Liquefied gas cylinders are filled with liquid at low temperature when filling. The critical temperature of some liquefied gas is low, and it is vaporized in the bottle after being affected by the ambient temperature. The critical temperature of some liquefied gases is high, and the liquid vapor equilibrium is always kept in the bottle after bottling, so it can be divided into high pressure liquefied gas and low pressure liquefied gas.

(1) high pressure liquefied gas. The critical temperature is greater than or equal to of-10 DEG C, and less than or equal to 70 DEG C. Common ethylene, ethane, carbon dioxide, oxidative xenon, six sulfur hexafluoride, hydrogen chloride, three fluorine methane (F - 13), three fluorine methane (F - 23), six fluorine ethane (F - 116), fluorine and so on. The common filling pressure is 15MPa and 12.5MPa.

(2) low pressure liquefied gas. The critical temperature is more than 70 degrees centigrade. Such as hydrogen bromide, hydrogen sulfide, ammonia, propane, propylene, isobutene, 1, 3- butadiene, 1- butene, ethylene oxide, liquefied petroleum gas and so on. According to the safety supervision regulation of gas cylinders, the maximum working temperature of liquefied gas cylinders is 60 degrees centigrade. The saturated vapor pressure of low pressure liquefied gas at 60 degrees is below 10MPa, so the filling pressure of this kind of gas is not higher than 10MPa.

Natural gas is not able to be filled in liquefied gas cylinders, and natural gas liquefaction is formed by low temperature compression. Under the same environmental conditions, the saturated pressure of natural gas is much higher than that of liquefied gas, and the liquefied gas cylinder is unsafe. Typically, natural gas (pure methane) is installed in similar hydrogen cylinders of liquefied gas bottle, and installed in the liquefied gas cylinders in general, pressure, general pure methane bottle pressure is 13MPA, is 130 kg, while the liquefied gas is generally 0.5MPA, is 5 kg.

During the filling process, filling member to use portable combustible gas alarm and spray test vehicle joints and other parts for valves and gas cylinders, if leakage occurs, should immediately stop filling, to push the vehicle to a safe place outside the station to repair is completed, after testing without leakage after restore with gas. If you can hear the sound of natural gas flow in this process, and should pay attention to observe the filling machine, inflatable valve and filling car inflatable valve whether there is condensation, abnormal sound. In case of abnormal phenomena, gas should be stopped immediately, and the gas can be recovered after troubleshooting.

When the working state lamp of the filling machine indicates that the gas is finished, the charging valve of the inflator is closed, the inflating valve is turned off, and the emptying valve is opened after the emptying valve is emptied, and the dust plug is inserted. Remove the safety hook.