Air Corrosivity in U.S. Outdoor-Air-Cooled Data Centers is Similar to That in Conventional Data Centers (LBNL-4951E)

Overview

Published in 2011 by Henry Coles, Tae Won Han, Phillip Price, Ashok Gadgil and William Tschudi, this LBNL report (LBNL-4951E) is a field study of the corrosion risk from airborne contaminants in outdoor-air-cooled data centres. It compares economizer facilities that use outside air with closed, recirculating ones. The report is freely readable and sets out to answer with data one of the main reservations about the spread of outdoor-air cooling in the US.

The method rests on corrosion classification coupons. Copper and silver coupons were exposed for 30 days. They were placed in three locations: outside (before filtration), in supply air after the filters, and inside the server rooms. This arrangement makes it possible to see separately the raw quality of the outside air and the effect of filtration and of the facility's own conditions.

The study evaluated 19 data centres in the US and 2 in India. The headline finding is stated in the title: corrosivity in US outdoor-air-cooled data centres is similar to that in conventional closed data centres. In other words, for the US sample it could not be shown that using an economizer by itself markedly raises corrosion risk. The study's limits are also clear: the result is bounded by the facilities examined and the 30-day exposure, and it applies mainly to the US; the two Indian sites sit outside the generalisation in the title. Coupon monitoring is therefore sensible in other climates and pollution conditions. Related documents include ANSI/ISA-71.04 and the ASHRAE TC 9.9 contamination white paper.

Key points

1. 19 data centres in the US and 2 in India were evaluated.
2. Copper and silver corrosion classification coupons were exposed for 30 days.
3. Coupons were placed outside (before filtration), in supply air after filters and inside server rooms.
4. Finding: corrosivity in US outdoor-air-cooled data centres is similar to conventional closed data centres.
5. The study compares economizer and closed-circuit facilities.
6. Report LBNL-4951E, 2011; freely readable.
7. Related documents: ANSI/ISA-71.04 and the ASHRAE TC 9.9 contamination white paper.

Using it in design

• When users select airside economization, show a contamination note and suggest coupon monitoring rather than ruling the option out.
• Link to the ASHRAE contamination guidance already in the library.
• Include coupon placement at outside air, post-filter supply and server room locations in the monitoring plan.
• Do not generalise the result directly to regions outside the sample, such as India; ask for local measurement.

Who should read it

Mechanical designers evaluating economizer cooling and preparing air-quality, corrosion and contamination monitoring plans.

Related standards

• ANSI/ISA-71.04
• ASHRAE TC 9.9 contamination white paper

Publication details

Authors

Henry C. Coles; Tae Won Han; Phillip N. Price; Ashok J. Gadgil; William F. Tschudi

Publisher

Lawrence Berkeley National Laboratory

Year

2011

Document number

LBNL-4951E

Document language

English

Source type

Government / public

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation