Active sprinkler systems

In addition, the copper industry s market development activities have resulted in appHcations such as clad ship hulls, sheathing for offshore platforms, automotive electrical systems including electric vehicles, improved automobde radiators, solar energy, fire sprinkler systems, parts for fusion reactors, semiconductor lead frames, shape memory alloys, and superconducting ceramics (qv) containing copper oxides. 

Design ventilation system to keep flammable concentration below lower flammable limit Provide on-line flammable gas detection and activation of inerting system Install automatic sprinkler system Install deflagration vents... 

Arsenic and antimony are metalloids. They have been known in the pure state since ancient times because they are easily obtained from their ores (Fig. 15.3). In the elemental state, they are used primarily in the semiconductor industry and in the lead alloys used as electrodes in storage batteries. Gallium arsenide is used in lasers, including the lasers used in CD players. Metallic bismuth, with its large, weakly bonded atoms, has a low melting point and is used in alloys that serve as fire detectors in sprinkler systems the alloy melts when a fire breaks out nearby, and the sprinkler system is activated. Like ice, solid bismuth is less dense than the liquid. As a result, molten bismuth does not shrink when it solidifies in molds, and so it is used to make low-temperature castings. 

Many office buildings rely on ceiling sprinkler systems as effective means of extinguishing a fire. How are these systems activated The heat generated by a fire is the key to the operation of such water sprinklers. 

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... 

Sprinkler systems can cause considerable water damage when activated, depending on the contents of the building or process structure. Statistically, the amount of water damage is never as great as the damage from fires in areas that should have had sprinklers. 

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. 

If a sprinkler system is installed in a computer room or similar area, provisions must be made to automatically de-energize all electrical power to the room and equipment, except power to lighting, in the event of sprinkler operation. Ensure that de-energizing activity leads to a fail-safe condition. Preferably, this should take place prior to water application to minimize damage to exposed electronic circuits. This can be accomplished automatically by smoke detection systems. Manual activation is tolerable for constantly attended locations. Where automatic sprinklers are installed in areas containing minimal combustibles as described above, a sprinkler density of 0.10 gpm/ft (0.38 Ipm/m ) should be provided. Refer to NPEA 75. 

Active fire protection of cooling towers is primarily provided by sprinkler systems. 

Black smoke and fire from the heater stack were reported by a chemical process operator making his round at about 9 45 A.M. Nearby sprinkler systems activated, and the emergency squad was summoned. The emergency squad set up fire hose streams and began cooling down the heater structure. Within 15 minutes all external flames from the heater ceased, but black smoke continued to pour from the heater stack. A few minutes later the fire flared up through the stack for about five minutes more. 

Class 1 safety instrumentation loops include alarms and trips on storage tanks containing flammable or toxic liquids, devices to control high temperature and high pressure on exothermic-reaction vessels, and control mechanisms for low-flow, high-temperature fluids on fired heaters. Other Class 1 instruments include alarms that warn of flame failure on fired heaters, and vapor detectors for emergency valve isolation and sprinkler-system activation. All of these alarms, shutdown valves, and other critical instruments are regularly proof-tested to a well-defined schedule. 

Tests conducted with the propellant build-up configuration in the ignition end of the conveyor resulted in more erratic and aggressive burning reactions than observed in Stage one tests. Approximately 60 pounds of MISP was used for each test. For these tests, aluminum rupture discs 0.0008-inch thick were used on each pressure relief vent. One IR detector activating the sprinkler system was located in No. 1 (see Figure 4) position. 

Sprinkler systems and water stand pipes were purposely omitted in the Chemistry wing to avoid accidental contact of water with active metals or metal hydrides. Cylinders supplying specialty gases or compressed air to laboratories are stored in the central hall in locked chambers located between the utility chases and identical to them in outward appearance. 

In February of 1988, however, Chu—and researchers working on their own at the National Institute for Metals at Japan s City of Brains, at Tsukuba—came up with something that finally seemed legitimate. The compounds used by the two groups were very similar, mixtures of bismuth—a crystalline metal used to make alloys, heat-activated safety devices for fire detection and sprinkler systems, and medical and cosmetic preparations—strontium, calcium, copper, and oxygen (Chu s also contained aluminum). The Japanese ceramic had zero resistance at 105° K, Chu s at 114° K. 

Active for example, safety shutdown systems to prevent accidents (e.g., a high level alarm in a tank shuts automatic feed valves) or to mitigate the effects of accidents (e.g., a sprinkler system to extinguish a fire in a building). Active systems require detection of a hazardous condition and some kind of action to prevent or mitigate the accident. Multiple active elements involve typically a sensor (detect hazardous condition), a logic device (decide what to do) and a control element (implement action). 

A wide variety of sensing and initiating devices are available that can detect heat, smoke, radiant energy, and fire gas products. These devices should be selected based upon the type of fire anticipated. Additionally, sprinkler system water flow, activation of other extinguishing systems, and manual fire alarm pull stations can also be used to initiate an alarm signal. 

In addition to fire extinguishers, a sprinkler system in the ceiling is almost always available. These are, of course, useful in extinguishing Class A fires. However, these sprinklers activate automatically, in response to the presence of smoke and/or debris in the laboratory air. The automatic addition of water to a class B, C or D fire would be counter-productive and should be avoided. Therefore, the fire-producing potential of material in each room should be evaluated, prior to installation of the sprinkler system. 

Failure of Copper Pipe in a Sprinkler System Straight sections and T-sections were examined along with the analysis of water for corrosion products for microbiological activity. The straight sections of the pipe showed dark red and greenish spots on the surface (Fig. 5.48) through-wall pits were present in the red spots. The T-sections did not have red spots (Fig. 5.49), but one sample had a crack (Fig. 5.50). 

Deluge systems—are similar to very large sprinkler systems and are used to extinguish fires and suppress toxic releases. Deluge systems are expensive and are used primarily on processes concerned with extremely hazardous chemicals, such hydrofluoric acid. Most are activated automatically. 

Does the operator have time to activate emergency systems such as manual sprinkler systems and fire water monitors ... 

---