A fire sprinkler system is an active fire protection measure, consisting of a water supply providing appropriate pressure and flow rate to distribution piping and exiting sprinklers. A fire sprinkler discharges water when the heat of a fire has been detected. A glass bulb sprinkler head will activate when a specific temperature reaches the bulb, causing it to burst.
Fire sprinkler systems are installed in all types of buildings, commercial and residential. They are usually located at ceiling level and are connected to a reliable water source, most commonly city water. A typical sprinkler system operates when heat at the site of a fire causes a glass bulb in the sprinkler head to burst, thereby releasing the water. Only the sprinkler head at the fire location operates - not all the sprinklers on a floor or in a building, (as is common in Hollywood movie scenes). Sprinkler systems help to extinguish and/or reduce the spread of a fire, increasing occupant safety and limiting structural damage. However, significant water damage can occur as a result of the sprinkler system activating. Ask us about various strategies to help reduce this risk.
Our sprinkler system experts can tour your facility and help you decide on the most reliable and cost-effective approach to protect your valuables and keep occupants safe. Our professional and highly skilled inspection, repair and installation teams are available 24 hours a day 365 days a year to ensure your systems are properly installed and maintained for peak performance in the event of fire. Contact us now to schedule your appointment and rest easy by allowing us to design a system or maintenance or testing program to meet your specific needs.
Types of Systems
Wet pipe systems
Wet pipe sprinkler systems are the most common of all types of fire sprinkler systems. They are simple and reliable, with the only two operating components being the automatic sprinklers and the automatic alarm check valve. An automatic water supply provides a constant flow of water under pressure to the system piping, similar to a household faucet. When an automatic sprinkler is exposed for an extended period of time to a specified temperature the heat sensitive element (glass bulb or fusible link) releases, allowing water to flow from that sprinkler.
Dry pipe systems
Dry pipe systems are installed in spaces where the ambient temperature may be cold enough to freeze the water in a wet pipe system, rendering the system inoperable. Dry pipe systems are most often used in unheated buildings, such as; parking garages, outside canopies, or refrigerated coolers. Dry pipe systems are the second most common sprinkler system type.
Operation of Dry Systems - Water is not present in the piping until the system operates. The piping is filled with air above a specially designed value that holds back the water supply. 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. Each sprinkler operates individually. As the air pressure in the piping drops, the pressure differential across the dry pipe valve changes, allowing water to enter the piping system. Water flow from sprinklers, necessary to control the fire, is delayed until the air is vented from the sprinklers. For this reason, dry pipe systems are usually not as effective as wet pipe systems in fire control during the initial stages of the fire.
Water is not present in the piping until the system is activated. Because the sprinkler orifices are open, the piping is at atmospheric pressure. To prevent the water supply pressure from forcing water into the piping, a deluge valve is used in the water supply connection, which is a mechanically latched valve, and stays open once tripped. Because the heat sensing elements present in the automatic sprinklers have been removed, the deluge valve must be opened by a fire alarm system, or a separate dry pipe network use. The type of fire alarm initiating device is selected mainly based on the hazard (e.g., smoke detectors, heat detectors, or optical flame detectors). The initiation device signals the fire alarm panel, which in turn signals the deluge valve to open. Activation can also be manual, depending on the system goals. Manual activation is usually via an electric or pneumatic fire alarm pull station, which signals the fire alarm panel, which in turn signals the deluge valve to open.
Pre-action sprinkler systems are specialized for use in locations where accidental activation is likely and undesired. For example, museums with rare art work, manuscripts, books and data centers which house sensitive information would be best suited for pre-action sprinkler systems. Pre-action systems are hybrids of wet, dry, and deluge systems, depending on the system goal. There are two main sub-types of pre-action systems: single interlock, and double interlock. A pre-action system can be considered a single interlock and double interlock system depending on the system intentions and coverage. A single interlock system operates in a similar manner as the dry pipe system. This type of system has one mandatory events that must occur before water runs into the system; fire detection from a heat or smoke detector where the pre-action valve opens. A double interlock system has two events that must occur; 1) fire detection from a heat or smoke detector and 2) automatic sprinkler operation. Once one of the above occurs, the pre-action valve operates, allowing water to flow into the system piping, essentially turning a dry system into a wet system. These types of systems are regularly used where unintended activation is not desired due to valuable or rare building contents.
Single Interlock Systems
The operation of single interlock systems are similar to dry systems except that these systems require that a “preceding” fire detection event, typically the activation of a heat or smoke detector, takes place prior to the “action” of water introduction into the system’s piping by opening the pre-action valve, which is a mechanically latched valve (i.e., similar to a deluge valve). In this way, the system is essentially converted from a dry system into a wet system. The intent is to reduce the undesirable time delay of water delivery to sprinklers that is inherent in dry systems. Prior to fire detection, if the sprinkler operates, or the piping system develops a leak, loss of air pressure in the piping will activate a trouble alarm. In this case, the pre-action valve will not open due to loss of supervisory pressure, and water will not enter the piping.
Double Interlock Systems
The operation of double interlock systems are similar to deluge systems except that automatic sprinklers are used. These systems require that both a “preceding” fire detection event, typically the activation of a heat or smoke detector, and an automatic sprinkler operation take place prior to the “action” of water introduction into the system’s piping. Activation of either the fire detectors alone, or sprinklers alone, without the concurrent operation of the other, will not allow water to enter the piping. Because water does not enter the piping until a sprinkler operates, double interlock systems are considered as dry systems in terms of water delivery times, and similarly require a larger design area.
Foam water sprinkler systems
A foam water fire sprinkler system is a special application system, discharging a mixture of water and either high or low expansion foam concentrate, resulting in a foam spray from the sprinkler. These systems are usually used with special hazards occupancies associated with high challenge fires, such as flammable liquids storage, and airport hangars. Operation is as described above, depending on the system type into which the foam is injected.
"Water spray" systems are operationally identical to a deluge system, but the piping and discharge nozzle spray patterns are designed to protect a specially configured hazard, usually being three dimensional components or equipment (i.e., as opposed to a deluge system, which is designed to cover the horizontal floor area of a room). The nozzles used may not be listed fire sprinklers, and are usually selected for a specific spray pattern to conform to the three dimensional nature of the hazard (e.g., typical spray patterns being oval, fan, full circle, narrow jet). Examples of hazards protected by water spray systems are electrical transformers containing oil for cooling or turbgenerator bearings. Water spray systems can also be used externally on the surfaces of tanks containing flammable liquids or gases (such as hydrogen). In this case, the water spray is intended to cool the tank and its contents to prevent tank rupture/explosion (BLEVE) and fire spread