ASHRAE Journal - May 2022 - 60

COLUMN DATA CENTERS
* For data center environments, tested with silver and
copper coupons, shown to have corrosion levels less than
300 Å/month for copper and 200 Å/month for silver, suggesting
that only the pervasive pollutants (SO2, NO2, and O3) may be
present, the recommended moisture limit is raised from
60% to 70% RH. The upper moisture limit will now be
70% RH or 59°F (15°C) dew point, whichever is the minimum
moisture content. These changes are reflected in
the environmental envelopes for Low Levels of Gaseous
Pollutants.
* For data center environments, tested with silver and
copper coupons, shown to have levels of corrosion greater
than 300 Å/month for copper or 200 Å/month for silver, suggesting
that Cl2 and/or H2S (or other corrosive catalysts) may be
present, then the recommended moisture levels should
be kept below 50% RH. The upper moisture limit is 50%
RH or 59°F (15°C) dew point, whichever is the minimum
moisture content. Chemical filtration should be considered.
These changes are reflected in the environmental
envelopes for High Levels of Gaseous Pollutants.
In addition, a new high-density environmental class
was added to the Fifth Edition: H1. Both the recommended
(Table 2) and the allowable (Table 3) temperature ranges
for Class H1 are more restrictive than for Class A1. For
Class H1, the recommended temperature range is 64.4°F
to 71.6°F (18°C to 22°C), and the allowable range is 41°F
to 77°F (5°C to 25°C). The recommended humidity range
for Class H1 is the same as for Classes A1 to A4, as shown
in Table 2.
Closing Comments
ASHRAE's Thermal Guidelines for Data Processing
Environments has been a dynamic document serving the
data center community (facility designers, operators
and IT manufacturers) for the past 18 years. The recommended
and allowable operating environments have
been adjusted several times in response to the needs of
society at large for increased energy efficiency, the needs
of the IT manufacturers to produce equipment meeting
the necessities of the IT community and research carried
out by ASHRAE.
This is the first of several columns on the Thermal
Guidelines for Data Processing Environments publications.
The next column will focus on the most recent changes
to the guideline, the Fifth Edition, published in 2021.
Reference to the full guideline (Thermal Guidelines for Data
Processing Environments (Fifth Edition), available from the
ASHRAE Bookstore) is recommended to provide significantly
more instruction, guidance and context.
References
1. ASHRAE. 2004. Thermal Guidelines for Data Processing Environments
(First Edition). Atlanta: ASHRAE.
2. Schmidt, R.R., C. Belady, A. Classen, T. Davidson, et al. 2004.
" Evolution of data center environmental guidelines. " ASHRAE
Transactions 110(1).
3. ASHRAE. 2021. Thermal Guidelines for Data Processing Environments
(Fifth Edition). Peachtree Corners: ASHRAE.
4. ASHRAE. 2008. Thermal Guidelines for Data Processing Environments
(Second Edition). Atlanta: ASHRAE.
5. ASHRAE. 2012. Thermal Guidelines for Data Processing Environments
(Third Edition). Atlanta: ASHRAE.
6. ASHRAE. 2015. Thermal Guidelines for Data Processing Environments
(Fourth Edition). Atlanta: ASHRAE.
7. Wan, F., D. Swenson, M. Hillstrom, D. Pommerenke, C. Stayer.
2014. " The effect of humidity on static electricity induced reliability
issues of ICT equipment in data center-motivation and setup of the
study. " ASHRAE Transactions 119(2).
8. Zhang, J., R. Zhang, R. Schmidt, J. Gilbert, B. Guo. 2019.
" Impact of Gaseous Contamination and High Humidity on the
Reliable Operation of Information Technology Equipment in Data
Centers. " ASHRAE Research Project RP-1755, Final Report.
60
ASHRAE JOURNAL ashrae.o rg M AY 2 0 2 2
http://www.shortridge.com http://ashrae.org
ASHRAE Journal - May 2022

Table of Contents for the Digital Edition of ASHRAE Journal - May 2022
