A routine preoperational inspection revealed some unexpected conditions in a computer. Upon closer inspection two types of contamination were discovered in addition to pitting in the undersurface of an underfloor air plenum cover. One of the contaminants was a white powder; the other was an accumulation of brown/black particles. A heavy deposit of white material, similar to that found in the chassis, was found among the pumps supplying water to humidify the cooling air in the unit.

The contamination had not caused any electrical problems when discovered; however, it did cause concern for the long-term integrity of the unit. The contaminants were analyzed to determine their origin. The white powder in the computer was the same as that found around the pumps; it was deposited by changes in the air velocity due to the design of the chassis. The brown/black residue from the plenum was found to be rust. The rust and cover pitting were directly attributable to corrosion caused by highly ionized water used for humidifying the unit. A water purification system was added to remove the corrosive ions to prevent subsequent corrosion after the computer chassis was cleaned. Design approaches to preventing such problems are also discussed.

Subject
Water, Materials, Piping, Composition, Plating, Contamination, Residues, Calcium, Inspection, Sodium, Powders, Deposit corrosion, Elements
© 1986 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1986
Association for Materials Protection and Performance (AMPP)
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