Mechanical Convection Vacuum Ovens

Essentially, the MCV option combines the functionality of a mechanical convection oven and a vacuum oven into one unit. The option is available on any ST (standard) or STX (explosion-proof) vacuum oven.

How it Works:
The option involves the addition of a radial blower assembly into the vacuum vessel to circulate the atmosphere inside the oven. When the oven is operating at a full or partial atmospheric pressure, the blower is switched on via a programmed event. The typical configuration is locating the blower in the center of the back wall of the vacuum vessel. During operation, air is drawn into the blower from the center of the workspace and it is distributed into the workspace in a forward direction from the back wall – along the left and right sides. This provides a horizontal airflow direction through the workspace. Other configurations have been designed to provide the best airflow for the particular process. These include vertical airflow with the blower installed in the bottom of the workspace and horizontal airflow with (2) blower assemblies installed in the top of the workspace for a pass-through configuration. The blower wheel is shaft-driven and it rotates through a ferrofluidic mechanical seal. The blower shaft is belt driven and the motor is mounted externally. The blower wheel is dynamically balanced and the entire assembly is quiet and vibration-free. The units are designed to provide a minimum of 150 feet per minute air velocity through the workspace. This is a nominal value for a well-performing mechanical convection oven. During operation at a low pressure, the blower is switched off and the oven operates as a normal vacuum oven.

Advantages:
Two ovens in one. Many customers process their products in a convection oven first and then transfer the product to a vacuum oven to complete the process. The MCV option eliminates this step thereby improving productivity.

Excellent temperature uniformity. The MCV option allows the product to be heated very uniformly in an atmosphere of nitrogen or air prior to the vacuum stage of the process. Typically +/- 1 °C uniformity is observed throughout the entire load after the product has been brought up to temperature and stabilized. Once heated in an atmosphere, the vacuum stage of the process proceeds and the product maintains its uniform temperature.

More rapid heat-up and cool-down. A 1°C / minute heat-up rate ensures acceptable uniformity during transition to processing temperature. The MCV option provides this capability and it is much superior to a conventional vacuum oven. The additional vessel cooling option combined with the MCV option will cool the product much more rapidly than if the product were in a vacuum oven alone.

 

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