Table 2. Limits for particulates and gases
Contaminant Limits
Gaseous Severity level G1 as per ANSI/ISA 71.04-1985
1
, which states that the reactivity rate of copper
coupons shall be less than 300 Angstroms per month (Å/month, ≈ 0.0039 μg/cm
2
-hour weight
gain).
2
In addition, the reactivity rate of silver coupons shall be less than 200Å/month (≈ 0.0035
μg/cm
2
-hour weight gain).
3
The reactive monitoring of gaseous corrosivity must be conducted
approximately 5 cm (2 in.) in front of the rack on the air inlet side at one-quarter and three-quarter
frame height off the floor or where the air velocity is much higher.
Particulate Data centers must meet the cleanliness level of ISO 14644-1 class 8. For data centers without
airside economizer, the ISO 14644-1 class 8 cleanliness might be met by choosing one of the
following filtration methods:
• The room air might be continuously filtered with MERV 8 filters.
• Air entering a data center might be filtered with MERV 11 or preferably MERV 13 filters.
For data centers with airside economizers, the choice of filters to achieve ISO class 8 cleanliness
depends on the specific conditions present at that data center.
The deliquescent relative humidity of the particulate contamination should be more than 60%
RH.
4
Data centers must be free of zinc whiskers.
5
1
ANSI/ISA-71.04-1985. Environmental conditions for process measurement and control systems: Airborne
contaminants. Instrument Society of America, Research Triangle Park, North Carolina, U.S.A.
2
The derivation of the equivalence between the rate of copper corrosion growth in the thickness of the corrosion
product in Å/month and the rate of weight gain assumes that Cu2S and Cu2O grow in equal proportions.
3
The derivation of the equivalence between the rate of silver corrosion growth in the thickness of the corrosion
product in Å/month and the rate of weight gain assumes that Ag2S is the only corrosion product.
4
The deliquescent relative humidity of particulate contamination is the relative humidity at which the dust absorbs
enough water to become wet and promote ionic conduction.
5
Surface debris is randomly collected from 10 areas of the data center on a 1.5 cm diameter disk of sticky
electrically conductive tape on a metal stub. If examination of the sticky tape in a scanning electron microscope
reveals no zinc whiskers, the data center is considered free of zinc whiskers.
Management offerings
The XClarity portfolio and other system management offerings described in this section are available to help
you manage the servers more conveniently and efficiently.
Chapter 1. Introduction 11
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