Despatch RFD Series - Manual (Page 22)

T HEORY OF O PERATION RFD Oven Series Owner’s Manual
22 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.
3.5. Optional High Limit Audible Alarm
High Limit audible and visual alarm is a red light (Figure 13) and small alarm horn located on the
front of the control panel. The alarm is sounded if a High Limit condition occurs. A switch is
provided to silence the alarm. This alarm has a range of 80dB at 2 ft (0.6 m).
3.6. Purge Timer
The Purge timer (Figure 10) prevents the heater from
energizing until flammable solvents within the oven
have been reduced to a safe level by the forced exhaust
system. The red light of the Purge timer illuminates
during the purge cycle.
The Purge timer is pre-set at the factory for the
appropriate purge time. Table 2 and the specification
label (Figure 14) list the appropriate settings. Verify
the setpoint before each use. If the purge time is not
set to the value shown in Table 2 or on the
specification label, adjust as necessary.
Table 2. Purge timer settings for various RFD models.
RFD Model Purge Timer Setting
RFD2-13 4 minutes
RFD2-19 5 minutes
RFD2-35 2.5 minutes
3.7. Airflow Interlocking Safety Switch
The Airflow Interlocking Safety Switch interrupts power to the heater if the forced exhaust
system is not functioning properly (Figure 11).
If the Airflow Interlocking Safety Switch is set too low,
it will not interrupt power to the heater (if the forced
exhaust system were not functioning properly). If the
Airflow Interlocking Safety Switch is set too high, the
heater will not energize, even if the forced exhaust
system is functioning properly. The Airflow Interlocking
Safety Switch setpoint is pre-set at the factory but must
be verified before each use (see Section 6.5 for
adjustment information).
Figure 10. The Purge timer red light is
illuminated during the timing period.
Figure 11. Airflow interlocking safety switch.