©2021 ITW EAE. All rights reserved. Despatch is a registered trademark in the U.S. and other
countries. No part of the contents of this manual may be reproduced, copied or transmitted in any form
or by any means without the written permission from ITW EAE - Despatch, unless for purchaser's
personal use.
6.4. Operating Procedure
6.4.1. HEPA Filter Burn-off and Validation Testing
Despatch Industries guarantees the HEPA filters will meet specified efficiency
ratings when the following recommendations are followed:
• The filter is properly installed
• The filter is run at or below 180°C, at a constant temperature
• The filter is burned off at 260°C for 48 hours before running
6.4.1.1. D.O.P. Testing
D.O.P. testing uses aerosol particles of submicron size to spot defects or measure
filter efficiency. Degenerative by-products of this test are distributed throughout
the oven chamber upon heat-up. These and other organic challenge agents
present a fire hazard for LCC/LCD Non-Class A (NFPA 86) ovens. Despatch does
not recommend D.O.P. filter testing.
6.4.1.2. Class 100 Testing
Despatch guarantees a Class 100 environment within the oven. This classification
is based on measurement of the particulate level within the oven work chamber.
Class 100 testing may be performed before or after a proper filter burn-off
procedure has been performed. Despatch guarantees Class 100 condition
measurements based on two methods of test. The direct method employs an
extraction-type particulate analyzer. The indirect method involves particle settling
over a specified period of time onto a clean disk. Please consult factory for
expected levels.
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