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Friction-aire

U.L. listed for Class I Group D operation ... the first and only oven to have this listing

Friction-Aire chambers can be used for a number of hazardous work applications due to the unique operating concept of providing controlled heat without heating elements. This characteristic helps solve the problem of operational safety when operating in a Class 1, Group D processing environment by removing an ignition source.

Three models of the Friction-Aire family are listed by Underwriter's Laboratories. These chambers are the first and only electric ovens to have ever been so listed.

Friction-Aire ovens are a sound solution to the Class 1, Group D processing applications. If you would like more information or need help in choosing the right chamber for your specific application requirement, please let us know. We would like to be of service.

How it works

The Friction-Aire oven provides a controlled environment with 100% straight-line proportional temperature performance without heating elements or electrical controls. It uses a unique high velocity air-flow system

Over-temperature protection
Non-electrical system powered by its own secondary bellows responds to its own sensing element. A spring-loaded vent with inlet area greater than control vent area is latch-closed by reset lever on control panel. If main control fails, properly set OTP safety trips vent latching mechanism to lock vent in the fully open position. Resulting increase in exhaust capacity immediately drops chamber temperature. Vent must be re-closed by manually pressing the reset lever. Oven operation continues at safe temperature.

Control operation
A temperature-sensitive bellows regulates fresh ambient air to a blower system. Temperature is set by control dial. As the temperature rises with blower operation, bellows expand to open and position the control grate. More air enters the system causing sharp temperature curve-off and stabilization.

Adjustable by-pass damper vane establishes control inlet pressure. When horizontal, the damper restricts path of blower only through control. Since this reduces CFM and velocity, heating is minimized for control at lower temperatures. When damper is vertical, system recalculates at maximum for maximum heat.

While a large air volume must be moved to generate heat, much of it passes through the by-pass chamber surrounding the work chamber. The small percentage passing through the inner chamber is practical for most applications, to move air through a prescribed pattern to generate heat. This concept offers a number of advantages.

Solid side walls are available for applications involving the drying of lightweight powders and other sensitive airborne product loads.

Temperature uniformity
There is no central heat source in the system. Heat is generated within the air as it moves using a blower to develop turbulence and friction. As a result there are no hot spots, and no points within the chamber that exceed the indicated air temperature. Temperature stratification problems are therefore eliminated by Friction-Aire.

Natural interlock of blower and heat
This characteristic means that if the motor/ blower system fails - the only source of heat - the chamber temperature will automatically drop. No dangerous temperature runaway conditions exist in this system.

If air circulation stops, there are no uncontrolled heating elements to increase oven temperature above the set point of the control.

The need for a timed purge cycle is eliminated to avoid igniting the air/solvent mixture at start-up. When product is initially placed in the oven, a high concentration of volatiles is present due to rapid evaporation from the product. When a conventional heating element design is used, this concentration must be diluted by a timed purge cycle prior to air heater turn-on. Since there is no ignition source, Friction-Aire eliminates the need

Built-in over-temperature protection
The Friction-Aire incorporates a unique and intrinsically safe non-electrical over-temperature protection system. It is powered by its own secondary bellows. The bellows responds to its own sensing bulb. A spring loaded vent with an inlet area greater than the control vent area is latch-closed by a reset lever on the control panel.

If the main control fails, the OTP safety sending bellows trips the vent latching mechanism to lock the vent in the fully open position. The resulting increase in exhaust capacity immediately drops the chamber temperature. The vent must be re-closed manually by pressing the reset lever. Oven is then ready to continue operation.

Fast cool-down rates
High-velocity air generated by the blower system is fully controllable within the work chamber and reduced to a practical rate during the work cycle.

Fast cool-down is an inherent capability of the system. Typically, an empty oven temperature will drop from +150 C to +50 C in thirty minutes.

Greater cost-effective performance
Energy savings over conventional ovens are substantial. There is less to maintain and service with Friction-Aire, due to the type of construction and basic operational concept.

Friction-aire accessories