The document describes the principles and process of freeze drying. Freeze drying works by sublimating ice under low temperature and pressure below the triple point. The process involves pre-freezing materials, primary drying where ice sublimates under vacuum, secondary drying to further remove moisture, and sealing in packaging. Freeze drying is useful for heat-sensitive materials as it avoids heat degradation and allows for sterile and moisture-controlled products. However, it is a time-consuming and expensive process.

1. FREEZE DRYER
PRINCIPLE
Drying by sublimation-triple point-temp. & pressure below triple point.
Drying chamber in trays.
Heating coils.
Vapor condensing or adsorption system with refrigerator.
Vacuum pump.
01. Preparation & pretreatment: Vacuum ay vacuum tray dryers.
02. Pre-freezing for solidifying water: Cold (-50 C)
03. Primary drying [sublimation of ice under vacuum] =
At 0.0098 degree C & 0.533 kilopascals.
Temperature is increased to 30 degree C within 2 hours.
The temperature kept constant. Around 98 to 99% water is removed.
04. Secondary drying (removal of moisture at high vacuum): Temp. as 50 to 60 degree C & low
vacuum.
05. Packing: Air replace with gas & seal.
CONSTRUCTION
WORKING

2. USES
❑ For production of dosage forms as injections, suspensions.
❑ blood plasma & blood products.
❑ Human tissues.
❑ Antibiotics & plant extracts.
• Suitable for thermo-labile materials.
• Loss of volatile is less.
• No migration occurs.
• Sterile maintains.
• Suitable for moisture sensitive materials.
 High costs.
 Time consuming.
 Oxidation may occur.
 Volatile compounds may be removed by high vacuum.
ADVANTAGES
DISADVANTAGES