leak detection of cryogenic Dewar

liquid oxygen, on-board natural gas, and cryogenic liquids. They are widely used in the production, storage, transportation, and use of liquefied gas. They are particularly important for the tightness of gas cylinders. Any leakage may cause The loss of gas, if the pressure vessel carries natural gas or flammable gas, is likely to cause an explosion hazard, so it is necessary for the leak detection of Dewar (welded insulated gas cylinder).
 
Dewar leak detection method: vacuum mode and positive pressure mode
Dewars (welded insulated gas cylinders) mostly use the negative pressure mode of the helium mass spectrometer leak detector, which is the vacuum mode leak detection. Connect the helium mass spectrometer leak detector to the vacuum system. Since the HLT550 does not have a foreline pump, you can use the site The vacuum system used as the foreline pump of the helium mass spectrometer leak detector is best connected near the air inlet (that is, the air inlet of the vacuum pump group).

The vacuum system will have the pump group pumping vacuum, so the pump Connecting the leak detector at the air inlet is in the direction of airflow movement, and it is easy to have a partial pressure divided into the leak detector, so as to achieve the effect of leak detection. Vacuum welding furnace using helium mass spectrometer vacuum mode detection is the most widely used pressure vessel detection method in the industry. Dewar (welded insulated gas cylinder) is evacuated by a vacuum system, and the leak detector is connected to the intake gas of the vacuum pump group At the end, because the air flow will go to the vacuum system, if there is a leak point of helium spray, it will pass through the exhaust port of the leak detector. After the helium mass spectrometer leak detector detects helium, there will be a change in the leak rate to reach the gas bottle Measuring effect of leak detection.