What is WATER SPRAY?Water spray" systems are operationally identical to a deluge system, but the piping and discharge nozzle spray patterns are designed to protect a uniquely configured hazard.

Examples of hazards protected by water spray systems are electrical transformers containing oil for cooling or turbo-generator bearings.

NFPA-850: Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations

Identification of and Protection Against Hazards -Transformers

Oil filled main, station service and start-up transformers not meeting the separation or fire barrier recommendations or as determined by the Fire Protection Design Basis should be protected with automatic water spray or foam-water spray systems.

NFPA-15:Standard for Water Spray Fixed Systems for Fire Protection

Defines a water spray system as:

an automatic or manually actuated fixed pipe system connected to a water supply and equipped with water spray nozzles designed to provide a specific water discharge and distribution over the protected surfaces or area.

How Does a Water Spray System Work?The Deluge Valve is an integral part of a deluge system:

Specialty fire protection valveHolds water supply back behind a clapper or diaphragmWater is released via an electric or pneumatic detection system throw solenoid valve

The layout of nozzles is based upon spray characteristics:

Angle of spray and associated positioning angle.

Orifice size (how much water can be sprayed out of each nozzle.

Typical Nozzles

Manual DetectionManual detection is used as a back up for automatic detection.

Draining the system will automatically open the deluge valve.

Process and Output Cross-Zoning Cross zoning:helps reduce unwanted water dischargesDivides detectors into two zones

Water will not release unless detectors of two zones are activated.Two zones provides releasing

Different Response Stages Cross zoning:

Allows escalating responseCalls fire departmentInitiates alarm condition on building Fire Alarm SystemReleases water

Interaction with Building Fire Alarm System Water Spray System must report:

AlarmSupervisoryCommon Trouble

Inspection, Testing and Maintenance A deluge systems ITM program should be developed in accordance with NFPA 25: Standard for the Inspection, Testing and Maintenance of Water-Based Fire Protection Systems.

Detection system ITM should follow the requirements set forth in NFPA 72: National Fire Alarm and Signaling Code

Documentation of all ITM work should be meticulously maintained and readily available for review by the AHJ

Critical elements of an ITM program include:Annual tripping of deluge valve at full flow

Observation of water discharge patterns to confirm proper positioning and absence of obstructions

Verification of water flow alarms

Annual operation of annual actuation devices

Cleaning of interior of deluge valve during annual testing

Draining of system low points

Internal inspection of strainers every five years at a minimum

Summary A transformer fire is not a frequent occurrence but the impact is tremendous

In a fire the transformer will likely be destroyed immediately but damage to adjacent equipment/structures can be mitigated

The consequences of an uncontained fire include:Costly damage to the facilityLoss of revenue due to an unscheduled outageCompromising the safety of facility inhabitants

**