Gas chromatograph is an instrument used for gas chromatographic separation and analysis. Its basic components include: carrier gas control, regulation system (providing stable pressure and flow phase), sample injection system, separation system (column), detection system, signal recording, processing system and temperature control system. According to the needs of the analysis task, various chromatograph systems can be effectively combined into different systems, such as mechanical control and electronic control. Injection can be manual/automatic or split/no split, packed column, preparation column or capillary column can be used to detect different types of detectors. The signals are recorded and processed using a potentiometer, integrator, chromatography workstation.

The experimental results show that under the carrier gas condition of TCD detector, when the fluctuation amplitude of hydrogen is 0.05 ml/min, the baseline of FID detector has obvious drift. Therefore, the gas flow stability of the gas chromatograph is very important for the mechanical valve or EPC gas circuit.

Considering the discontinuity between various sensors, the instrument manufacturer adopts the fitting method to fit the measurement method of the response curve of various gases to the sensor, and uses the flow correction algorithm in the instrument design to calibrate the flow sensor in the production process. Therefore, when measuring the stability of the instrument carrier gas, the medium and low flow rates and high flow rates should be selected, and the large flow rate should be used as the calculation result of the stability of the carrier gas.

A gas chromatograph is typically used to measure the gas flow at the detector outlet. Soap film flowmeter is a typical measuring tool. Soap film was formed in a standard measuring tube with soap solution. When the measured gas enters the measuring tube, the soap film is pushed into the measuring tube, and the air flow generated by the moving position of the soap film in the measuring tube per unit time is calculated. The method is simple, intuitive and accurate, and can be widely used in the detection of small gas flow. Due to the formation of soap film, the calculation time is long, and multiple measurements are required to eliminate the error.

In addition, derived from the formula, in some cases, the difference between the corrected flow rate and the flow rate before correction is 10 ml/min, which has a great influence on the detection results. Therefore, it is very important to correct the carrier gas flow rate, especially when the critical value of the data is on the edge of the verification conclusion, carefully calculate and repeatedly check the room temperature, air pressure and other data at that time.