Pressure Type Firing Device

Pressure-Release Type Firing Device M3 (Demolition) (Fig 28) has been used to activate antitank mines equipped with supplemen-... 

The primary advantage of using the pressure relief valve is that functioning of this type of device will not release all of the contents of the cylinder, but is designed to reseal after reseating pressure has been achieved. This characteristic, in fire conditions, will minimize feeding the fire in the case of a flammable lading. 

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. 

The State Police report quoted a refrigeration serviceman who reported that all of the valves on the evaporator were shutoff and the fire chief found a steam hose steaming underneath the machine. The serviceman had previously seen steam used to melt ice buildup around the valves and to heat the oil in the machine to make it easier to drain the oil. [ 51 The District Engineering Inspector s report confirmed that the machine was completely isolated and the ammonia system was not protected by a safety valve or any type of pressure-relief device. The cause of the accident was the presence of the steam ho.se underneath the equipment to melt the ice on the drain valve or to help evacuate the system. The inspector s report could not determine if these preparations were intentional or accidental. 151... 

Fire Extinguishers. Are devices containing one of more non-flammable gases under pressure. They have a mechanism to spray the contained gas, or expel a liquid or powder through some type of nozzle. lATA App. A... 

A combiuatiou of water discharge devices (sprinklers), distribution piping to supply water to the discharge devices or more sources of water under pressure, water flow controlling devices (valves), and actuating devices (temperature, rate of rise, smoke, or other type device). The system automatically delivers and discharges water in the fire area. 

The real world test parameters discussed above have been incorporated into the fire hazard assessment model used by UL (Webber 1983) to determine the compliance of transformer fluids with section 450.23 of the National Electrical Code. In order to be compliant with the code, transformers insulated with less-flammable liquids are permitted to be installed without a vault in Type I and Type II buildings of approved noncombustible materials in areas in which no combustible materials are stored, provided there is a liquid confinement area, the liquid has a fire point of not less than 300 C and the installation complies with all restrictions provided for in the listing of the liquid. UL has identified the need for pressure relief devices and current limiting fusing to limit the effect of possible high current arcing faults. 

Type CG-9. This is a high-pressure fusible plug for use at cylinder service pressures above 500 psig (3450 kPa) using a fusible alloy with a yield temperature not over 224°F (107°C). The nominal yield temperature is 217°F (103°C). (See Fig. 8-13.) Because of its high resistance to fusible metal extrusion, the device has been used extensively on vehicular compressed natural gas fuel cylinders where it provides protection of partially charged cylinders in fires. 

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