The vacuum system used in the Freeze-drying process

Vacuum system is composed of a vacuum vessel, vacuum pumps, vacuum valves, vacuum gauge, vacuum sealed, condenser and pipe combination according to certain requirements.

Basic requirements

(1) of the vacuum system

(a) freeze-drying of materials needed, should be able to reach a certain limit vacuum and vacuum work. Ultimate vacuum refers to a system that can be achieved when there is no leak minimum pressure; work is some sort of vacuum process can maintain vacuum.

(b) in the best possible conditions to increase the effective pumping speed, which can shorten the extraction time, reduce the cost of freeze-dried products.

(c) Simple system is to structure, solid, simple operation, easy maintenance.

(2) sealing vacuum system

There are two vacuum-sealed, permanently sealed first by a metal or ceramic or glass and metal welding achieved; the second is removable static seal and dynamic seal. Static sealing element is connected, sealed remain stationary; dynamic seal is the need to ensure that both the sport and also sealed.

Detachable vacuum seal, sealing material should have a joint flange element sandwiched in the middle of the pad, by squeezing, tightening a seal. Choose a different sealing materials upon request vacuum. Commonly used sealing materials: rubber, poly ethylene four atmosphere, soft metal, aluminum, oxygen-free copper and so on.

Vacuum grease used to coat from between two smooth flat vacuum sealing and lubrication. Vacuum sealing wax to fill a small leak on the vacuum system. Vacuum sealing wax mud into the vacuum and vacuum December categories.

(3) dry warehouse operations

Dry container is an important component of the vacuum system, the vacuum performance which affect the performance of the entire quality frozen in machine. It is a vacuum chamber, and a container of freeze-dried material.

(4) water trap

Water trap vacuum system is one of the container, its role is to capture material sublimation of water vapor, in order to protect the vacuum pump. Water trap, also known as trap, condenser and cold trap and so on.

(5) vacuum line and vacuum valve

In dry container and water trap, catching between water and the pump has some vacuum pipe, and a vacuum valve to control the opening and closing of the largest and small stream.

Vacuum valve valve according to the intensity of work can be divided into low vacuum valve, ultra-high vacuum valve and vacuum valve types, so choose the vacuum valve mainly by the use of occasions and conditions of use, the model size, the diameter of the pipe decision.

(6) vacuum measurement

The degree of vacuum pressure is generally used to indicate, therefore, due to the vacuum test pots on the measurement of the pressure in the vacuum environment. Vacuum Technology vacuum measurement is obtained with vacuum as important and closely related parts. The traditional method is a direct measurement of vacuum pressure measurements, for example, U-shaped tube vacuum gauge (eg a McLeod gauge) I measured the vacuum, there is still used, but it does not apply to the environment and automation systems containing condensable gas molecules. The level of the substance is its degree of vacuum of human small molecular number density, and size of the number density of gas molecules has its own physical characteristics, such as thermal conductivity, electrical conductivity, etc., based on these characteristics to design many kinds of vacuum gauges.

Freeze dry operating system gas pressure range is generally 105-1Pa, but often contain water vapor, oil vapor and other condensable gases, often accompanied by changes in the temperature and equipment around the uneven temperature, there is the process in some non-steady gas directional flow. So pay attention to the actual process conditions and their impact on the measured value when selecting a vacuum gauge and measured.

Freeze-drying process for the application of vacuum gauges have a McLeod gauge, thin film vacuum gauge, vacuum gauge resistance, such as ionization vacuum gauge.