Despatch Stackable LCC/LCD - Manual (Page 19)

Stackable LCC/LCD Oven Owner’s Manual T HEORY OF O PERATION
Version 26 19
Copyright © 2010 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
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3.3.3.3. Validation Testing
Despatch recommends the following test sequence for pharmaceutical Class 100 ovens.
1. Proper installation of the HEPA filters (Section 3.3.2).
2. Ambient air challenge to determine integrity of oven chamber and filter
gaskets.
3. Proper filter burn-off procedure.
4. Class 100 testing inside the work chamber.
3.3.3.4. HEPA Filter Burn-off Process Not Necessary
HEPA filters contain a binder material which protects the filter media during production
and shipping. Smoke produced from burning this binder at elevated temperatures is
undesirable during normal oven operation. Burning off the binder will ensure a clean
process at elevated temperatures.
However, when the binder is burned out of the filter media, the filter becomes
very fragile: too fragile to withstand normal shipping and handling. For this reason,
Despatch does not perform the burn-off procedure. The burn-off process is not necessary
at temperatures under 200°C.
3.3.4. HEPA Filter Unit Replacement
Periodic replacement the HEPA filter unit due to:
Resistance, or pressure drop, across the filter unit. Maximum level of resistance in
inches (water gauge) will vary depending upon the operation of the filter and the
available fan capacity. Adequate fan capacity must be available.
Loss of efficiency (leakage), determined from air-sampling measurements made
downstream of the filter unit.
Visible damage or rupture of the filter media in a unit.
Change in process application.
Excessive build-up of lint or combustible particulate matter on the filter unit.
Water droplets in airstream through filter, free water (RH = 100%), will saturate filter
very quickly and may cause burnout or holes in burned off filter media.
High level of radiation in the vicinity of the filter unit.