First, the definition and advantages of vacuum freeze drying:
Products through a total Freeze, and in the certain vacuum conditions make the sublimation, so as to achieve the purpose of the low temperature dehydration, this process is called freeze-drying herein after referred to as freeze-dried, the vacuum system as a part for vacuum freeze drying.
Lyophilized solid matter due to the sublimation of tiny ice crystals present porous structure, and keep the volume when previously frozen, after adding water to dissolve and recovery, products in the process of sublimation temperature keep in low temperature condition (usually less than – 250 – c), and for those who are not heat resistant material, such as enzymes, hormones, nucleic acid, blood and immune products particularly suitable for dry.Dry results can discharge more than 95% – 99% of the water, is advantageous to the long-term preservation of the product.Products drying process was conducted under the condition of vacuum, so it is not easy oxidation.For part of chemical, physical, biological, biochemical drugs instability, freeze-drying has been proved to be a very effective means.With the rapid development of biochemical drugs and biological agents, freeze-drying technology will more and more shows its importance and superiority.
Second, medical freeze drying machine structure and function of the abstract:
Medical freeze dryer system by the refrigeration system, vacuum system, heating system, electrical instrumentation control system.Main components for drying chamber, condenser, refrigeration units, vacuum pump heating/cooling devices, etc.
Rotary vane vacuum pump for pumping air into vacuum state, the system was installed in the mechanical pump inlet a solenoid valves with automatic deflated, it with the rotary vane pump is the same power control, when the pump stop, electromagnetic valve automatically shut down, at the same time inside the vacuum pump is deflated, both to protect the vacuum system, and prevent the vacuum pump oil return to the system.
Three, the basic principle of freeze-dried and practice
Requirements about the quality of the freeze-dried products are: biological activity remains the same, colour and lustre is uniform appearance and form full, firm structure, fast dissolving, low residual moisture.To get high quality products, the theory and process of freeze should have a more comprehensive understanding.Freeze-drying process including precool, sublimation and dry again frozen three phases.Reasonable surface effectively shorten the lyophilization cycle in the industrial production has obvious economic value.
Since the start of the vacuum system, all operation process can realize automatic control. during the work, in all parts of the vacuum system the vacuum degree (that is, the average distribution of the vacuum degree of thin) always fluctuates up and down in the permissible range, and its range can be adjusted according to the needs of users.Using screw vacuum pump, roots vacuum pump, rotary vane vacuum pumps and water ring vacuum pump vacuum system can achieve optimum process.