Instruction Manual

THEORY OF OPERATION LAC Series Oven Owner’s Manual

20 Version 1

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3.2.1.3. Other Damper Settings

The damper can be set to several other distinct operating positions. In most cases the damper

setting is influenced by two specific performance factors: uniformity and cool-down rates.

Chamber Uniformity

The system’s inside chamber pressure influences chamber uniformity. Pressure inside the

chamber depends on the amount of fresh air flowing into the chamber. When a large volume of

fresh air flows into the chamber, the chamber pressurizes slightly and overall temperature

uniformity improves. The slightly pressurized chamber produces the effect of "pushing" air to the

corners of the chamber. Typically the corners of the chamber improve with respect to temperature

distribution while the core of the chamber maintains excellent uniformity characteristics

regardless of damper position.

Pressurization of the chamber typically is a factor when the chamber is loaded heavily. The best

uniformity results, with respect to the product, are achieved when no more than two-thirds of any

inside chamber dimension are used. The best overall results are achieved when the product(s) are

located in the center of the chamber.

Cool-Down Rates

The more open the damper, the faster the cool-down.

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Over-pressuring the chamber can cause hot air to blow out

around the door seal and cause the area around the door to

be hot to the touch. Eliminate this hot air from entering the

room by closing the damper slightly until the air stops

blowing.

3.3. The Protocol 3 Controller

The Protocol 3 is a microprocessor based digital temperature controller designed for simple and

flexible oven operation (Figure 5). The Protocol 3 controller operates as a dual-functioning

controller/High Limit instrument. The control portion utilizes a time proportioning voltage signal

to control heating devices with minimal temperature fluctuations.

The High Limit portion protects the product and/or the oven from overheating. If the product

being processed has a critical high temperature limit, the High Limit setpoint should be set to a

temperature somewhat below the temperature at which the product could be damaged. If the

product does not have a critical high temperature limit, the High Limit setpoint should be set 5 to

15 degrees higher than the maximum programmed setpoint at which the oven will operate.

The Protocol 3 controller provides three primary operating modes:

 Manual: Oven operates continuously at a fixed temperature until turned off.