Despatch RAD Series - Manual (Page 16)

T HEORY OF O PERATION RAD Oven Series Owner ’s Manual
16 Version 1
Copyright © 2012 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.
Table 1. Damper Positions for Chamber Pressure.
3.2.1. Determining Damper Settings
The optimum setting for the amount of fresh air that should be distributed into the chamber
depends on several factors. These factors include ambient environment temperature, load
conditions, load distribution, heat-up rates, cool-down rates, desired temperature uniformity and,
most importantly, the desired operating temperature. Carefully consider existing engineering
tradeoffs while using guidelines to determine the fresh air damper setting.
In general, the damper should be set so that the amount of fresh air flowing into the chamber
agrees with the desired operating temperature conditions. The following paragraphs show the
considerations involved with various damper position settings.
3.2.1.1. Fresh Air Damper Fully Closed Position
The chamber achieves maximum attainable heat-up rates when the fresh air damper lies in the full
closed position. With the damper in the full closed position, the chamber will operate at the
desired temperature using the minimum amount of power. In most cases, the oven also efficiently
operates at the chamber’s maximum operating temperature when in the full closed position.
3.2.1.2. Fresh Air Damper Fully Open Position
The chamber operates at its minimum operating temperature with the fresh air damper in full
open position.
Friction heat from the air recirculation system builds up in the chamber. This causes chamber
temperature to rise slightly even without the heating system on. The chamber reaches thermal
equilibrium temperature after the recirculation motor runs for an extended period of time.
Damper Position
Fresh Air Open Closed
Exhaust Closed Open
Chamber Pressure Positive Negative
Warning!
Maintain slight positive pressure to regulate heat.
Too much positive pressure in an oven can create a high outer
skin temperature as hot air is forced out through panel joints
and around door seal. High outer skin temperature could warp
the front of the oven.