HP Rp3440-4 - 9000 - 0 MB RAM User manual

Generic Site Preparation Guide
HP Part Number: 5991-6018
Published: June 2009
Edition: Third Edition

Legal Notices
© Copyright 2009 Hewlett-Packard Development Company, L.P.
The information contained herein is subject to change without notice.
The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services.
Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions
contained herein.
Revision History
First Edition Initial release, August 2005. P/N is A7025-96015.
Second Edition April 2008. P/N changed to 5991–5990.
Third Edition June 2009. P/N changed to 5991–6018.

Table of Contents
1 General Site Preparation Guidelines...........................................................................7
Electrical Factors.....................................................................................................................................7
Synopsis.............................................................................................................................................7
AC Electrical Distribution System...............................................................................................7
AC Power Quality Devices..........................................................................................................7
UPS Recommendations................................................................................................................8
Power Consumption....................................................................................................................8
Grounding Systems......................................................................................................................8
Comprehensive Discussion...............................................................................................................9
Computer Room Safety.....................................................................................................................9
Fire Protection..............................................................................................................................9
Fire Suppression.........................................................................................................................10
Lighting Requirements for Equipment Servicing......................................................................10
Cabinet Recommendations........................................................................................................10
Working Space for Server Access...............................................................................................10
Power Consumption........................................................................................................................10
Electrical Load Requirements (Circuit Breaker Sizing)...................................................................11
Power Quality..................................................................................................................................11
Sources of Voltage Fluctuations.................................................................................................11
Power System Protection............................................................................................................11
Distribution Hardware....................................................................................................................12
Wire Selection.............................................................................................................................12
Raceway Systems (Electrical Conduits) (LAHJ).........................................................................12
Building Distribution.................................................................................................................12
Grounding Systems.........................................................................................................................12
Power Distribution Safety Grounding (LAHJ)..........................................................................12
Main Building Electrical Ground..........................................................................................12
Electrical Conduit Ground....................................................................................................13
Power Panel Ground.............................................................................................................13
Computer Safety Ground.....................................................................................................13
Dual Power Source Grounding.............................................................................................13
Cabinet Performance Grounding (High-Frequency Intercabinet Ground)...............................13
Raised Floor “High-Frequency Noise” Grounding...................................................................13
Equipment Grounding Implementation Details........................................................................14
System Installation Guidelines........................................................................................................15
Wiring Connections....................................................................................................................15
Data Communications Cables....................................................................................................15
Environmental Elements.......................................................................................................................15
Synopsis...........................................................................................................................................15
Air Quality.................................................................................................................................15
Airflow.......................................................................................................................................16
Equipment Orientation..............................................................................................................16
Electrostatic Discharge (ESD): Source of Greatest Failure Rate Without Detection..................17
Cellular Telephone and Wireless Usage.....................................................................................17
Comprehensive Discussion.............................................................................................................17
Computer Room Preparation..........................................................................................................17
Airflow.............................................................................................................................................18
Row Orientation.........................................................................................................................18
Dust and Pollution Control........................................................................................................18
Metallic Particulate Contamination...........................................................................................19
Cooling Requirements.....................................................................................................................20
Table of Contents 3

Basic Air-Conditioning Equipment Requirements....................................................................20
Air-Conditioning System Guidelines.........................................................................................20
Air-Conditioning System Types.................................................................................................20
Basic Air-Distribution Systems..................................................................................................21
Air-Conditioning System Installation........................................................................................21
Air-Conditioning Ducts.............................................................................................................21
Humidity Level................................................................................................................................22
ESD Prevention................................................................................................................................22
Humidity Levels Influence the Creation of Static Charges.............................................................22
Relative Humidity...........................................................................................................................22
Static Protection Measures...............................................................................................................22
Acoustics..........................................................................................................................................23
Facility Characteristics..........................................................................................................................23
Floor Loading..................................................................................................................................23
Floor Loading Terms..................................................................................................................23
Raised Floor Loading.................................................................................................................24
Average Floor Loading...............................................................................................................24
Typical Raised Floor Site............................................................................................................24
Windows..........................................................................................................................................25
Space Requirements..............................................................................................................................25
Delivery Space Requirements..........................................................................................................25
Operational Space Requirements....................................................................................................25
Floor Plan Grid................................................................................................................................26
Power Plug Configuration....................................................................................................................26
Conversion Factors and Formulas........................................................................................................29
Example of an Installation Schedule.....................................................................................................30
Sample Site Inspection Checklist..........................................................................................................30
Delivery Survey....................................................................................................................................32
Glossary............................................................................................................................35
Index.................................................................................................................................39
4 Table of Contents

List of Figures
1-1 Raised Floor Metal Strip Ground System......................................................................................14
1-2 C20 Male Receptacle (at Power Supply)........................................................................................27
1-3 C19 Female Plug (on One End of the Power Cord).......................................................................27
1-4 Unterminated Plug........................................................................................................................27
1-5 L6-20 Plug......................................................................................................................................27
1-6 IEC 309 Plug..................................................................................................................................28
1-7 CEE 7-7 Plug..................................................................................................................................28
1-8 L6-30 Plug......................................................................................................................................28
1-9 NEMA 5-20P Plug (left) and receptacle (right).............................................................................28
1-10 ISI 32 Plug......................................................................................................................................28
1-11 GB 1002 Plug..................................................................................................................................29
1-12 L6-20 Power Cable.........................................................................................................................29
1-13 Delivery Survey (Part 1)................................................................................................................33
1-14 Delivery Survey (Part 2)................................................................................................................34
5

List of Tables
1-1 Maximum Contaminant Gas Levels..............................................................................................19
1-2 Effect of Humidity on ESD Charge Levels....................................................................................22
1-3 Floor Loading Term Definitions....................................................................................................23
1-4 Typical Raised Floor Specifications...............................................................................................24
1-5 Product Technical Requirements Based on Customer Environments..........................................25
1-6 Customer and HP Information......................................................................................................31
1-7 Site Inspection Checklist................................................................................................................31
6 List of Tables

1 General Site Preparation Guidelines
This guide contains recommendations and best practices to improve site efficiency and tolerance
before installing or operating an HP high-end or mid-range server system. This general
information is intended for different server models and customer sites around the world and is
not a substitute for recommendations or requirements from the manufacturer of a specific product.
NOTE: See the specific server service guide for the guidelines required to support the specific
server.
The following information provides general principles and practices to consider before installing
or operating the system. These guidelines apply to all customer environments that an HP product
is likely to be installed in:
• Controlled computer room
• Controlled office
• Uncontrolled office/home
• Light industrial
• Mobile/portable
However, the implementation of these guidelines will vary from customer to customer and from
one environment to another.
Electrical Factors
Synopsis
AC Electrical Distribution System
HP recommends use of an electrical distribution system that exceeds normal electrical guidelines.
This recommendation is based on experiences with HP customers who have a low occurrence
of unexpected interruptions. As your system availability needs increase, these recommendations
become more important.
Recommended electrical distribution hardware includes receptacles, AC wiring, conduits, and
breakers that are sized for maximum-rated loads, rather than for typical loads. Do not exceed 75
feet (23 m) between the receptacle and nearest X0 bond and the transformers because connection
points can become loose over time and subject to loading problems.
HP recommends using a higher input voltage to the stepdown transformer within 75 feet (23
m). For example, if 480-volt current is available in the building, ensure that distribution
transformers in the server room are 480/208-volt stepdown. In an optimum electrical distribution
system:
• Electrical infrastructure is rated for maximum load.
• The distance from a receptacle to power source X0 is less than 75 feet (23 m).
• There are no daisy-chained receptacles or hot, neutral, or ground wires.
• The system is sourced from higher distribution voltages.
AC Power Quality Devices
HP products have a wide range of voltage tolerances. In general, approximately 10% of the
nominal voltage is sufficient for the marked electrical-rated voltage. The best operating margin
is in the middle of this range but your business needs will dictate the risk you can withstand.
Although utility-fed AC power is usually error free, your particular building or area might be
subject to local problems.
Electrical Factors 7

Use uninterruptible power supplies (UPSs), backup generators, auto transfer devices,
floor-mounted distribution transformers (less than 75-foot distances), and other alternatives for
critical systems and applications demanding high availability. To ensure sufficient power quality,
keep in mind:
• The best voltage operating margin is in the middle of the distribution range.
• High availability equipment should have UPS sourcing and dedicated breakers.
• A few large UPSs provide more protection than numerous smaller cabinet UPSs.
UPS Recommendations
Use online versus offline UPSs for the highest availability environment. HP does not recommend
the practice of sourcing a cabinet UPS from a room UPS as this can result in increased costs
without providing more system availability. Indeed, this practice can introduce more system
downtime than just a room-level or system-level UPS. UPSs that are compatible with present-day
technology generally use pulse width modulation (PWM) and have ratings that are appropriate
for a nonlinear load.
Power Consumption
Safety and regulatory labels on computer equipment list the ratings for maximum power
consumption conditions. Even though you will not normally reach maximum conditions, size
all electrical distribution infrastructures to meet maximum conditions. It is better to rate up rather
than down. For example, if the marked electrical voltage is 15 amperes (A) on a server, depending
on your local electrical code, the electrical infrastructure should include 20A receptacles, 20A
sized wiring, and 20A breakers. Undersizing the wiring might save costs in the beginning, but
it will cause problems as infrastructure grows.
Average-sized wiring can be used with power quality devices, such as UPSs, but not with the
electrical infrastructure.
In determining the power requirements:
• Size electrical infrastructure for maximum-rated consumption.
• Size air-conditioning and UPSs with typical ratings, but realize that overloading might take
place with additional growth of the infrastructure.
NOTE: Set cooling for the maximum-rated power output of the room, and develop a growth
plan for the cooling infrastructure.
Grounding Systems
WARNING! Follow electrical code when connecting equipment AC power ground wire to the
AC distribution point. Failure to properly ground the equipment or the floor can lead to shock
hazard.
HP computer hardware has been tested only on systems where protective earth is integral to the
electrical distribution system. This grounding is crucial for personnel safety and for maximum
equipment availability and use. Observe the following precautions:
• Neutral and ground wires have specific uses. Do not interchange them.
• Do not use conduit grounds in place of a separate grounding conductor to each receptacle.
• Size ground wires to be equal to the power source wires.
• Do not daisy chain phase, neutral, and ground wires.
• If the system is on raised flooring, use a 2-foot by 2-foot (61-cm by 61-cm) grounding grid.
8 General Site Preparation Guidelines

Comprehensive Discussion
IMPORTANT: Electrical practices and suggestions in this guide are based on North American
practices. For regions and areas outside North America, local electrical codes take precedence
over North American electrical codes.
For example, the recommendation that the Protective Earth (PE) conductor be green with a yellow
stripe, is a European Union (EU) directive. North American local electrical inspectors will accept
a ground wire if the color is green with a yellow stripe.
Local authority has jurisdiction (LAHJ) and should make the final decision regarding adherence
to region-specific or area-specific electrical codes and guidelines.
The proper design and installation of a server power distribution system requires specialized
skills. Those responsible for this task must have a thorough knowledge of appropriate electrical
codes and the limitations of the power systems for computer and data processing equipment.
In general, a power distribution system should exceed the requirements of most electrical codes.
A good design, when coupled with proper installation practices, produces the most trouble-free
operation.
A detailed discussion of power distribution system design and installation is beyond the scope
of this guide. However, electrical factors relating to power distribution system design and
installation must be considered during the site preparation process.
The following electrical factors are discussed in this section:
• Computer room safety
• Power consumption
• Electrical load requirements (circuit breaker sizing)
• Power quality
• Distribution hardware
• System installation guidelines
Computer Room Safety
WARNING! The safety of personnel must be a paramount consideration when performing the
following recommendations. Failure to comply can create life-threatening scenarios.
Inside the computer room, fire protection and adequate lighting when servicing equipment are
important safety considerations. Federal and local safety codes govern computer installations.
Fire Protection
The National Fire Protection Association’s Standard for the Protection of Electronic Computer
Data Processing Equipment, NFPA 75, contains information on safety monitoring equipment
for computer rooms.
Most computer rooms are equipped with the following fire protection devices:
• Smoke detectors
• Fire and temperature alarms
• Fire extinguishing system
• Air Handling (Plenum) space that is segmented from the remainder of the building
Additional safety devices are:
• Circuit breakers
• An emergency power cutoff switch (located at the computer room exit door)
• Devices specific to the geographic location (such as earthquake protection)
Electrical Factors 9

Fire Suppression
Though fires in computer rooms are rare, they are a safety and business consideration. Use
gaseous agents as primary fire control with water as a backup system. Gaseous agents include
CO2and Halon substitutes, like Intergen. Where fire suppression using water is dictated, use
dry pipe water valving with suitably rated temperature heads. Dry pipe water valving lowers
the business risks associated with accidental water pipe discharge.
Lighting Requirements for Equipment Servicing
Adequate lighting and utility outlets in a computer room reduce the possibility of accidents
during equipment servicing. Safer servicing is also more efficient and, therefore, less costly. For
example, adequate lighting reduces the chances of connector damage when cables are installed
or removed.
The minimum recommended illumination level is 70 foot-candles (756 lumens per square meter)
when the light level is measured at 30 inches (76.2 cm) above the floor.
Cabinet Recommendations
Use third party cabinets whose product designs have been carefully considered with the following
attributes:
• Strength
• Airflow considerations
• Cabling restrictions
Seismic or earthquake resistance can also be an important attribute in certain parts of the world.
Working Space for Server Access
The recommended working space for performing maintenance is 3 feet (0.9144 m) from either
side of, in front of, or behind the server. The work space must permit at least a 90-degree opening
of equipment doors or hinged panels. When planning for the working-space area, consider
whether access to the server will be at the front, the side, or the rear of the server.
Power Consumption
Power consumption can be divided into two broad categories:
• Marked electrical amperage, which is listed on the required safety and regulatory labels,
generally represents a “worst case” scenario that the customer cannot measure. Use this
amperage to size the electrical infrastructure.
• Typical consumption, which is measured under normal circumstances, should be used only
in customer calculations with UPS and air-conditioning sizing where remaining capacities
are needed.
In addition to the HP server hardware, you must consider any peripheral equipment that will
be installed during initial installation or a later update. See the safety and regulatory labels on
equipment or applicable product-specific documentation for such devices to determine the power
required to support these devices.
10 General Site Preparation Guidelines

NOTE: Peripheral equipment should have dedicated breakers.
Electrical Load Requirements (Circuit Breaker Sizing)
IMPORTANT: Local authority has jurisdiction (LAHJ) must determine the final decision regarding
adherence to country-specific electrical codes and guidelines.
It is good practice to derate power distribution systems for the following reasons:
•To avoid nuisance tripping from load shifts or power transients, do not run circuit protection
devices continuously above 80% of their root-mean-square (RMS) current ratings.
• Safety agencies derate most power connectors to 80% of their RMS current ratings.
Power Quality
HP servers operate over a wide range of voltages and frequencies. (See the HP Corporate Power
Standard HP-00005-03 at http://standards.corp.hp.com/smc/hpstd/pdf/F-HP0000503.pdf.) The
servers are tested and shown to comply with EMC Specification EN50082; however, damage can
occur if these ranges are exceeded. Severe electrical disturbances can surpass the design
specifications of the equipment.
Sources of Voltage Fluctuations
Voltage oscillations affect the quality of electrical power. Common sources of these disturbances
are:
• Fluctuations occurring within the facility’s distribution system
• Utility service low-voltage conditions (such as sags or brownouts)
• Wide and rapid variations in input voltage levels
• Wide and rapid variations in input power frequency
• Electrical storms
• Large inductive sources (such as motors and welders)
• Faults in the distribution system wiring (such as loose connections)
• Microwave, radar, radio, or cell phone transmissions
Power System Protection
Protect the server from the many sources of these electrical disturbances by using:
• A dedicated power distribution system
• Power-conditioning equipment
• Over- and under-voltage detection and protection circuits
• Screening to cancel the effects of undesirable transmissions
• Lightning arresters on power cables to protect equipment against electrical storms
Precautions are taken during power distribution system design to provide immunity to power
outages of less than one cycle. However, testing cannot conclusively rule out loss of service.
Adherence to the following guidelines provides the best possible performance of power
distribution systems for HP computer equipment:
• Dedicated power source—Isolates a server power distribution system from other circuits in
the facility.
• Missing-phase and low-voltage detectors—Shut equipment down automatically when a
severe power disruption occurs. For peripheral equipment, these devices are recommended
but optional.
• Online UPS—Keeps input voltage to devices constant and should be considered if outages
of one-half cycle or more are common.
Electrical Factors 11

Refer to qualified contractors or consultants for each situation.
Distribution Hardware
This section describes wire selection and the types of raceways (electrical conduits) used in the
distribution system.
Wire Selection
Use copper conductors instead of aluminum conductors. Aluminum’s coefficient of expansion
differs significantly from that of other metals used in power hardware. Because of this difference,
aluminum conductors can cause connector hardware to work loose, overheat, and fail.
Raceway Systems (Electrical Conduits) (LAHJ)
Raceways form part of the protective ground path for personnel and equipment. They protect
the wiring from accidental damage and also provide a heat sink for the wires.
The following types are acceptable:
• Electrical metallic tubing (EMT)— thin-wall tubing
• Rigid (metal) conduit
• Liquidtight with RFI shield grounded (most commonly used under raised floors)
• Armored
Building Distribution
Place building feeders and branch circuitry in rigid metallic conduits with proper connectors (to
provide ground continuity). Ensure that all conduits that are exposed and subject to damage are
constructed of rigid galvanized steel.
Grounding Systems
HP systems are tested and certified only with grounding systems in which a neutral return path
and a protective earth are separate conductors without any inserted impedances. Additionally,
protective earth and return neutral are shorted together at the X0 bonding junction on the
secondary side of the newly derived power source.
IT Power System
This product has not been evaluated for connection to an IT power system (an AC distribution
system having no direct connection to earth according to IEC 60950).
A server requires two methods of grounding:
• Power distribution safety
• High-frequency intercabinet
Power Distribution Safety Grounding (LAHJ)
The power distribution safety grounding system connects various points in the power distribution
system to earth ground using green (green/yellow) wire ground conductors. To protect computer
room personnel against shock hazards from current leakage and fault conditions, tie the ground
connections to metal chassis parts.
Power distribution systems consist of several parts that should be solidly interconnected to
provide an equipotential ground to all points.
Main Building Electrical Ground
The main electrical service entrance equipment must have an earth ground connection as required
by applicable codes. Such connections as a grounding rod or building steel provide an earth
ground.
12 General Site Preparation Guidelines

Electrical Conduit Ground
All electrical conduits must be made of rigid metallic conduit that is securely connected together
or bonded to panels and electrical boxes so as to provide a continuous grounding system.
Power Panel Ground
Ground each power panel to the electrical service entrance with green (green/yellow) wire ground
conductors. Size the green (green/yellow) wire ground conductors per applicable codes (based
on circuit-over-current device ratings). The PE (Protective Earth) wire gauge may be a larger
diameter wire but not a smaller diameter wire than the AC input power distribution wire.
NOTE: The green wire ground conductor mentioned above can be a black wire with green
tape. (LAHJ)
Computer Safety Ground
Ground all computer equipment with the green (green/yellow) wire included in the branch
circuitry. Connect the green (green/yellow) wire ground conductors to the appropriate power
panel and size them per applicable codes (based on circuit-over-current device ratings).
Dual Power Source Grounding
The use of dual power might create an electrical potential that can be hazardous to personnel
and might cause performance issues for the equipment. When using dual power sources, measure
voltage potentials with a high impedance digital multi-meter (DMM).
Dual power sources might originate from two different transformers or two different UPS devices.
Measure voltage potentials from ground pin to ground pin of these sources and verify them to
be at or near 0.0 V. Investigate voltage levels that measure above 3.0 V because increased voltages
can be hazardous to personnel.
Cabinet Performance Grounding (High-Frequency Intercabinet Ground)
Some safety power distribution wires are too long and too inductive to provide adequate
high-frequency return paths. For sufficient protection, signal interconnects between system
cabinets might need high-frequency ground return paths in addition to the safety or power
distribution system 50–60Hz grounding system. HP recommends the use of a properly installed
signal reference grid (SRG) also bonded to the 50–60Hz grounding system.
WARNING! Do not use cabinet-to-floor ground straps in place of a properly installed safety
(50–60Hz) grounding system, nor in place of a properly installed Signal Reference Grid. An
improperly installed grounding system can present a shock hazard to personnel.
Connect any power panel(s) ground buses and transformers XO bond that are in close proximity
to the computer equipment to the site grounding grid. Methods of achieving a sufficiently
high-frequency ground grid are described in the next sections.
Raised Floor “High-Frequency Noise” Grounding
If you use a raised floor system, install a complete SRG to maintain equal potential over a broad
band of frequencies. Connect the grid to the equipment cabinet and electrical service entrance
ground at multiple connection points by using a minimum #6 AWG (16 mm) wire ground
conductor. Figure 1-1 (page 14) illustrates a metallic strip grounding system.
Electrical Factors 13

IMPORTANT: Regardless of the grounding connection method used, you must ground the
raised floor as an absolute safety minimum.
HP recommends the following approaches to create an effective and safe 2-foot by 2-foot signal
reference grid:
•Good—Use the raised floor structure as a ground grid. In this case, the floor must be designed
as a ground grid with bolted down stringers and corrosion-resistant plating (to provide low
resistance and attachment points for connection to service entrance ground and HP computer
equipment). The use of conductive floor tiles with this style of grid further enhances ground
performance. The structure needs to be mechanically bonded to a known good ground point.
•Better—Add a grounded #6 AWG (16mm) minimum copper wire grid mechanically clamped
to floor pedestals and properly bonded to the building or site ground.
• Best—Add a grounding grid to the subfloor. Build the grounding grid with copper strips
mounted to the subfloor. Use strips that are 0.032 inches (0.08 cm) thick and a minimum of
3.0 inches (8.0 cm) wide.
Connect each pedestal to four (4) strips using 1/4-inch (6.0-mm) bolts tightened to the
manufacturer’s torque specification.
Figure 1-1 Raised Floor Metal Strip Ground System
Equipment Grounding Implementation Details
Connect all HP equipment cabinets to the site ground grid as follows:
1. Check that the braid contact connection points are free of paint or other insulating material
and treated with a contact enhancement compound (similar to Burndy Penetrox).
14 General Site Preparation Guidelines

2. Check that the braid contact on each end of the ground strap consists of a terminal and
connection hardware (a 1/4-inch (6.0-mm) bolt, nuts, and washers).
3. Attach one end of each ground strap to the applicable cabinet ground lug.
4. Attach the other end to the nearest pedestal base (raised floor) or cable trough ground point
(nonraised floor).
5. After achieving a safe and effective 50–60Hz grounding system and a safe and effective SRG,
then consider cabinet-to-floor grounding. HP does not require this step.
System Installation Guidelines
This section contains information about installation practices and highlights some common
installation hazards. It addresses both power and data communications cable installations, and
highlights installation.
NOTE: In domestic installations, install approved receptacles before the HP equipment arrives.
See the appropriate installation guide for installation procedures.
Wiring Connections
Expansion and contraction rates vary among different metals. Therefore, the integrity of an
electrical connection depends on the restraining force applied. Connections that are too tight
compress or deform the hardware and cause it to weaken. This usually leads to high impedance,
preventing circuit breakers from tripping when needed. High impedance can also contribute to
a buildup of high-frequency noise.
CAUTION: Connections that are too loose or tight can have a high impedance which cause
serious problems, such as erratic equipment operation. A high-impedance connection overheats
and sometimes causes fire or high temperatures that can destroy hard-to-replace components,
such as distribution panels or system bus bars.
Wiring connections must be properly torqued. Many equipment manufacturers specify the proper
connection torque values for their hardware. See the safety requirements provided by your wire
manufacturer.
Ground connections must be made only on a conductive, nonpainted surface. When equipment
vibration is present, lock washers must be used on all connections to prevent connection hardware
from working loose.
Data Communications Cables
Power transformers create high-energy fields in the form of electromagnetic interference (EMI).
Heavy foot traffic can create electrostatic discharge (ESD) which can damage electronic
components. Route data communications cables away from these areas and use shielded data
communications cables that meet approved industry standards to reduce the effects of external
energy fields.
Environmental Elements
Synopsis
Air Quality
Proper computer room preparation improves air quality. It provides a return on investment by
making a system more stable and by decreasing unexpected downtime. HP recommends putting
appropriate effort into maximizing electrical and air-conditioning efficiency to ensure higher
reliability to meet business needs.
Environmental Elements 15

HP temperature and humidity recommendations follow newly established industry standards
in the following operating ranges:
• Temperature of 20–25 °C (68–77 °F)
• Humidity of 40%–55% relative humidity
• Filtration at 35%–55% spot efficiency per American Society of Heating, Refrigerating, and
Air-Conditioning Engineers (ASHRAE)
• Air-conditioning heat load limits at 80% of total heating, ventilation, and air-conditioning
(HVAC) capacity
Airflow
A public misperception exists that cool, ambient air is consistent throughout a datacenter. That
is, if the temperature of the room is measured at 20 °C (68 °F), then the equipment should be
stable. In reality, microclimates can exist in various parts of the room such that generated heat
in the equipment might not efficiently make its way out. Microclimates are difficult to detect
and prove; therefore, prevent microclimates by encouraging a high rate of airflow from source
to intake of HVAC and uniform distribution of the heated air. Underflow blockages, such as
cabling and piping, can disrupt the airflow predictability. Improperly positioned floor vent tiles
or equipment can create air dams and decrease airflow. Follow these precautions to ensure proper
airflow:
• Use a heat load to 80% of total HVAC capacity to maintain a thermal safety margin.
• Place vented floor tiles only in heat load areas.
• Do not place vented floor tiles within two floor tiles of HVAC (thermal short circuit).
• Do not place heat loads closer than two floor tiles of HVAC.
• Be sure the maximum distance from the HVAC to the heat load is less than 75 feet (23 m).
• Seal all cable openings as unsealed openings create a loss of static air pressure.
• Lay out equipment aisles parallel to airflow; not perpendicular to it.
• Concentrate high-density heat loads in a tightly controlled area. High-density loads are
equivalent to one cabinet of 3 kilowatts or more.
•Maintain airspeed through vent tiles at more than 500 feet per minute (152 meters per minute)
but at less than 700 feet per minute (213 meters per minute) for high-density cooling.
Equipment Orientation
Data center equipment orientation, or heat load, must encourage sufficient airflow. If exhausted
heat must move over or around a cabinet, air vortexes might be created, resulting in airflow
inefficiency throughout the data center and inside the equipment. Equipment might develop
internal hot spots, resulting in sluggish performance or even system failure.
Rather than designing a layout to maximize a planning grid worksheet whitespace, create “hot”
and “cold” aisles. In a hot aisle, equipment is oriented so that exhaust vents face other exhaust
vents. In a cold aisle, intake vents face other intake vents. Place vent tiles in the cold aisles, with
few to no vent tiles in the hot aisle. Position equipment in parallel to encourage the lowest air
resistance and turbulence. Consider the following when determining equipment orientation:
• Orient equipment in parallel to airflow.
• Place cabling in such a way as to aid airflow rather than impede it.
• Arrange equipment to form hot and cold aisles.
• Use vent tiles to control airflow in heat load areas.
• Place vent tiles in cold aisles.
• Place higher heat load devices at floor level.
16 General Site Preparation Guidelines

Electrostatic Discharge (ESD): Source of Greatest Failure Rate Without Detection
Computer equipment is increasing in processor and memory density even as size continues to
decrease. These smaller, more densely packed pieces of equipment are at greater risk to damage
from electrostatic discharge. ESD created by the human body can be any voltage from zero, some
voltages beginning at twenty five volts (25V). ESD that is felt by the human body can be 3,000
volts.
Contemporary electronic technology can be damaged or upset by voltages far lower than the
human experience would indicate.
HP recommends building this consideration into your designs for floor coverings, humidity
control, airflow, dust control, and personnel traffic. Consider the following precautions to prevent
or minimize ESD:
• Use antistatic flooring.
• Maintain humidity at 40%–55% relative humidity.
• Follow airflow recommendations.
• If raised flooring is present, use a 2-foot by 2-foot (61-cm by 61-cm) grounding grid.
• Always use appropriately sized AC power ground wires.
• Limit personnel traffic to two floor tiles away from equipment.
Cellular Telephone and Wireless Usage
HP recommends not using cell phones within a data center, especially within 9.8 feet (3 m) of
any high-availability equipment.
Comprehensive Discussion
The following environmental elements can affect a server installation:
• Computer room preparation
• Airflow
• Cooling requirements
• Humidity level
• ESD prevention
• Acoustics
Computer Room Preparation
Consider the following guidelines to prepare a computer room for a server:
• Locate the computer room away from the exterior walls of the building to avoid the heat
gain from windows and exterior wall surfaces.
• When exterior windows are unavoidable, use windows that are double- or triple-glazed
and shaded to prevent direct sunlight from entering the computer room.
• Maintain the computer room at a positive pressure relative to surrounding spaces.
• Use a vapor barrier installed around the entire computer room envelope to restrain moisture
migration.
• Caulk and vapor seal all pipes and cables that penetrate the envelope.
• Use a raised floor system at least 18 inches (45.72 cm) high for the minimum favorable room
air distribution to ensure good static air pressure beneath the flooring (under floor
distribution).
• Ensure a minimum clearance of 12 inches (30.48 cm) between the top of the server cabinet
and the ceiling to allow for return airflow and to ensure that all ceiling tiles are in place,
except where fire sprinkler heads call for greater clearance.
• Allow 18 inches (45.72 cm) (or local code minimum clearance) from the top of the server
cabinet to the fire sprinkler heads.
Environmental Elements 17

Airflow
Ensure that separate hot and cold aisles are parallel to airflow patterns.
•This recommendation causes cooling air to be released into cold aisles, where opposing rows
have intake grills oriented.
• Ensure that opposing row exhaust grills face each other, without cooling air.
• A parallel orientation encourages low impedance airflow back to the HVAC.
• Route cables underneath the floor to be parallel to the airflow to prevent airdams, if raised
flooring is used.
• Keep air throws from HVAC equipment to the heat loads they serve within 75 feet (22.86
m) of each other.
Row Orientation
Row orientation has an impact on the airflow, temperature, particulate contamination, and power
distribution of the environment. Consider the following when planning equipment layout:
• Use hot aisle (exhaust) and cold aisle (intake) orientation.
• Route the airflow (air conditioned supply and return) to be parallel to the aisleways.
•Adhere to the temperature and humidity standards located at: http://standards.corp.hp.com/
smc/hpstd/pdf/F-HP0000501.pdf.
HP product specifications for temperature and humidity are measured at 1.9 inches (5.0 cm)
from air intake center of device.
Dust and Pollution Control
Computer equipment can be adversely affected by dust and microscopic particles in the site
environment.
Specifically, disk drives, tape drives, and some other mechanical devices can have bearing failures
resulting from airborne abrasive particles. Dust might also blanket electronic components such
as printed circuit boards, causing premature failure due to excess heat or humidity buildup on
the boards. Failures to power supplies and other electronic components can be caused by
metallically conductive particles, including zinc whiskers. These metallic particles are conductive
and can short circuit electronic components. Use every effort to ensure that the environment is
as dust- and particulate-free as possible. See “Metallic Particulate Contamination” (page 19) for
additional details.
Smaller particles can pass through some filters and cause short life cycles in mechanical parts.
Prevent small dust particles from entering the computer room by maintaining the air-conditioning
system at a high static air pressure level.
Other sources of dust, metallic, conductive, abrasive, and microscopic particles can be present.
Some sources of these particulates are:
• Subfloor shedding
• Raised-floor shedding
• Ceiling-tile shedding
These particulates are not always visible to the naked eye. One method to determine their possible
presence is to inspect the underside of the tiles. There are two types of flooring:
a. galvanized – shiny – hot dipped: least susceptible for whiskers
b. painted – dull – electroplating: most susceptible for whiskers
18 General Site Preparation Guidelines

Keep the computer room clean by following these guidelines:
•Establish a no-smoking policy. Particulates of cigarette smoke will not improve the operation
or reliability of surrounding equipment.
• Locate printers and paper products in a separate room to eliminate paper particulate
problems.
•Establish a no-eating-or-drinking policy. Spilled liquids can cause short circuits in equipment
such as keyboards.
• Use a dust-absorbent cloth mop rather than a dry mop to clean tile floors.
• Use only HP-approved cleaners.
In addition to dust and microscopic particles, chemical contaminants in the air can also damage
electronics. Chemical contaminant levels in customer environments for HP hardware products
must not exceed G1 (mild) levels of Group A chemicals at any time, as described in the current
version of ISA–71.04–1985 Environmental Conditions for Process Measurement and Control Systems:
Airborne Contaminants.
See http://www.isa.org/ for more information.
If the environment does not meet G1 levels, third party experts in remediation should be engaged
to help bring the site into compliance. This work will include verifying contaminant levels and
sources, as well as determining the most effective remediation techniques. Those may include
filtration and abatement of the environment by qualified professionals to remove the contaminants.
Table 1-1 Maximum Contaminant Gas Levels
Maximum Group A contaminant gas levels in customer environments for class G1 in Table 3 of ISA–71.04–1985 .
Maximum Parts per Billion (ppb)Contaminant Gas
3H2S
10SO2, SO3
1Cl2
50NOx
These values have been included for convenience and reflect the gas concentration levels in Table 3 of ISA–71.04–1985.
The complete ISA document is available through the ISA website at:
http://www.isa.org/.
Metallic Particulate Contamination
Metallic particles can be especially harmful around electronic equipment. This type of
contamination can enter the data center environment from a variety of sources, including but
not limited to raised floor tiles, worn air-conditioning parts, heating ducts, rotor brushes in
vacuum cleaners, or printer component wear. Because metallic particles conduct electricity, they
have an increased potential for creating short circuits in electronic equipment. This problem is
exaggerated by the development of more dense circuitry of electronic equipment.
Over time, very fine whiskers of pure metal can form on electroplated zinc, cadmium, or tin
surfaces. If these whiskers are disturbed, they can break off and become airborne, possibly causing
failures or operational interruptions. For more than 50 years, the electronics industry has been
aware of the relatively rare but possible threat posed by metallic particulate contamination.
During recent years, concern has increased regarding metallic particulate contamination in
computer rooms where these conductive contaminants are formed on the bottom of some raised
floor tiles.
Although this problem is relatively rare, it can be an issue within your computer room. Because
metallic contamination can cause intermittent or permanent failures on your electronic equipment,
Environmental Elements 19

HP strongly recommends to test your site for metallic particulate contamination before installing
electronic equipment.
Cooling Requirements
Air-conditioning equipment requirements and recommendations are described in the following
sections.
Basic Air-Conditioning Equipment Requirements
The cooling capacity of the installed air-conditioning equipment for the computer room must
be sufficient to offset the computer equipment dissipation loads, as well as any space envelope
heat gain. This equipment must include:
• Air filtration
• Cooling or dehumidification
• Humidification
• Reheating
• Air distribution
• System controls
When calculating cooling requirements, include the heat generated by lighting and personnel.
For example, a person dissipates about 450 Btus per hour while performing a typical computer
room task.
At altitudes above 10,000 feet (3,048 m), the lower air density reduces the cooling capability of
air-conditioning systems. If your facility is located above this altitude, you might need to modify
the recommended temperature ranges. For each 1,000 foot (305 m) increase in altitude above
10,000 feet (up to a maximum of 15,000 feet (4,572 m)), subtract 0.83 °C (34 °F) from the upper
limit of the temperature range.
Air-Conditioning System Guidelines
Use the following guidelines when designing an air-conditioning system and selecting the
necessary equipment:
• The computer room air-conditioning system should be capable of operating 24 hours a day,
365 days a year. It should also be independent of other systems in the building.
• Consider the long-term value of server availability, redundant air-conditioning equipment,
or capacity.
• The system should be capable of handling any future server expansion.
• Air-conditioning equipment air filters should have a minimum rating of 45% (based on
ASHRAE Standard 52-76, Dust Spot Efficiency Test).
• Introduce only enough outside air into the system to meet building code requirements (for
human occupancy) and to maintain a positive air pressure in the computer room.
Air-Conditioning System Types
The following three air-conditioning system types are listed in descending order of preference:
1. Complete self-contained package units with remote condensers. These systems are available
with up or down discharge and are usually located in the computer room.
2. Chilled water package unit with remote chilled water plant. These systems are available
with up or down discharge and are usually located in the computer room.
3. Central station air-handling units with remote refrigeration equipment. These systems are
usually located outside the computer room.
20 General Site Preparation Guidelines