T
HEORY OF
O
PERATION
LAC Series Oven
Owner’s Manual
18
Version 106
Copyright © 2011 by Despatch Industries.
All rights reserved. No part of the contents of this manual may be reproduced, copied or transmitted in any form or by any
means including graphic, electronic, or mechanical methods or photocopying, recording, or information storage and
retrieval systems without the written permission of Despatch Industries, unless for purchaser's personal use.
the recirculation motor has been ON for an extended period of time, the chamber reaches
a thermal equilibrium temperature.
When the damper is not set to full-open position, the chamber has no way to readily
dissipate the heat generated by the friction. With the damper fully open, the thermal
equilibrium temperature is the minimum operating temperature of the chamber.
When the damper is in the full-open position, the oven may not
be able to heat to the maximum oven operating temperature.
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.
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.
