In scenarios such as gas detection calibration and environmental monitoring standard gas preparation,Gas diluterThe cleanliness and airtightness of the pipeline directly determine the accuracy of the dilution ratio, which is the core prerequisite for reliable experimental data. The following is a pipeline cleaning process and airtightness testing plan that is suitable for industrial and laboratory scenarios, taking into account operational standardization and compatibility with domestic equipment. The overall process can be divided into two modules: "step-by-step cleaning" and "layered leak detection".

1、 Pipeline cleaning: from "basic impurity removal" to "deep residue removal"

Impurities, oil stains, or residual gases from previous experiments in the pipeline can cause cross contamination of diluted gas components. Cleaning should be completed in three steps: physical cleaning, chemical purification, and blow drying.

1. Physical cleaning to remove particles and impurities

For new pipelines or old pipelines with severe dust accumulation, first remove the pipeline joints and use clean nitrogen gas to blow the pipeline in reverse at a pressure of 0.3 MPa. Use the impact force of the airflow to remove particles and impurities such as dust and metal debris attached to the inner wall; If there is stubborn scale in the pipeline, the pipeline can be immersed in 5% neutral detergent solution for ultrasonic cleaning for 15 minutes, and then repeatedly washed with deionized water until the effluent is free of foam, so as to avoid the corrosion of the pipeline caused by residual detergent.

2. Chemical purification to remove organic residues

Chemical purification is required for pipelines used for diluting organic gases. Connect the pipeline to a dedicated cleaning device, and circulate a diluted anhydrous ethanol (or isopropanol) solution for 30 minutes to dissolve the organic oil stains on the inner wall of the pipeline; For special corrosive gas residues, corresponding neutralizing solutions (such as dilute sodium bicarbonate solution for acidic residues) can be used for passivation treatment to ensure that there are no active residues in the pipeline.

3. Blow drying to prevent secondary pollution

The cleaned pipeline needs to be dried to prevent water vapor from affecting the gas ratio. Connect dry nitrogen or inert gas and continuously blow at a pressure of 0.2MPa for 2-3 hours until the dew point meter at the outlet of the pipeline shows a water vapor content below -40 ℃; For precision pipelines, a hot air drying device (temperature ≤ 60 ℃) can be used to accelerate drying and avoid high temperature damage to pipeline seals.

2、 Airtightness testing: from "atmospheric pressure initial inspection" to "negative pressure precision inspection"

Failure of airtightness can lead to dilution gas leakage and imbalanced ratio. It is necessary to investigate according to the principle of "segmented detection and step-by-step pressurization" and adapt to different pressure levels of domestic productsGas diluter.

1. Initial inspection of atmospheric soap bubbles

Firstly, apply specialized leak detection soap solution to each joint of the pipeline, introduce 0.1MPa nitrogen gas into the pipeline and close the outlet valve. Observe whether continuous bubbles are generated at the joint. If bubbles appear, it indicates that the joint is not tightly sealed and needs to be re tightened or replaced with a new sealing ring; If there are no bubbles, proceed to the next step of fine inspection, which can quickly locate obvious leakage points.

2. Negative pressure holding precision inspection

For high-precision experimental scenarios, negative pressure leak detection is required. Connect the pipeline to a vacuum pump, draw the pressure inside the pipeline to -0.08MPa, and turn off the vacuum pump. Turn on the equipment pressure monitoring system and maintain the pressure for 30 minutes. If the pressure rebound value is ≤ 0.002MPa, it indicates that the pipeline's airtightness meets the standard; If the threshold is exceeded, it is necessary to block the pipeline section by section and repeat the inspection. After locking the leaking pipeline section, replace the damaged pipeline or seal.

3. Final inspection of standard gas verification

Finally, introduce a known concentration of standard gas and connect the outlet of the pipeline to a gas detector to observe whether the concentration value is stable. If there is no fluctuation in the value and it is consistent with the concentration of the standard gas, it indicates that there is no hidden leakage in the pipeline and it can be put into use; If the value continues to decrease, it is necessary to investigate the minor leaks in the pipeline welds or joints again.

In daily maintenance, it is recommended to conduct a comprehensive cleaning and leak detection of the pipeline once every quarter. DomesticGas diluterCan be paired with original factory specific cleaning kits to reduce maintenance costs while ensuring long-term stable operation of the equipment.