Clean-Agent System After Data Center Modifications
A data center occupies a 2,500 ft³ room protected by a heptafluoropropane clean-agent system designed to deliver a 7.5% concentration at 20°C. The room has a raised floor, a suspended ceiling, and one exit door with a self-closer. Since commissioning, operators have added 14 server racks, reducing the free volume to about 2,200 ft³, and replaced the original ceiling tiles with heavier acoustic panels. The agent cylinder quantity was not changed. During a test, the door failed to latch fully and remained open about 2 inches. The system's discharge nozzle is located at the ceiling center, and the room's pressure relief damper is painted shut. No one has performed a door-fan test since the racks were added. The facility manager asks whether the system will still extinguish a fire and whether the room is safe for occupants during discharge.
1. Assess the effect of the reduced free volume on agent concentration and system performance.
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The agent mass was sized for 2,500 ft³ at 7.5%. Reducing free volume to 2,200 ft³ with the same mass raises the actual concentration by roughly 2,500/2,200, or about 14%, to around 8.5% before leakage. That may still extinguish the fire, but it can exceed the agent's no-observed-adverse-effect level and increase decomposition-product formation. Heavier ceiling tiles reduce leakage, but the painted-shut pressure relief damper can cause overpressure or prevent proper discharge. The ceiling-center nozzle may not mix agent into the raised floor and rack aisles. The system must be recalculated, not assumed adequate.
2. What enclosure and safety deficiencies must be corrected before relying on the system?
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The door must latch and the closer must be repaired; a 2-inch gap will prevent the required hold time. Clear the pressure relief damper and verify its area. Perform a door-fan test to measure enclosure leakage and confirm the hold time at the design concentration. Provide pre-discharge alarm, discharge warning signs, and occupant training. Confirm that the exit door opens in the direction of egress and is usable during discharge. Verify that the agent's safety limits are not exceeded and that the room can be evacuated before discharge.
3. What testing and documentation would you require?
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Require a door-fan integrity test, a concentration verification test, cylinder weight check, nozzle and pipe inspection, and a functional test of detection, alarm, and discharge. Recompute agent quantity for the new volume and ceiling configuration. Update the acceptance test documentation, as-built drawings, and operating procedures. Train staff on alarm response and post-discharge reentry. Schedule annual inspection and maintenance, and document every change that affects the enclosure. The facility should not rely on the system until the recalculated design and enclosure test are accepted.