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When purchasing a vacuum freeze dryer, you can mainly refer to the following aspects:
1. Freeze-drying area The number in the freeze-drying machine model represents the freeze-drying area of ​​the freeze dryer. For example, the freeze-drying area of ​​the LGJ-18C freeze dryer is 0.18 m2. The user should calculate the lyophilizer for the lyophilized area according to his own needs. For example, for each batch of products that require lyophilization of 1.8 kg (liter) of liquid, and loading the material with a material tray, each loaded with 10 mm thick, the load area of ​​the lyophilized layer can be calculated:
A (area, m2) = V (volume, m) / H (height, m) = 0.0018 m / 0.01 m = 0.18 m2
A lyophilizer with a lamellar load area of ​​0.18 m2 is required.
2, cold trap temperature cold trap is a device for capturing moisture in the freeze-drying process. Theoretically, the lower the cold trap temperature, the stronger the water trap capacity of the cold trap, but the cold trap temperature is low, the refrigeration requirements are high, the machine cost and operation costly. The cold trap temperature of the experimental series freeze dryer mainly has several grades of about -45 °C, -60 °C, and -80 °C. Freeze-drying at -45 °C for some freeze-dried products, freeze-drying machine with a cold trap temperature of -60 °C for lyophilization of most products, freeze-drying at -80 °C Suitable for lyophilization of some special products. The effect of cold trap temperature on water-trapping capacity shows that the temperature of the cold trap drops from -35 °C to -55 °C, and the water-trapping capacity is obviously improved. The cold trap temperature is lower than -55 °C, and the water trapping capacity of the cold trap is not significantly improved. Therefore, in the absence of special needs, the choice of cold trap temperature -60 ° C is the ideal choice. The cold trap temperature of the LGJ-10D freeze dryer in the four-ring freeze dryer is ≤-55 °C, and the freeze dryer temperature of the LGJ-18 series and LGJ-25 series is ≤-60 °C, and the refrigerant is mixed with mixed refrigerant. The technology, in the case of the same refrigeration unit, has a low cooling temperature, a large cooling capacity, a high operational stability, and a low failure rate. The four-ring lyophilizer also includes the LGJ-10 freeze dryer with cold trap temperature ≤ -45 ° C, suitable for lyophilization of some freeze-dried products. The cold trap temperature of LGJ-50C freeze dryer is ≤-80 °C, which is especially suitable for lyophilization of medicines and special products.
3. Cooling rate The cooling rate reflects the cooling capacity of the refrigeration system. Under no-load conditions, the temperature of the cold trap should reach the minimum temperature specified in the index within 1 hour. For example, a lyophilizer with a cold trap temperature ≤ -60 ° C, the machine starts from the time of opening the refrigeration, and the cold trap temperature reaches -60 ° C for no more than 1 hour.
4. Ultimate vacuum The ultimate vacuum reflects the leakage of the freeze dryer and the pumping efficiency of the vacuum pump. The degree of vacuum of the freeze-drying box, the past view that the higher the degree of vacuum, the better, the industry's view that the degree of vacuum should be within a reasonable range. The degree of vacuum is too high, which is not conducive to heat transfer, but the drying speed is reduced, but the vacuum limit of the freeze-drying box should reach 15Pa or more.
5, vacuum pumping time The emptying speed of the freeze-drying box should be pumped from atmospheric pressure to 15Pa within half an hour.
6, the layer temperature uniformity and flatness:
The uniformity and flatness of the lamellar temperature have a great influence on the uniformity of product quality. The better the temperature uniformity and the flatness, the better the uniformity of the quality of the freeze-dried product. The lyophilizer shelf temperature control has a heater type and an intermediate fluid type, and the freeze-drying machine shelf with the intermediate fluid control plate layer has uniform temperature uniformity and flatness, and the lyophilizer layer is a hollow sandwich structure, the slab layer The cooling and heating are achieved by circulating the intermediate fluid in the fluid channel inside the ply, so the temperature of the ply is uniform. The LGJ-50C freeze dryer in the four-ring freeze dryer uses the technology of the intermediate fluid in the shelf. The shelf temperature control of the bell-type lyophilizer is basically a heater, and the temperature uniformity of the plate layer is slightly poor. However, in general, the temperature difference of the lyophilizer for medical use should be controlled at ±1.5 °C, the temperature difference within the plate is ±1 °C, and the food freeze dryer can be appropriately relaxed.
7. Control system The type and function of the control system of the freeze dryer are different. For the freeze dryer of the experimental series, it is mainly used for the lyophilization process of materials and a small amount of trial production. Therefore, the control system should display the parameters of the freeze-drying process in real time and record automatically; set, modify and effectively execute the freeze-drying process program; have a communication interface to facilitate data collection and storage.
Vacuum Freeze Dryer Selection Guide
The vacuum freeze dryer is suitable for drying high-grade raw materials, Chinese herbal medicines, biological, wild vegetables, dehydrated vegetables, food, fruits, chemicals, pharmaceutical intermediates and other materials. Freezing vacuum drying is a new type of box structure that combines the refrigeration system, vacuum system, heat transfer oil heating system and dehumidification system into a vacuum freeze dryer. It uses the freezer vacuum drying to store the material space in the box.
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