Sprinkler heads

Fire-detection devices such as flame-sensing or ioni2ation-interference types operate much more rapidly than sprinkler heads and are used extensively both as alarms and to activate fixed fire-extinguishing systems. 

Question 15.3 How Does an Automatic Fire Sprinkler Head Operate ... 

Each sprinkler head on an athletic field sprays water at an average of 16 gallons per minute. If 5 sprinkler heads are flowing at the same time, how many gallons of water will be released in 10 minutes ... 

Sprinkler systems are an effective way to contain fires. The system consists of an array of sprinkler heads connected to a water supply. The heads are mounted in a high location (usually near ceilings) and disperse a fine spray of water over an area when activated. The heads are activated by a variety of methods. A common approach activates the heads individually by the melting of a fusible link holding a plug in the head assembly. Once activated, the sprinklers cannot be turned off unless the main water supply is stopped. This approach is called a wet pipe system. These systems are used for storage areas, laboratories, control rooms, and small pilot areas. Another approach activates the entire sprinkler array from a common control point. The control point is connected to an array of heat and/or smoke detectors that start the sprinklers when an abnormal condition is detected. If a fire is detected, the entire sprinkler array within an area... 

Determine the fire water requirements (gpm, number of sprinkler heads, and pump horsepower) to protect an inside process area of2000 ft2. Assume that the sprinkler nozzles have a 0.5-in orifice and that the nozzle pressure is 75 psig. 

Determine the sprinkler requirements for a chemical process area 150 ft by 150 ft. Determine the number of sprinkler heads and the pump specifications for this system (HP and gpm). Assume that the friction loss from the last sprinkler head to the pump is 50 psi and that the nozzles (0.5-in orifice) are at 75 psig. 

Alarm Activation - all systems should be fitted with alarms that will indicate if water flow has occurred. The alarm activation should occur with the activation of one sprinkler head and usually simulated by the fitting of an orifice at the inspectors test outlet. 

Eusible plugs or sprinkler heads with Ionization UV... 

The most widely used heat detector is the automatic sprinkler head. 

The most common and least complicated of all sprinkler systems is the wet pipe system, where all the pipes are normally full of water. When the fusible link fails in one or more sprinkler heads, water is immediately discharged through those... 

The principal difference between a pre-action system and a standard dry pipe system is that in the pre-action system, the water supply valve is actuated independently of the opening of the sprinklers. The water supply valve is opened by the operation of an automatic fire detection system, which immediately allows water to enter the overhead piping. Then, when the fire generates enough heat to fuse the sprinkler head, water is immediately discharged on the fire as with a wet pipe system. This system reduces the inherent time lag of a dry pipe system, but can still be used in unheated areas. An example of a pre-action system is shown in Figure 7-26. 

Any suitable fire detection system can be utilized to actuate the control valve. Since any other fire detection device is likely to operate faster than a sprinkler head, it is common for waterto have reached the sprinkler by the time... 

System integrity can be monitored (it is required when more than 20 sprinkler heads are involved) by providing low air pressure, approximately 5 psi (34.5 kPa), in the piping. A common mistake is made by using high pressure air, which results in delayed delivery of water. 

A deluge sprinkler system is a sprinkler system designed to NFPA 13 with open sprinkler heads. A water spray system is hydraulically designed with open spray heads to protect a specific hazard. Water spray systems are discussed in Section 7.4.8. 

Small wet pipe systems can be protected by an antifreeze solution. The extent of the system should be limited to 20 sprinkler heads or less. For systems over 20 sprinkler heads, a dry pipe system should be used. 

Sprinkler heads that are exposed to potential mechanical damage should be protected with guards. 

Deluge protection can be applied over the entire hazard area with open sprinkler heads located at various floor levels or fixed water spray systems can be applied specifically on the equipment to be protected. Specific water spray application is preferred because it provides better equipment cooling and reduces the water wasted due to wind and fire draft. 

Fire detectors—dry-pilot head and pneumatic rate-of-rise heat detectors are the most frequent devices used. A dry pilot head detection systems uses 165°F (74°C) V2-in sprinkler head with air pressure maintained in the piping. When the sprinkler opens the air is released resulting in the sprinkler valve opening. Other types of detectors include ultraviolet, infrared flame detectors, or thermostatic cable heat detection. 

With the exception of high expansion foams, all other foams can be used in foam-water sprinkler system. However, AFFF is the most versatile agent because of its spreading capability and it can be applied through ordinary sprinkler heads. 

Fusible link A connecting link device that fuses or melts when exposed to heat. Used in sprinkler heads, fire doors, and ventilators. 

PEA Professional Enviromnental Auditor, a designation devised and trademarked by the author. Pendent sprinkler An automatic sprinkler head designed for placement and operation with the head pointing downward from the piping. 

Pre-action System A type of automatic sprinkler system in which thennostatic devices are employed to charge the system with water before individual sprinkler heads are fused. 

Sterilizers/ovens are unloaded and items staged prior to transfer to the individual fill rooms. ISO 5 air is provided over the discharge area of ovens (and autoclaves if items are sterilized unwrapped) to provide protection until the items are ready for transfer. The heat loads in this room may be such that special high-temperature sprinkler heads may be necessary to avoid unintentional discharge when unloading hot materials. This room may not be separate from the corridor used to connect the fill rooms. It is ordinarily adjacent to any aseptic storage area. 

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