IBM DS8700, Introduction And Planning Manual

Page: 190 / 256

is conducted approximately 2 inches (5 cm) 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 contamination
Data centers must meet the cleanliness level of ISO 14644-1 class 8. For
data centers without airside economizers, the ISO 14644-1 class 8
cleanliness can be met by selecting one of the following filtration methods:
v
The room air can be continuously filtered with MERV 8 filters.
v Air entering a data center can 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 must 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, NC, 1985.
2. The derivation of the equivalence between the rate of copper corrosion product
thickness growth in Å/month and the rate of weight gain assumes that Cu
2
S
and Cu
2
O grow in equal proportions.
3.
The derivation of the equivalence between the rate of silver corrosion product
thickness growth in Å/month and the rate of weight gain assumes that Ag
2
S 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
corrosion, ion migration, or both.
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.
Cooling the storage complex
You can take steps to optimize the air circulation and cooling for your storage
units.
To optimize the cooling around your storage units, prepare the location of your
storage units as recommended in the following steps.
Note: The installation of a storage unit is done by IBM service representatives.
However, the following steps describe the process needed to optimize the
air circulation and cooling for your storage units.
DS8700
1. Prepare for the installation of the storage unit on a raised floor.
Although the storage unit can be installed on a nonraised floor,
installing the storage unit on a raised floor provides increased air
circulation for better cooling.
2. Install perforated tiles in the front and back of each base model and
expansion model as follows:
a.
For a stand-alone base model, install two fully perforated tiles in
front of each base model and one partially perforated tile at the
168
Introduction and Planning Guide