Wet Pipe Sprinkler System in Bhopal

Water fills the whole pipe network all the time, held under pressure by a jockey pump, the fire pumps or an overhead tank. Each sprinkler head is closed by a glass bulb or a solder link. When the hot gases from a fire heat a head to its rating, usually 68°C, the bulb breaks and that head alone starts to spray. Most fires are controlled by the first few heads.

At the riser sits the installation control valve: a main stop valve, the alarm valve, pressure gauges, a test and drain valve and the line to a water motor gong. When a head opens, the alarm valve's clapper lifts, water runs to the gong outside the building and to a pressure switch, and the fire alarm panel is told. Flow switches on each floor or zone show where the water is going.

Wet pipe systems are the simplest kind and the quickest to respond, because water is already at every head. They suit any space that stays above freezing. In cold stores, a dry pipe system keeps the pipes filled with air instead.

The alarm valve, also called the alarm check valve, holds water in the system, stops it flowing back and starts the alarm when a sprinkler opens. HD Fire's Model H comes in 80 to 200 NB in ductile iron, UL Listed, FM Approved and CE marked. New Age offers a UL Listed alarm check valve in 4 and 6 inch, and Tyco's AV-1-300 is rated 300 psi in DN65 to DN200.

A water motor gong rings outside the building whenever water flows through the alarm line, with no power needed. Where the supply pressure varies, a retard chamber stops surges from setting off false alarms, and pressure relief trim lets off the pressure that builds up when the pipes warm. Gauges show the pressure on both sides of the valve.

Large buildings are split into zones, each with its own control point, so the fire alarm shows the floor or area where water is flowing and one zone can be shut for work without draining the rest. The HD Fire zone control manifold brings a flow switch, test drain, pressure gauge and relief valve together in 2.5 to 8 inch, and Tyco RM-2 riser manifolds do the same on 2 to 6 inch risers. System Sensor waterflow detectors fit steel pipe from 2 to 8 inch, and its supervisory switches tell the panel if a control valve is closed.

A wet pipe system can use every type of head. Choose the type by where it is mounted, then the K factor, response and temperature the design calls for. Each page compares every model of one type:

Where pipes could freeze, such as cold stores and unheated loading bays, the pipes hold air or nitrogen under pressure instead of water. When a head opens, the air escapes, the dry pipe valve opens and water flows to the open head. We supply Tyco DPV-1 dry pipe valves in DN65 to DN150, with mechanical or electronic accelerators that open the valve sooner and air or nitrogen maintenance devices that hold the pressure. Dry-type heads stop water standing in the drop to the head.

Start with the hazard. Sprinkler standards sort buildings into hazard classes, from light hazard for offices, hotels and hospitals to ordinary hazard for shops, car parks and most factories, and higher classes for stores of flammable goods. The class sets the water density, the area each head covers and how long the water supply must last.

Then the heads: pendent heads under a false ceiling, concealed heads where the ceiling must look clean, upright heads on exposed pipes and sidewall heads where the pipe runs along a wall. Quick response heads with a 3 mm bulb are usual in offices, hotels and hospitals, and standard response heads with a 5 mm bulb in factories and stores.

Finally the water: a hydraulic calculation sizes the pipes and confirms that the pumps and tank give the design flow at the farthest heads. We do the survey, the design and drawings for the fire NOC, the installation, the pressure, flow and alarm tests, and the AMC.