Pressure-Release Type Firing Device

A similar device, the Ram-Jet Engine Igniter M132 (T123) (90 sec) (formerly FLARE, Igniting M132), is described on pp 122-23, 

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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. 

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