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Technical support:
HVAC applications in the data processing centres
HVAC applications in data processing centres are
often a challenge. They are full of terms such as
reliability, redundancy, availability, tiering require-
ments, and so on. They are full of uncertainty. Some
attempt to resolve technical safety issues with fail-
safe fieldbus. In the end you are left wondering
why the facility was not accepted. Therein lies a
simple but important rule.
Classification of data processing centres
There are 4 categories of data processing centre (tier
I to tier IV). Tier I is the lowest level and means noth-
ing more than a «normal» server room in any build-
ing, while tier IV data centers must meet the high-
est requirements for maintenance and availability.
The criteria for classification can be found in «Data
Center Site Infrastructure Tier Standard: Operational
Sustainability» from the Uptime Institute. This Santa
Fe institute, established in 1993, has a leading role in
improving «uptime» in data processing centres.
Saia
®
PCD
in data centre applications
Technically, you can solve everything in a data centre with Saia®PCD.
The big hurdle is uncertainty, as the necessary knowledge is often lacking.
With this article, we hope the fog lifts a little.
Author: Kostas Kafandaris
The criteria for classification are complex, and cover
not only requirements in terms of equipment, but also
those relating to the building and its personnel. For
example, tier III data processing centres must have a
maintenance technician present in the data process-
ing room 24/7. Tier II classification requires normal
(
manufacturer) support or on-call support five days a
week during a shift. And a tier I center, coffee cups and
microwaves are allowed for use by staff.
Impact on the HVAC application
Tier classification specifies the availability of a data
centre.
However, it does not indicate how the HVAC appli-
cation must be designed and implemented. What is
clear is that availabilities of between 99.671% (tier I)
and 99.991% (tier 4) increase the demands on HVAC
infrastructure. That’s why it’s important that automa-
tion stations not only comply with the PLC hardware
standard IEC61131-2, but also with extra require-
ments such as those for shipbuilding certification.
This provides a sound basis for meeting the criteria,
particularly for tiers III and IV.
Source:
Extract from PDF: «Data
Center Site Infrastructure
Tier-Standard: Operational
Sustainability»
Classification according to the tiering concept
Tier I
Tier II
Tier III
Tier IV
Redundancy
N
N+1
N+1
2
x (N+1)
Supply paths
1
1
1
x active
1
x passive
2
Maintenance
during operation
no
no
yes
yes
Single point of
failure
Multiple failures Multiple failures Multiple failures
none + fire
fault tolerance
none
none
yes
yes
Several fire com-
partments
not required
not required
required
required
Thermal control
220–320
W/m
2
430–540
W/m
2
1070–1620
W/m
2
>1620W/m
2
Period under
consideration
1
year
2
years
5
years
5
years
Limited operation
(
maintenance)
2
downtimes
in 12 hours
3
downtimes in 12
hours
0
0
Downtime
1.2
failures
over 4 hours
2
failures
over 4 hours
2
failures
over 4 hours
1
failure
over 4 hours
Annual IT
down- time
28.8
h
22.0
h
1.6
h
0.6
h
Availability
99.671%
99.749%
99.982%
99.991%
This table isanexcept from the tieringclassificationand isnotcomplete.Table taken from theUptime Institute
Classification according to the tiering concept
Source:
Ausfallzeit_RZ_V5_0.pdf
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