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FIRE PROTECTION DESIGN

INDUSTRY STANDARDS

DDC provide Fire Sprinkler Design in accordance with industry standards including Loss Prevention Council Rules, FM Global Data Sheets, NFPA Standard and BS 9251 Residential Standard.

Valve sets
Pumphouse

DESIGN CODES

We specialise in Fire Protection Design adhering to the following design codes:

  • LPC /BSEN 12845 Sprinkler Design Code.

  • FM Global Design Codes.

  • NFPA Sprinkler Design Codes.

  • BS 9251: 2020 Residential and Domestic Sprinkler Systems.

We offer the complete design of fire sprinkler systems, including Wet, Dry, Pre-action and Deluge systems.

TYPES OF FIRE PROTECTION SYSTEMS

WET SYSTEMS

The wet alarm valve is the most common arrangement of alarm valve. The pipes are filled with water under pressure and are only installed in frost resistant building areas.

Automatic sprinkler is exposed for a sufficient time to a temperature at or above the temperature rating, the heat-sensitive element breaks, allowing water to flow from the sprinkler.

 

Wet Pipe Systems have two principal functions.

  1. Acts as a non-return or check valve.

  2. Sounds an alarm when water flows.

Wet Pipe
Dry Systems_edited

DRY SYSTEMS

Dry alarm valves are most used in installations subject to freezing or hot process risks where range temperatures exceed 70°C. Dry pipe systems are typically used in refrigerated coolers, car parking areas and in unheated buildings or water sensitive areas, since dry pipe systems do not leak water.

The sprinkler piping is filled with pressurised air.

A special alarm valve is used to separate the sprinkler pipe and the water supply pipe. When one or more of the automatic sprinklers is exposed to a temperature at or above the temperature rating, it opens, allowing the air in the piping to vent from that sprinkler. When the air pressure in the piping drops, the pressure difference across the alarm valve changes. This will force the alarm valve to open, allowing water to enter the piping system. The water flow from the sprinklers is delayed until the air is vented from the sprinklers.

 

Dry pipe systems are therefore not as fast acting in the initial phase of a fire. The only delay before water is distributed via the sprinklers is from the time to vent the air from the pipe. This means that the potential for severe water damage exists. Dry pipe alarm valves should only be used where it is impractical to employ a wet pipe alarm valve and should be avoided in high hazard applications.

PRE-ACTION SYSTEMS

Pre-action alarm valves are variations on the dry pipe alarm valve. They are commonly used in sensitive areas i.e. data centres, computer rooms etc. where accidental activation is undesired. They additionally employ an independent fire detection system and control panel. The fire detection system is either used to accelerate operation of the pre-action valve by opening it in advance of a sprinkler head operation or to prevent unintentional water discharge from a damaged sprinkler head.

Preaction Systems
Dry Systems

DELUGE VALVES

The Deluge pipe alarm valve is designed to operate as a wet pipe when there is no risk of freezing and a dry valve in the winter months when there is the possibility of freezing. This is a system where all connected sprinklers are open. These sprinklers have no sensing element.

This is usually in areas where rapid fire spread is expected and often where cooling storage tanks or plant may be necessary. The open sprinklers will distribute water over the entire area. The piping is filled with atmospheric pressure, and a mechanically activated deluge valve will open in case of fire, enabling the water to fill the sprinkler pipe. The deluge valve is activated by a signal from a fire alarm system and remains open once it has been activated. The fire alarm system consists of smoke or heat detectors activating the alarm system, which opens the deluge valve.

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