relative error between the measured concentration and the standard concentration to ensure that it does not exceed the specified range (such as relative error ≤ 5%).
Repeatability testing: Conduct multiple repeated measurements on randomly selected samples (such as 10 consecutive measurements) to evaluate the repeatability and stability of the model (such as relative standard deviation<2%).
Post calibration processing
Gas path switching: After calibration is completed, switch the measurement gas path in a timely manner to avoid contamination of the instrument by the standard gas.
Record archiving: Detailed records of calibration dates, standard samples used, data comparison before and after calibration, and corrective measures taken to track changes in instrument performance and maintenance history.