The device needed in cryodesiccation or freezing certain material is widely known as freeze dryer. The process of dehydration that is mostly used in the preservation of fragile material is called cryodesiccation. The process of freeze-drying makes the material more suitable for transporting. Freeze-dryer helps in freezing materials and then reducing the pressure to allow the frozen water to change from solid to gas state directly. The first freeze-dryer helped in the development of anti-rabies vaccine by making the live rabies virus freeze.
Contemporary freeze-drying technique was developed during second world wars phase. This technique is now used as a commercial technique. It has been used as preservation method for a large variety of products like food, diagnostic kits, manufacturing ceramics, produce synthetic skin, restoration of water damaged documents, pharmaceuticals.
Vacker KSA supplies a wide range of freeze dryers in many cities of Saudi Arabia like Riyadh, Al Khobar, Dammam, Jeddah, etc. These air dryers are very reliable and efficient.
Stages of Freeze-drying
The freeze dryer helps in four stages of freeze drying. These are discussed below:
It is the method of treating the product before freezing. This includes formulation revision, the concentration of the product, and reduction of solvents that have a relatively high vapor pressure. Product quality consideration and cycle time may determine the pretreatment of the products.
A freeze dryer used in the labs by placing a material, that needs to be frozen, in a freeze-drying flask and the same flask is rotated in a bath, which is cooled with the application of mechanical refrigeration. This is called the shell freezer. If you need to go in a relatively larger volume of lyophilization then we offer you with heavy duty large industrial freeze drying machines. In this stage of freeze drying, the materials need to be cooled below their triple point (a triple point is a point of an element is the pressure and temperature at which all the 3 states of that element co-exist, under thermodynamic equilibrium).
At the stage of primary drying, the pressure is generally lowered to few millibars only. However, the right amount of heat is maintained to the material so that the ice sublimes. The exact amount of heat that is required to do so is calculated by using the latent heat of sublimation of the sublimating molecules. In the primary drying phase, almost 95% of the water content of the material is sublimated. This is a very slow stage and might take up to several days so that there is no temperature fluctuation resulting to alteration in the shape of that material.
This is called the secondary drying stage which aims in removing the water molecules that are not frozen even after the primary drying stage. However, the ice is removed in the primary stage, itself. The material’s adsorption isotherm determines the secondary drying process. The temperature level is raised in comparison to the primary drying phase in order to break the physiochemical interaction established between the frozen material and the water molecules present. Sometimes, the temperature level rises above 0-degree centigrade. In reverse to the temperature, the level of pressure is decreased in this stage of freeze drying. The pressure level is lowered to as low as few microbars and this is done in order to encourage desorption.
Applications of Lyophilizer and Freeze Dryer
Lyophilizers and freeze dryers can be applied in various fields. Some of the common fields of application have been mentioned as below:
- Pharmaceutical and biotechnology
- Food and agriculture-based industries
- Technological industry
- Other uses (These processes are used in the recovery of books and documents that were once damaged by water. It is also used in advanced ceramics and for floral preservations. Dead bodies are also preserved with its help)