Activators electric igniters

Then the tap is closed and the strand ignited at the top. When flame reaches the upper "timing lead it breaks the fuse wire. This activates electrical relay causing a timing device to start. When the flame reaches the lower wire the relay would stop the timing device. Thus a measurement can be taken for the burning to travel betw the accurately known distance along the strand. This method... 

Timely ignition is critical, so there is a need for immediate or continual activation of the system being used. Devices that can be used for remote ignition include flare pistols, electric ignition devices, and propane burners. The location and spacing of the devices are typically functions of the material and facility however, it is critical that a release does not go undetected by the gas detectors (if there is no continual ignition source) or by the ignition system itself. 

Air bags are activated when a severe impact causes a steel ball to compress a spring and electrically ignite a detonator cap. This action causes sodium azide (NaN3) to decompose explosively according to the following reaction ... 

Thermal batteries are activated by applying an external signal to an initiation device that is incorporated in the battery. There are four generally used methods of activation electric signal to an electric igniter mechanical impulse to a percussion primer mechanical shock to an inertial activator and optical energy (laser) signal to a pyrotechnic material. 

The heat peUet used for activation in these batteries is usually a mixture of a reactive metal such as iron or zirconium [7440-67-7] and an oxidant such as potassium perchlorate [7778-74-7]. An electrical or mechanical signal ignites a primer which then ignites the heat peUet which melts the electrolyte. Sufficient heat is given off by the high current to sustain the necessary temperature during the lifetime of the appHcation. Many millions of these batteries have been manufactured for military ordnance as they have been employed in rockets, bombs, missiles, etc. 

Combustible gas detection systems are frequently used in areas of poor ventilation. By the early detection of combustible gas releases before ignitible concentration levels occur, corrective procedures such as shutting down equipment, deactivating electrical circuits and activating ventilation fans can be implemented prior to fire or explosion. Combustible gas detectors are also used to substantiate adequate ventilation. Most combustible gas detection systems, although responsive to a wide range of combustible gases and vapors, are normally calibrated specifically to indicate concentrations of methane since most natural gas is comprised primarily of methane. 

Tanks containing liquefied gases that are kept liquid by refrigeration sometimes have electric heaters beneath their bases to prevent freezing of the ground. When such a heater on a liquefied propylene tank failed, the tank became distorted and leaked—but fortunately, the leak did not ignite. Failure of the heater should activate an alarm. As stated in Section 5.2, frequent complete emptying of a tank can weaken the base/wall weld. 

Ignition prevention by an automatic disconnection of the battery in case of an accident, separation of fuel supply lines and electrical systems, and design of proper systems for both active and passive ventilation, such as openings to allow hydrogen to escape upward. 

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