Floor Type Freeze Dryer What are the indicators to be consulted?
Freeze-drying is a method in which an aqueous substance is preliminarily frozen into a solid state, and then the water therein is sublimated from a solid state into a gaseous state under vacuum to remove the water and preserve the substance. The articles obtained by the drying method have the original chemical and biological properties, are easy to be preserved for a long time, can be restored to the form before lyophilization after adding water, and can maintain their original biochemical characteristics, which is a high-quality drying. method.
1, freeze-dried area
The number in the floor type Freeze Dryer model represents the freeze-dried area of ​​the floor type Freeze Dryer. For example, the LGJ-18C floor type Freeze Dryer has a freeze-dry area of ​​0.18 m2. The user should calculate the floor type Freeze Dryer to be used according to his own needs. For example, for each batch of products that require lyophilization of 1.8 kg (liter) of liquid, and load 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, m3) / H (height, m) = 0.0018m3 / 0.01m = 0.18m2
A floor type Freeze Dryer with a laminar load area of ​​0.18 m2 is required.
2, cold trap temperature
The cold trap is a device for capturing moisture in the freeze-drying process. Theoretically, the lower the temperature of the cold trap, the stronger the water trapping ability of the cold trap, but the lower the temperature of the cold trap, the higher the requirements for refrigeration, the higher the machine cost and the running cost. 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, floor type Freeze Dryer with a cold trap temperature of around -60 °C for most products freeze-dried, cold trap temperature -80 °C Dry is 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 trap 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 floor type Freeze Dryer uses mixed refrigerant refrigeration technology. In the case of the same refrigeration unit, the cooling temperature is low, the cooling capacity is large, the working stability is high, and the failure rate is low. The four-ring floor type Freeze Dryer also includes the LGJ-10 freeze dryer with a cold trap temperature ≤ -45 ° C 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 cold trap temperature should reach the low temperature specified by the index within 1 hour. For example, for a floor type Freeze Dryer with a cold trap temperature ≤ -60 ° C, the machine should start timing when the refrigeration is turned on, and the cold trap temperature should be -60 ° C for no more than 1 hour.
4, the ultimate vacuum
The ultimate vacuum reflects the leakage of the floor type 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 current 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 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. Floor type Freeze Dryer shelf temperature control with heater type and intermediate fluid type, floor type Freeze Dryer with intermediate fluid control plate layer. Temperature uniformity and flatness. This floor type Freeze Dryer plate layer is a hollow sandwich structure. The cooling and heating of the lamellar layer 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 Song type floor type Freeze Dryer uses the technology of the intermediate fluid in the shelf. The shelf type of the bell type Freeze Dryer is basically a heater, and the temperature uniformity of the layer is slightly poor. However, in general, the temperature difference of the floor type Freeze Dryer for medical use should be controlled at ±1.5 °C, the temperature difference within the plate is ±1 °C, and the food floor type Freeze Dryer can be appropriately relaxed.
7, control system
Floor type Freeze Dryer's control system has different types and functions. For the floor type Freeze Dryer of the experimental series, it is mainly used for lyophilization 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.