Column
Contents
Oil-sealed rotary vacuum pumps and dry vacuum pumps
Freeze-drying and hot air drying
Oil-sealed rotary vacuum pumps and dry vacuum pumps
There are two main types of vacuum pumps used in freeze-drying equipment: oil rotary vacuum pumps and dry vacuum pumps.
Oil-sealed rotary vacuum pumps
An oil-sealed rotary vacuum pump is a pump that uses oil inside to generate a vacuum. The oil is sealed and lubricates the internal mechanisms of the pump while it is operating.
【Features】
◆Relatively inexpensive to implement and highly efficient (easily reaches high vacuum).
◆Regular oil changes and cleaning are necessary, but on the other hand, oil changes often resolve problems.
Dry vacuum pump
A dry vacuum pump is a pump that does not use oil or liquid in the path for creating a vacuum, and there are several types depending on the pump structure.
【Features】
◆Compared to oil-sealed rotary vacuum pumps, the initial cost is higher, but running costs tend to be lower as frequent oil changes are not necessary.
◆It is clean because the exhaust does not contain oil.
Freeze-drying and hot air drying
Freeze-drying and hot-air drying are both methods of removing moisture from objects, but there are significant differences in their methods and characteristics.
Freeze-dried (lyophilized)
【Process】
First, freeze the object, then place it in a vacuum and allow the water to evaporate (sublimate) while still frozen.
【Features】
◆Low-temperature drying preserves the nutritional value, taste, and color of food and products.
◆Nutrients and flavor are retained, and it can be stored for long periods of time. The shape also remains close to its original state.
◆Processing takes time, and the equipment is expensive and costly.
Hot air drying
【Process】
Dry by blowing hot air onto objects to evaporate moisture.
【Features】
◆It can be dried quickly because moisture is removed using relatively high temperatures.
◆Short processing time, inexpensive equipment, and low cost.
◆High temperatures can cause loss of nutrients and flavor.