Air Supply And Flow; Air Cleanliness - HP 3PAR StoreServ 7450c Planning Manual

relative humidity for a subsystem equipment room should be set at 40%. This level is sufficient to
suppress electromagnetic charge buildup, and low enough to avoid the risk of corrosion and
condensation. To avoid air contamination from the humidifier, water treatment may be necessary
in areas with high mineral content.

Air Supply and Flow

The air flow capacity of the facility where the storage systems are installed needs to be sufficient
to remove the heat generated by the equipment. In addition, the air handlers must provide the
airflow volume required by the units being cooled. To ensure this airflow, the facility must have a
positive air pressure underneath the floor (if the facility has raised floors). When conditions within
the computer room are changed (new units are added, the computer system is moved, and so on),
airflow checks should be made.
The amount of outside (composition) air should be kept to the minimum needed to create a slight
positive pressure within the room, and it should not exceed industry recommendations of 0.3 cubic
meters/minute (10 cubic feet/minute) per person stationed in the equipment room. While
recommendations for outside air in comfort air conditioning are 10–15% of the airflow, the computer
room environment is cleaner and operates more efficiently if outside air is kept below 1 percent
of the airflow. Cooling/heating and humidification needs are reduced, and a minimum of
contaminated building air is introduced into the installation area.

Air Cleanliness

Air contaminants can cause equipment malfunction and can damage storage systems. It is essential
that steps be taken to prevent air contaminants, such as metal particles, solvent vapors, corrosive
gases, soot, airborne fibers, or salt, from entering or being generated within the server room
environment.
A high-efficiency air filter should be employed on each air inlet for outside air to stop dust at the
point of entry to the installation site. Special additional filtering is necessary where the environment
is exposed to salt air, corrosive gases, or unusual dust/dirt conditions. Electronic equipment is
sensitive to air contaminants such as the following:
Excessive amounts of soot particles
Condensate particulates such as carbonates
Concrete particulates from unsealed concrete
Metal flakes or filings, such as those produced by sawing, filing, or drilling
Floor-cleaning solutions with high ammonia content.
Deteriorating/decomposing building materials, including floor tiles, fabrics, sheetrock,
insulation, and acoustical tiles
Pollutants generated by any servicing performed in and around the computer room
Paper chaff, dust, and toners from printers within the computer room
Processing chemicals from reproduction equipment such as microfiche processors.
In electronic equipment, contaminants cause connector contact and motor-bearing degradation.
They also cause electrical leakage, shorting paths between integrated circuit leads and between
printed wiring traces on printed circuit boards.
Air supplied to and circulated within the server room and plenums underneath the floor should
ideally pass through mechanical or electrostatic filters. HVAC ducts and plenums and sub-floor
areas, including cable raceway openings (where used), should be kept clean. All unused cables,
hardware, and debris should be removed from the area underneath the floor to avoid becoming
dust/dirt traps or potential sources of rust.
During major changes in the server room environment, special considerations must be taken into
account whenever any drilling, sawing, welding, brazing, and so on, is performed.
20 Structural/Environmental Considerations