What are the preparations for the freeze dryer before work？
The freeze dryer must be pre-frozen before being used. Pre-freezing requires a low-temperature refrigerator, a temperature of minus 40 degrees Celsius, or a low-temperature refrigerator of minus 80 degrees Celsius. The dry-prepared items are placed in a low-temperature refrigerator or liquid nitrogen. For about four hours, it can be observed directly from the outside. After the item is completely frozen, the freeze-drying experiment can be carried out to quickly move the item into the freeze dryer tray to ensure the freeze-drying effect.
The main unit and the vacuum pump are connected by a green vacuum tube, and the joint uses an international standard clamp. In order to effectively prevent air leakage, this type of clamp specially designed a sealing rubber ring in the clamp, apply a proper amount of vacuum grease on the rubber ring, and then clamp it with a clamp to make the joint fit more tightly. Together, it effectively prevents air leaks. If the clamp is not clamped, air leakage will occur, resulting in a digital display value greater than 20 Pa when the vacuum is drawn. At this time, the airtightness of the vacuum pump and the glass cover of the freeze dryer should be checked.
There are two power sockets on the right side of the freeze dryer main unit. One connects the power line of the vacuum pump to the main unit, and then plugs the main power supply on the second freeze dryer into the power supply.
Before the vacuum pump is running, it must be checked whether vacuum pump oil is added, otherwise it will not operate normally. The oil level should not be lower than the center line of the oil mirror. When the vacuum pump is used, it has a strong shaking, and it will gradually become stable.
If the air tightness is not good, apply some vacuum grease to the sealing rubber ring above the cold trap, spin the plexiglass cover on the rubber ring, and test the tightness by opening the vacuum pump. To ensure that its closure is complete.