After controlling the availability and stability of electrical power, the next concern in system environmental are about air condition, fire and water exposures. Data center need special condition in temperatures and humidity. Water and fire existence in system premises, surely cause damage on system hardware. In simple conclusion, lack control in those aspects will short computer systems life.

Controlling Air

The computer installation requires heating, ventilation, and air-conditioning. Electronic equipment performs well in cold conditions; however, magnetic media should not be allowed to freeze. Ventilation is necessary for cooling computer equipment. Physical damage occurs if the computer circuitry sustains extended use at temperatures of 104 degrees or higher. Physical damage will also occur if the internal electronic circuitry exceeds 115 degrees during operation. Air-conditioning is also used to control humidity. Humidity will control static electricity that could damage electrical circuits. The ideal humidity for a computer room is between 35 percent and 45 percent at 72 degrees. This will reduce the atmospheric conditions that would otherwise create high levels of static electricity.

Controlling Fire and Smoke

The data center and records storage area should be equipped for fire, smoke, and heat detection. Unheated areas may need to be monitored for freezing conditions. A fire-detection system activates an alarm to initiate human response. A fire-detection system may also activate fire suppression with or without the discharge of water or chemicals. There are three basic types of fire detectors, using smoke detection, heat detection, or flame detection:

• Smoke detection Uses optical smoke detectors or radioactive smoke detection
• Heat detection Uses a fixed temperature thermostat (which activates above 200 degrees), or rapid-rise detection (which activates the alarm if the temperature increases dramatically within a matter of minutes)
• Flame detection Relies on ultraviolet radiation from a flame or the pulsation rate of a flame

Fire suppression is the next step after fire detection. A fire-suppression system may be fully automated or mechanical. There are three basic types of fire-suppression systems:

1. Wet pipe system The wet pipe system derives its name from the concept of water remaining inside the pipe. Most sprinkler heads in a ceiling-based system are mechanical. Each sprinkler head is an individual valve held closed by a meltable pin. A fire near the sprinkler head will melt the pin, and the valve will open to discharge whatever is in the pipe. This type of system can burst because of a freeze, or leak due to corrosion, which would create an unscheduled discharge.
2. Dry pipe system The dry pipe system is an improvement over the wet pipe for two reasons. First, the pipe is full of compressed air rather than water prior to discharge. When the valve opens, there is a delay of a few seconds as the air clears from the line. The water will discharge after the air is purged. This leads us to the second advantage. The flow of rushing air can trigger a flow switch to activate the EPO switch to kill electrical power. Equipment will shut off during the few seconds before the water is discharged. This will reduce the amount of damage to computer equipment. Special computer cabinets are made to shed water away from electronic hardware mounted inside.?
3. Dry chemical system Dry chemical systems are frequently used in computer installations because dry chemicals avoid the hazards created by water. The dry chemical system uses a gas such as FM-200 or NAF-S-3 to extinguish fire. Gaseous halon is no longer used because it is a chlorofluorocarbon (CFC) that destroys the Earth’s ozone layer (1994 international environmental accord). The exception is aircraft and ships. Fires occurring while in flight or at sea could be devastating with tragic loss of life. All former halon installations in computer rooms should have been converted to FM-200 or an equivalent dry chemical. When electronic sensors detect a fire condition, the dry chemical system will discharge into the room.

Special administrative controls are necessary with dry chemical systems. Maintenance personnel must never lift floor tiles or move ceiling tiles while the dry chemical system is armed. Floating particles of dust can activate a discharge of dry chemicals. Humans should not inhale the gas used in dry chemical systems because it may be lethal. A dry chemical discharge introduces a great deal of air pressure into the room within seconds. Fragile glass windows may shatter during discharge, creating a temporary airborne glass hazard.

You need to be aware that a water pipe system may be required even if a dry chemical system is installed. Fire safety codes can require wet pipe systems throughout the building, without exception. Some building owners will not allow the tenant to alter existing fire-control systems. The dry chemical system would then have to be installed in parallel to the existing water-based system.

Controlling Water

Water is discharged from air-conditioning or cooling systems and usually runs to a drain located under the raised floor. Water-detection systems are necessary under the floor to alert personnel of a clogged drain or plumbing backup. Water-detection sensors also may be placed in the ceiling to detect leakage from pipes in the roof above. It is common for water pipes to be located over a computer room directly above the ceiling tiles or higher floors. Water can even cascade down inside the building from the roof.  To minimize risk, the organization should have a policy prohibiting food, liquids, and smoking in the computer facility.

Source:  CISA® Study Guide Second Edition (chapter 7) by David L. Cannon

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