AUTOMATIC SPRINKLERS

Sprinkler System

OPERATION

Automatic sprinkler system as a network of charged hose line (pipes) suspended throughout a facility and ready to deliver water through regularly spaced nozzles (sprinklers) shortly after fire starts.

Water is automatically released when sprinkler’s fusible element (metal link or glass bulb) is heated equal or above its temperature rating.

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The metal link melts or the bulb bursts, releasing the water under pressure, which hits the sprinkler’s deflector to form an umbrella-like spray pattern over the fire.

Each sprinkler operates individually.

Types of Sprinkler Systems

1. Wet-pipe System

2. Dry-pipe System

3. Pre-action System

4. Deluge System

The Wet-pipe Sprinkler System

Is the most common.The sprinkler piping is filled with water

under pressure.When the individually fused sprinklers

operate, the water immediately discharges and continues to flow until the system is shut off.

The Dry-pipe Sprinkler System

Is used in unheated areas where water in piping would be susceptible to freezing.

Instead of water, the the piping contains pressurized air.

The air holds the water behind a dry-pipe valve, which is located in heated area.

When a sprinkler operates, the drop in air pressure automatically opens the dry-pipe valve, which lets water into the pipes.

Time delay.

The Pre-action Sprinkler System

Is similar to a dry-pipe system but is considered slightly more efficient.

This system is used where an alarm in advance of sprinkler operation is desired, and where it is particularly important to prevent accidental discharge of water.

Heat or smoke detectors are installed throughout a protected area.

When a detector actuates, an automatic water control valve admits water through sprinkler piping, where it remains until a sprinkler head operates.

The Deluge System

Operates in much the same manner as the pre-action system, but with one exception:

The sprinkler heads are open (they have no fusible element) so that water will discharge from all sprinklers simultaneously, wetting down the entire protected area.

This system is used in high-hazard occupancies where the immediate application of large quantities of water is needed.

Alarms

Within each sprinkler system is an alarm.It is activated when a predetermined

amount of water flows through an alarm actuating device.

A local alarm sounds an audible signal on the premises and alert employees.

A proprietary or central station alarm sends an electrical impulse to a supervisory station.

Alarms

Types Of Sprinklers

1. Upright Standard Sprinkler

2. Pendent Standard Sprinkler

3. Dry-pendent Sprinkler

4. Sidewall Sprinkler

5. Rack Storage Sprinkler

6. Large-drop sprinkler

7. Early Suppression-Fast Response (ESFP)

8. On-off Sprinklers

Sprinkler Components

Orifice SizeTemperature RatingOccupancy (light – Moderate – Extra)Control ValvesCommodity ClassificationSprinkler Piping and SpacingWater Supply (Tanks – Muncipal -)Connections (Test conn. – siamese)

Sprinkler System Maintenance

Systems shall be properly maintained. A main drain flow test must be

performed on each system annually. The inspector's test valve shall be

opened at least every two years to assure proper operation of the system.

New systems shall have proper acceptance tests conducted including: – Flushing of underground

connections – Hydrostatic tests of system piping

Sprinkler System Maintenance

– Air-tests in dry-pipe systems – Test of drainage facilities.

Every automatic sprinkler system must be provided with at least one automatic water supply capable of providing designed water flow for at least 30 minutes.

In order to provide a maximum protection area per sprinkler and a minimum of interference to the discharge pattern, the vertical clearance between sprinklers and material below shall be at least 18 inches.