How to maintain the vacuum freeze dryer?

The working principle of the vacuum freeze dryer is to freeze the material so that the contained water becomes ice, and then the ice is sublimed under vacuum to achieve the purpose of drying.

How to maintain the vacuum freeze dryer? Please note the following two points:

1. Maintenance of Vacuum Freeze Dryers in Use

Prepare the sample as much as possible to increase its surface area, which must not contain acid-base substances and volatile organic solvents. The sample must be completely frozen to ice, and any residual liquid can cause vaporization. Note that the cold trap is about minus 65 degrees and can be used as a low temperature refrigerator, but insulation gloves must be worn to prevent frostbite. Before starting the vacuum pump, check whether the outlet valve is tightened and the inflation valve is closed. The contact surface between the organic glass cover and the rubber ring is clean and free from dirt and is well sealed. Under normal circumstances, the aircraft shall not be used continuously for more than 48 hours. During the freezing process of the sample, the temperature gradually decreases, the sample can be taken out and warmed up for a period of time (still in a frozen state), and drying is continued to shorten the drying time. Liquid crystal display, Chinese interface, with sample drying curve. Imported compressors, with additional heat exchangers, increase the cooling capacity and increase the catching capacity. Large cold trap opening, no inner coil, with sample pre-frozen function. The pre-cooled rack can be used as a guide barrel to speed up drying. The cold trap and operating surface are all stainless steel, corrosion-resistant and easy to clean, transparent bell jar. Transparent bell-type drying room, safe and intuitive. Stainless steel sample holder, ordinary sample tray spacing adjustable. The design is novel, the size is small and the operation is convenient, and the occupation of the laboratory bench is reduced. Optional nitrogen gas filling valve.

2. Maintenance of Vacuum Freeze-Dry Mechanical Switching Machine

Open the main power switch on the left side of the vacuum freeze-drying machine chassis, and the air pressure is displayed at atmospheric pressure 110 pk. Press and hold the key on the control panel for more than three seconds. The temperature is displayed as the actual temperature of the cold trap. Start the refrigerator and precool it for more than 30 minutes. Place the sample in the sample holder, cover the plexiglass cover, and start the vacuum pump. After the pressure is stable, record the temperature and pressure values. Record the temperature and pressure values ​​before the vacuum freeze-drying machine shuts down. Press and hold the inflation valve on the control panel and immediately close the vacuum pump. When the atmospheric pressure is at atmospheric pressure, open the plexiglass hood and remove the sample. Turn off the refrigerator, press and hold the key for more than three seconds, and finally turn off the main power switch. After the ice in the cold trap is completely turned into water, open the outlet valve on the left side of the cabinet to drain the water, clean the inner wall of the cold trap with a dry cloth, and cover the large filter paper to prevent dust.