Freeze dryers are widely used in medicine, food and other industries. Taking lyophilization of medicines as an example, lyophilization of medicines includes two parts: traditional Chinese medicine and western medicine. In terms of traditional Chinese medicine, freeze-drying is mainly limited to lyophilization of a small amount of Chinese medicinal materials such as ginseng, velvet antler, and most Chinese patent medicines have not been subjected to freeze-drying. In the western medicine, especially the injection, the freeze-drying process is used more, which not only improves the quality of the medicine, but also prolongs the storage period.

The normal operation of the equipment is a prerequisite for ensuring good product performance. However, once the freeze dryer fails, it will seriously affect the production and bring some losses to the enterprise. Therefore, “preheating preparation” is essential before the freeze dryer operates. The author combines the experience of the industry to share the preparations that the freeze dryer needs to do before work.

Thoroughly clean equipment parts

The cleaning of the equipment is one of the conditions for ensuring no cross-contamination during work. Therefore, when using the freeze dryer for the first time, the industry stated that the parts of the equipment must be thoroughly cleaned.

Different parts cleaning conditions are also different. For example, stainless steel parts need to be cleaned with ethanol, plexiglass needs to be washed with physiological saline, and ampoules are cleaned with an ultrasonic cleaner.

Pre-freezing preparation

Pre-freezing must be carried out before freeze-drying. Pre-freezing needs to be prepared at a temperature of minus 40 ° C, or a low temperature refrigerator at minus 80 ° C. The items to be dried are placed in a low-temperature refrigerator or liquid nitrogen, which usually takes about four hours. Observed directly from the outside of the device. After the item is completely frozen in ice, the freeze-drying experiment can be carried out to quickly move the item into the freeze dryer tray to ensure the freeze-drying effect.

Check the air tightness of the equipment

The freeze dryer is connected to the vacuum pump by a green vacuum tube, and the joint uses international standard clamps. In order to effectively prevent air leakage, this type of clamp is specially designed with a sealing rubber ring in the clamp. In the method of preventing air leakage, it is recommended to apply a proper amount of vacuum grease on the rubber ring and then clamp it with a clamp to make the joints fit closer together.

If the clamp is not clamped, air leakage will occur, causing the display value of the instrument panel to be greater than 20pa when vacuum is drawn. At this time, the airtightness of the vacuum pump and the glass cover of the freeze dryer should be checked.

If the air tightness is not good, apply some vacuum grease to the sealing rubber ring above the cold trap, gently rotate the plexiglass cover on the rubber ring, and test the air tightness by opening the vacuum pump. To ensure the integrity of the gas seal.

Check vacuum pump oil before running vacuum pump

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 is necessary to check whether the vacuum pump oil is added, otherwise it will not operate normally. The oil level must not be lower than the center line of the oil mirror. The vacuum pump has a strong shaking when it is used at the beginning, and it will gradually become stable.

Dry the cold trap

In addition to the above "preheating" preparation, the industry said that it is necessary to remove the moisture in the cold trap chamber before the equipment is made, and dry the cold trap if necessary. Open the drain valve before each freeze-drying operation.

In addition, do not switch frequently during use. If the refrigerator stops running due to operational errors, it cannot be started immediately. Wait at least 20 minutes before starting again to avoid damage to the refrigerator. After lyophilization, the ice on the cold trap coil will be turned into water, which can be cleaned with a towel. After lyophilization, it is slow to unscrew the "inflation valve" to inflate the cold trap to avoid damaging the vacuum gauge.