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The Selection Principle Of Laboratory Freeze Dryer
Sep 12, 2017



The selection principle of Laboratory Freeze Dryer

The scientific and reasonable structure design of the Laboratory Freeze Dryer, the external type is novel, beautiful and generous, the operation, maintenance, maintenance is convenient, the installation is simple (without foundation). The cold system and air system of the Laboratory Freeze Dryer system are calculated by combining the experts with different working conditions in different parts of the country. The design parameters are more than 20%. Laboratory Freeze Dryer has been widely used in chemical industry, biological products and other fields. The Laboratory Freeze Dryer is in the leading position in the world refrigeration industry.
The selection of Laboratory Freeze Dryer should be considered according to the cold load and use. For the cooling system with long working conditions of low load, it is appropriate to select a multi-head piston compressor or screw compressor unit for easy adjustment and energy saving. The main control parameters of the Laboratory Freeze Dryer are the performance coefficient of refrigeration, rated refrigerating capacity, input power and type of refrigerant.
The conditions of nominal working conditions should be paid attention to when choosing a Laboratory Freeze Dryer. The actual cooling amount of the Laboratory Freeze Dryer is related to the following factors:
A) water temperature and flow rate of cold water;
B) water inlet temperature, flow rate and fouling coefficient of cooling water.
When choosing a Laboratory Freeze Dryer, the unit with high performance coefficient is preferred. According to the statistics, the operating time of the freeze-drying machine in the general laboratory is about 1/4 of the total operating time during the whole year. The operating time ratio of 100%, 75%, 50% and 25% of total operating time was roughly 2.3%, 41.5%, 46.1%, 10.1%. Therefore, it should give priority to the model of the efficiency curve when choosing the Laboratory Freeze Dryer. At the same time, the adjustment range of the Laboratory Freeze Dryer should be considered in the design selection. The multi - head screw - type refrigerating unit has excellent load performance, which can be selected according to the actual situation. Secondly, it should pay attention to the normal working range of the refrigeration dryer of this model, mainly the current limit of the main motor is the current value of the shaft power under the nominal working condition.
Should be paid attention to in the design: under nominal working condition of flow rate, outlet temperature of cold water should not be more than 15 ℃, outdoor dry bulb temperature of air cooling unit should not be more than 43 ℃. If you have to exceed the above range, you should know whether the use range of the compressor is permissible and whether the power of the main motor is sufficient.
Laboratory Freeze Dryer is a kind of use of the principle of sublimation drying technology, the material will be dry water cut in advance under low temperature quick frozen into a solid, and then in the appropriate vacuum environment, make frozen water molecules directly sublimate water vapour to escape to remove moisture and save material process.
In order to ensure the quality, and biological activity of samples need to precool the samples, in the refrigerator or lab after finish precool freeze drier in the freeze-dried warehouse shelf, in the main drying process of the sample. The moisture in the sample is directly sublimated by the low temperature and high vacuum of the Laboratory Freeze Dryer and the steam is captured by the cryogenic cold trap and vacuum pump. After dozens of hours after drying, for the most part of water sample by sublimation, and samples will be retained complete, sublimation of the gas in the cold trap sublimation of ice, due to the pressure, there are gas distillation constantly and then in the cold trap ice, ice during sublimation to absorb heat, cause the sample temperature drop and slow speed of sublimation, in order to increase the speed of sublimation, shorten the drying time, heating products must be properly. In order to ensure that the sample of higher purity, at this time the samples can be to heat up freeze-dried can also be called after drying process, the sample temperature to room temperature, lab freeze-drying machine all the lyophilization process is complete.
Operation process of Laboratory Freeze Dryer:
Turn on the quick filling valve of the Laboratory Freeze Dryer and turn off the vacuum pump power switch to slow the air into the cold hydrazine. If inert gas is to be charged, the decompression catheter of the inert gas is connected to the "inflatable port".
Close the "vacuum key" and "refrigerating key" of the Laboratory Freeze Dryer, such as long time no need to unplug the power cord;
The organic glass cover is brought up and the items are removed, preserved and frozen and dry.
When the ice in the cold trap is turned into water, the water must be removed from the quick filling valve port. The operation of the Laboratory Freeze Dryer is similar to that of inflation. (if the defrost function is available, press the defrost key to accelerate the dissolution.

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