Water deluge systems

Deluge systems should generally be activated by automatic means. Activation by manual means defeats the objective of installing a deluge system, and fire water monitors should be provided instead as they are more cost effective where manual means is relied upon. Most systems provided at petroleum facilities are typically activated by a heat detection. Usually a fusible plug pneumatic loop detection system or UV/IR detectors are placed around the equipment. This insures activation when operators are not present and only when a real fire situation is present. 

For vessels protected by deluge systems the most important points are the vessel ends, the portion of the vessel that contains a vapor space (i.e., the unwetted portion), flange connections that can leak and if the vessel is located close to the ground without good surface drainage, the immediate underneath surface of the vessel that would exposed to the flames. 

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The use of appropriate instruments to monitor equipment operation and relevant process variables will detect, and provide warning of, undesirable excursions. Otherwise tliese can result in equipment failure or escape of chemicals, e.g. due to atmospheric venting, leakage or spillage. Instruments may facilitate automatic control, emergency action such as coolant or pressure relief or emergency shutdown, or the operation of water deluge systems. 

To protect against structural failure, water-deluge systems are usually installed to keep vessels and structural steelwork cool in a fire. 

The process area has combustible gas detectors, fireproofing, and a water deluge system. Cable trays are protected with deluge, and portable dry chemical extinguishers are in the process area. Diesel-powered fire water pumps can provide a maximum fire water demand for 4 hr. 

Loss control features include combustible gas detectors installed around the containment area and transfer system. A diesel-driven fire pump is capable of handling the emergency demand for 4 hr. A water deluge system has been installed around the storage tank and transfer pump. 

The Detonator Module is a control unit that is used with the UV and/or IR detection system to activate the water deluge system. 

For only if the detection system and water deluge system work together to perform their functions in the shortest length of time will consistently reliable protection be possible. 

Research on water explosion inhibiting systems is providing an avenue of future protection possibilities against vapor cloud explosions. British Gas experimentation on the mitigation of explosions by water sprays, shows that flame speeds of an explosion may be reduced by this method. The British Gas research indicates that small droplet spray systems can act to reduce the rate of flame speed acceleration and therefore the consequential damage that could be produced. Normal water deluge systems appear to produce too large a droplet size to be effective in explosion flame speed retardation and may increase the air turbulence in the areas. 

Foam-water deluge systems are especially applicable to the extinguishment, prevention and control of most flammable liquid hazards. They may be used for any, or a combination, of the following purposes. 

The fire erupted late in the day shift. The incoming evening emergency squad quickly responded and assisted the day shift crew in supplying about 6,000 gpm (380 L/s) of fire hose coverage in addition to fixed fire-water deluge systems. The fire was out in about 25 minutes. 

Water Deluge System Application In Munition Plants... 

Still another consideration is fires occurring in machine equipment such as electrical fires or lubricating oil fires in a fuze assembly machine. Here, primary consideration is the rapid detonation of the fire and deactivation of the equipment to prevent the continous machine operation which would cause the fire to intensify or propagate into a detonation. Fire fighting in this case, in the form of a water deluge system is the secondary action to extinguish the cause of the fire. 

Automatic water deluge systems with fast acting sensors and valves. 

In areas where the possibility of fire is the greatest, a high speed ultraviolet detection system is employed. The ultraviolet eyes detect the presence of a flame and are interconnected with a high speed water deluge system. In some areas the fire detection devices have process shutdown capabilities. The detectors are situated such that the entire hazardous area can be monitored at all times. They are equipped with air shields that not only cool the detector but also blow clean air across the face of the lens, keeping any dust from accumulating on the lens, which assures detection capability. Further, the detectors have a built-in test lamp which serves as a check of... 

Figure 6-1 Excellent response by the emergency squad to reinforce the fixed fire-water deluge system.

Within 20 to 35 minutes after the heater was fired, a fire-water sprinkler system tripped. A heater flame failure alarm occurred a short time later. Witnesses stated flames were over 50-ft. (15 m) high in approximately five seconds after the tube ruptured. The fire damages were the greatest on the third and fourth levels of the process unit as 10- to 12-mph winds carried flames and destructive heat into the unit. There was an excellent response by the emergency squad with eight hose lines reinforcing the fixed fire-water deluge systems. 

To protect against structural failure, water-deluge systems are usually installed to keep vessels and structural steelwork cool in a fire. Water mist fire protection systems are described in NFPA 750 (2006) and API PUBL 2030 (1998). 

Approaches to blast protection can be categorised as active (deployed upon detection of an explosion) or passive (always present). An example of an active mitigation system is the water deluge system used on offshore oil and gas platforms [9]. Upon detection of a gas leak, the entire area is showered with carefiilly sized water droplets in order to prevent ignition and remove the energy from a vapour cloud explosion. An active system can only work if the imminent explosion can be detected and a suitable system deployed in time. These systems work offshore because the gas leak, which accumulates relatively slowly, can be detected easily and the water system deployed. A number of researchers have worked on the detection and deployment of mitigation devices for explosive detonations with military applications [10,11]. Such systems have yet to be deployed in the military, and (at the time of writing) no such detection systems are available for the case of explosive detonation on board an aircraft. For such a system to be viable, it would need to be robust and inexpensive to install and operate. 

Explosives disposal Water deluge system provision of safe areas for nonparticipants decontamination system on-site medical facilities evacuation plan event rehearsal. 

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