Vacuum oven is a special type of oven. This is suitable for the drying of the heat sensitive materials. The main advantage of vacuum oven is that it helps to accelerate the rate of drying. Similarly, the process of drying can be done at a lower temperature. This is specially suitable for the heat sensitive materials. Also, it is an oxygen deficient processing method. So due to these superior properties, we will be discussing the working principle, design, operation and the handling process of the machine.
Also, we will discuss the contact details of the supplier for you to purchase the vacuum oven (vacuum dryer) in Nepal.
Vacuum Oven Principle
Vacuum oven operates by lowering the pressure of the operating environment.
We know that, there is a direct relationship between the atmospheric pressure and the boiling point. That means, when the pressure is decreased, the boiling point will also decrease and vice versa.
When the boiling point decreases, the water quickly evaporates. The evaporation of the water causes decrease in the temperature of the wet object. Thus to maintain the temperature of the object, the chamber is heated.
(Note:- The evaporation is the process in which the water molecules having higher kinetic energy escape the surface of the water and mixes with the atmosphere. Thus the overall kinetic energy of the water molecules decreases. This leads to the drop in the temperature of the liquid water. )
Also, the flow of higher velocity of dry air within the chamber accelerates the rate of drying. Thus in conclusion, higher temperature, velocity of dry air and lower chamber pressure are responsible for the process of vacuum drying.
Design : Vacuum Oven
The diagram shown above is an example of digital system of vacuum dryer. In this system, the oven connects to an external three-pin power socket. From the power socket, the live wire goes to the PID controller and the SSR through the fuse and switch. Then the connection goes to the heating coils. The heating coils surround the inner chamber of the vacuum oven. The mains indicator is used to indicate the condition of power from the external supply. Similarly, the heating indicator is used to indicate the condition of the heating coils.
The heating coils are surrounded by the glass wool from all the sides. The glass wool acts as an insulator for preventing the loss of heat into the surrounding.
The outer cover of the machine is generally made up to stainless steel. This allows to sustain higher pressure and temperature.
The PID controller and the solid-state relay (SSR) are responsible for controlling the heating of the heating coil. When the temperature of the inner chamber of the vacuum oven is lower than that of the set value, the controller will supply a certain DC voltage to the relay. Then the relay will get activated causing the flow of AC current to the heating coils. Thus the coil begins to heat the side compartments. Finally, the heat is radiated to the inner chamber.
When the actual temperature of the air goes closer to the set value, the PID controller will activate and deactivate the relay simultaneously. Thus the heating coils will go ON/OFF continuously. So, by controlling the duration of the ON and OFF stage, the vacuum dryer helps to maintain an almost accurate result with not more than 2°C of variation.
The resistance temperature detector (RTD) such as the PT100 sensor, senses the temperature of the air. Then, it converts the temperature to the resistance value and supply to the controller. The controller will compare this incoming signal with the set value.
The pump helps to draw out the air of the inner chamber of the oven. By rotating the knob of the pressure regulator, one can control the flow of air through the chamber.
Process of Vacuum Drying
Follow the following steps to carry on the vacuum drying.
- Turn on the machine.
- Then, set the vacuum pressure and temperature necessary for drying the object.
- Wait until the vacuum dryer reaches to the set value.
- Once the vacuum oven reaches to the set value, place the object to be dried inside the chamber. Wait until the set time has been achieved.
- Finally, remove the object from the machine.
Vacuum dryer is applicable for drying out the heat sensitive materials. So, it is useful in the following sectors.
- Food Industry
- Plastic and the chemical processing
Supplier of Vacuum Oven in Nepal
There are limited trading companies that supply vacuum oven in Nepal. Among them, Eden Technology is one. It is an authorized dealer of vacuum oven of Osworld company. The company is located in Tinkune, Kathmandu. You may contact the given number (+977-1-4780399, 4782481) or send email (firstname.lastname@example.org).
The price of the machine depends upon a number of factors such as quality, size and brand of the product. Also, the price of the product keeps on changing. Hence, I suggest you to contact the supplier to know the price.