The solid substances freeze-dried by the freeze-drying machine exhibit a porous structure due to the sublimation of small ice crystals, and maintain their original frozen volume. After adding water, they are easily dissolved and restored. During the sublimation process, the temperature of the product is maintained at a lower temperature, making it particularly suitable for those heat-resistant substances. The drying result can expel over 95% -99% of water, which is beneficial for the long-term preservation of the product. The drying process of the product is carried out under vacuum conditions, so it is not easy to oxidize. Freeze drying has been proven to be a highly effective method for addressing the chemical, physical, and biological instability of some biochemical drugs.

Knowledge of daily maintenance and upkeep of freeze-drying machines:

（1） Observe and record instrument values 4 times per shift

1. The pressure difference between the inlet and outlet of compressed air shall not exceed 0.035Mpa;

2. Evaporation pressure gauge 0.4Mpa -0.5Mpa;

3. High pressure gauge 1.2Mpa -1.6Mpa.

（2） Cold drying machines should regularly observe the drainage and sewage systems

1. Clean the floating ball drainage device about once a week;

2. The sewage pipe discharges water once a week.

Cleaning method for electronic drain:

a. Close the ball valve in front of the automatic drain;

b. Loosen the upper fixing nut and take out the timing coil. During the cleaning process, the coil should never come into contact with water, otherwise it will burn off;

c. Remove the hose, loosen the drain valve body, and vent the compressed air inside the drain;

d. Remove the valve core and wipe it clean;

e. Screw the valve body back to its original position, gently open the front ball valve a bit, and use compressed air to drain impurities, water, and oil from the drainage system; Clean the valve body with a cloth;

f. Install the valve core and timing coil back in place; Install the hose again and open the front ball valve.

（3） Regularly observe the inlet temperature of the cooling water system and compressed air system

1. Cooling water temperature 2-32 ℃;

2. Water pressure 0.15~0.3Mpa;

3. The intake temperature of compressed air should generally be ≤ 45 ℃ (it is advisable to touch the intake pipe with your hand and not burn it), except for special circumstances.

4. The cooling water should be kept clean, and the Y-shaped filter should be cleaned once every half month, with good water quality once a month; The water condenser is cleaned once a year (depending on the water quality), and the air condenser is cleaned once a month;