ASHRAE Journal - March 2015 - 73
COLUMN DATA CENTERS
classify shoes as ESD dissipative or non-ESD dissipative,
and the floor as ESD dissipative or non-ESD dissipative.
This study went into far more detail. For instance, 11
different shoe types were investigated and a total of 13
types of floors were also investigated (see Table 1 for the
full list).
Finally, a total of four relative humidity levels were
examined: 60%, 35%, 15%, and (as an added requirement) 8%. While 8% RH may seem excessively low, as
mentioned earlier, two new environmental classes
of IT equipment (A3 and A4) were added as Thermal
Guidelines environmental classes in the middle of this
research project, and TC 9.9 was able to obtain ASHRAE
approval for the scope of the research to be extended
from 15% RH down to 8% RH.
FIGURE 1 2004 and 2008 recommended ranges.
80 90% 80%
70%
75
70
50%
65
We
t-
40%
60
55
50
80%
ESD in Real Life vs. Research Simulation
30%
2004
2008
20%
60%
MARCH 2015
ashrae.org
ASHRAE JOURNAL
73
SOURCE: ASHRAE. MODIFIED BY DLB
We
t-
Bu
lb
Tem
pe
rat
Dew-Point Temperature °F
ure
°F
10%
In real life, ESD can cause:
40%
* Self-correcting errors (such as a lost package in LAN
20%
traffic);
45 50
55
60
65
70
75 80
85
* An upset that may need user intervention; or
Dry-Bulb Temperature °F
* Actual physical damage to IT equipment.
For research purposes,
FIGURE 2 2004 and 2008 allowable ranges.
measurements of these
failure modes were not speRelative Humidity
cifically documented, as the
90% 80% 70% 60% 50%
40%
30%
80
80
robustness of specific models of equipment varies so
75
75
widely. Rather, voltages and
durations were measured,
70
70
and these were compared
20%
65
to the industry standard
65
ASHRAE 2004/2008 -
voltages (4kV and 8kV)
Class 2 Allowable
60
60
defined in the International
ASHRAE 2004/2008 -
55
Class 1 Allowable
Electrotechnical
55
50
Commission document IEC
10% 50
45
Recommended
61000-4-2.
45
40
40
35
Rather than absolute values,
35
30
the report generally provides
20
data in terms of relative prob10
0
abilities of harmful events.
35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120
This strategy is similar to the
Dry-Bulb Temperature °F
x-factor that is defined in
Thermal Guidelines.
The value of the x-factor is a ratio, defined as the
under environmental condition B." If one has empirical
"Number of equipment failures under environmental
data on the ESD failure rate at one relative humidity, the
condition A divided by Number of equipment failures
results of the study allow one to estimate the change in
SOURCE: ASHRAE. MODIFIED BY DLB
Bu
lb T
em
per
atu
re
°F
60%
55%
ASHRAE Journal - March 2015
Table of Contents for the Digital Edition of ASHRAE Journal - March 2015
Contents
ASHRAE Journal - March 2015 - Intro
ASHRAE Journal - March 2015 - Cover1
ASHRAE Journal - March 2015 - Cover2
ASHRAE Journal - March 2015 - 1
ASHRAE Journal - March 2015 - 2
ASHRAE Journal - March 2015 - Contents
ASHRAE Journal - March 2015 - 4
ASHRAE Journal - March 2015 - 5
ASHRAE Journal - March 2015 - 6
ASHRAE Journal - March 2015 - 7
ASHRAE Journal - March 2015 - 8
ASHRAE Journal - March 2015 - 9
ASHRAE Journal - March 2015 - 10
ASHRAE Journal - March 2015 - 11
ASHRAE Journal - March 2015 - 12
ASHRAE Journal - March 2015 - 13
ASHRAE Journal - March 2015 - 14
ASHRAE Journal - March 2015 - 15
ASHRAE Journal - March 2015 - 16
ASHRAE Journal - March 2015 - 17
ASHRAE Journal - March 2015 - 18
ASHRAE Journal - March 2015 - 19
ASHRAE Journal - March 2015 - 20
ASHRAE Journal - March 2015 - 21
ASHRAE Journal - March 2015 - 22
ASHRAE Journal - March 2015 - 23
ASHRAE Journal - March 2015 - 24
ASHRAE Journal - March 2015 - 25
ASHRAE Journal - March 2015 - 26
ASHRAE Journal - March 2015 - 27
ASHRAE Journal - March 2015 - 28
ASHRAE Journal - March 2015 - 29
ASHRAE Journal - March 2015 - 30
ASHRAE Journal - March 2015 - 31
ASHRAE Journal - March 2015 - 32
ASHRAE Journal - March 2015 - 33
ASHRAE Journal - March 2015 - 34
ASHRAE Journal - March 2015 - 35
ASHRAE Journal - March 2015 - 36
ASHRAE Journal - March 2015 - 37
ASHRAE Journal - March 2015 - 38
ASHRAE Journal - March 2015 - 39
ASHRAE Journal - March 2015 - 40
ASHRAE Journal - March 2015 - 41
ASHRAE Journal - March 2015 - 42
ASHRAE Journal - March 2015 - 43
ASHRAE Journal - March 2015 - 44
ASHRAE Journal - March 2015 - 45
ASHRAE Journal - March 2015 - 46
ASHRAE Journal - March 2015 - 47
ASHRAE Journal - March 2015 - 48
ASHRAE Journal - March 2015 - 49
ASHRAE Journal - March 2015 - 50
ASHRAE Journal - March 2015 - 51
ASHRAE Journal - March 2015 - 52
ASHRAE Journal - March 2015 - 53
ASHRAE Journal - March 2015 - 54
ASHRAE Journal - March 2015 - 55
ASHRAE Journal - March 2015 - 56
ASHRAE Journal - March 2015 - 57
ASHRAE Journal - March 2015 - 58
ASHRAE Journal - March 2015 - 59
ASHRAE Journal - March 2015 - 60
ASHRAE Journal - March 2015 - 61
ASHRAE Journal - March 2015 - 62
ASHRAE Journal - March 2015 - 63
ASHRAE Journal - March 2015 - 64
ASHRAE Journal - March 2015 - 65
ASHRAE Journal - March 2015 - 66
ASHRAE Journal - March 2015 - 67
ASHRAE Journal - March 2015 - 68
ASHRAE Journal - March 2015 - 69
ASHRAE Journal - March 2015 - 70
ASHRAE Journal - March 2015 - 71
ASHRAE Journal - March 2015 - 72
ASHRAE Journal - March 2015 - 73
ASHRAE Journal - March 2015 - 74
ASHRAE Journal - March 2015 - 75
ASHRAE Journal - March 2015 - 76
ASHRAE Journal - March 2015 - 77
ASHRAE Journal - March 2015 - 78
ASHRAE Journal - March 2015 - 79
ASHRAE Journal - March 2015 - 80
ASHRAE Journal - March 2015 - 81
ASHRAE Journal - March 2015 - 82
ASHRAE Journal - March 2015 - 83
ASHRAE Journal - March 2015 - 84
ASHRAE Journal - March 2015 - 85
ASHRAE Journal - March 2015 - 86
ASHRAE Journal - March 2015 - 87
ASHRAE Journal - March 2015 - 88
ASHRAE Journal - March 2015 - 89
ASHRAE Journal - March 2015 - 90
ASHRAE Journal - March 2015 - 91
ASHRAE Journal - March 2015 - 92
ASHRAE Journal - March 2015 - 93
ASHRAE Journal - March 2015 - 94
ASHRAE Journal - March 2015 - 95
ASHRAE Journal - March 2015 - 96
ASHRAE Journal - March 2015 - Cover3
ASHRAE Journal - March 2015 - Cover4
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