Fusible link

Eliminate sources of fuel Blank unused lines at switching station Provide emergency cooling activated by external fire (e.g., fusible link, plastic tubing)... 

Use fusible link fire safe valves for automatic closure under fire conditions... 

Smoke damper A damper installed in a ductwork system designed to close in case of fite by means of a fusible link and electrical or magnetic device to stop the spread of smoke. 

Unlike oil burners, there is no requirement to install a fire valve. With oil burners, this is usually met by having a fusible link sited over the burner and connected in a tensioned wire, which holds open a weighted valve in the oil supply so that the valve closes if the link melts. 

However, if it is desired to protect a self-contained area such as a boiler house against fire the best method is to use suitably located fusible links as interlocks in the controls of the burners, designed to BS 5885. The burner valves should be to BS 5963 and mounted in a non-vulnerable position. 

Most ventilators are powered in one direction with spring return. Thus, a pneumatic ventilator might be described as pressure to open or pressure to close. With the pressure to open type the ventilator will fail to the closed position under the influence of the return spring, ensuring the building remains weatherproof. Where ventilators are installed mainly as smoke ventilators it is important that they fail to the open position, so pressure to close ventilators should be used. A fusible link is normally fitted into the controls so that in the event of fire, affected ventilators will open automatically to release smoke and heat. 

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... 

Fire dampers are an assembly of louvers that are arranged to close to prevent the passage of flame and heat. Dampers are installed in ventilation openings or shafts to provide a fire rated barrier equal to the surrounding barrier. They are activated by spring release by the melting of a fusible link, or by remote control signals. 

Acceptance testing of fusible link fire dampers should always include a random sample actual fusible link (melting) test of the installed assembly that causes the damper to close. Many times an improperly installed damper will not close correctly and the shutter louvers become hung up or twisted. An alternative sometimes available is a link assembly that can be temporary installed that is easily cut by a pair of clippers. The fusible link melting temperature can then be tested separately at a convenient location without subjecting the installation heat or flames for testing purposes. 

Wet or dry chemical fixed suppression systems are typically provided over the kitchen cooking appliances and in exhaust plenums and ducts. Activation means is afforded by fusible links located in the exhaust ducts/plenums usually rated at 232°C (450°F). Manual activation means should not be provided near the cooking area, but in the exit routes from the facility. The facility fire alarm should sound upon activation of the fixed suppression system and power or gas to the cooking appliances should be automatically shut off. The ventilation system should also be shut down by the activation of the fire alarm system. Protective caps should be provided on the suppression nozzles to prevent plugging from grease or cooking particulates. 

Fusible Link - A release device activated by the heat effects of a fire. It usually consists of two pieces of metal joined by a low melting point solder. Fusible links are manufactured at various temperature ratings and are subject to varying normal maximum tension. When installed and the fixed temperature is reached, the solder melts and the two metal parts separate, initiating desired actions. 

Local automatic—some isolation valves may be automatic, but locally actuated. In this case, the actuation device may be a fusible-link or fusible-tubing arrangement. 

These are fixed temperature devices that operate when the fusible link or ele-... 

The most common and least complicated of all sprinkler systems is the wet pipe system, where all the pipes are normally full of water. When the fusible link fails in one or more sprinkler heads, water is immediately discharged through those... 

Where unloading of flammable liquids must be done from the bottom of the tank car or tank truck, a remote actuated unloading valve equipped with a fusible link for detecting high temperature should be provided. 

Fusible link A connecting link device that fuses or melts when exposed to heat. Used in sprinkler heads, fire doors, and ventilators. 

There are two types of thermal sensors the rate-of-rise sensor and the absolute temperature sensor. Fixed temperature sensors are usually either bimetallic or low-melting-point fusible link devices that activate sprinklers or other extinguishing devices. 

The fire protection system consists not only of a deluge system activated by the ultraviolet sensors, but also of fusible link type fire systems. The deluge system has a trip mechanism from mercury checks activated by heat-activated-devices, a manual release on the deluge valve, a pneumatic remote trip station, and an electrical push button along with the electrical trip mechanism from the U/V detectors. The remote trip stations are located by escape routes so it is possible for the operator to trip the systems as he exits the building without exposing himself to further danger. 

Any areas which have flammable liquids are equipped with a foam fire fighting system. The foam system is activated by fusible links or manually. The fire truck has a foam eductor system which can be used to extinguish flammable liquid, or Class II fires. The foam is educted out of five gallon buckets and mixed with the water stream in the eductor. 

Numetal (386°C), Permanorm 5 (459°C), Trafoperm (754°C). The method does not permit the temperature measurement with high precision. These standards have been studied by several authors. The ICTA temperatures are within 5-10°C. McGhie et al. proposed a calibration technique in which a small inert platinum weight is suspended by a fusible link composed of a calibration standard that releases the platinum weight at the temperature of melting. The Mettler instrument TGA 850 is constructed so that the melting curve of standards can be measured and used as calibration, as demonstrated in Table 4. 

Ordinary protective fuses of the screw-in type can be made to serve as an efficient initiator for black powder. I hc end window of the fuse is first removed, exposing the fusible link. The altered fuse is then wired directly a-cross a circuit into which 115 volt alternating current can be introduced. Black powder is piled on the fuse, making certain that some gets in direct contact with the interior link. When the circuit is closed, the fuse forms a short circuit to the current path, hc fu.sibic link then ruptures with a flash quite sufficient to ignite the powder. 

Fusible links (Zener zap, metal bridge blowing, polyresistor zap). 

A trimmable resistor network in the feedback loop of the operational amplifier OP2 is aligned during the calibration process. The total resistance of the resistor network is increased by opening fusible links (Fig. 6.2.11). A test calibration is not possible. At the end of the hole trimming a special link is fused to deactivate the complete control logic for safety reasons. Consequently, accidental trimming is prevented. 

McGhie et al. (53, 54) proposed a new temperature calibration technique in which a small inert platinum weighl is suspended within the thermo-balan ce sample container by a fusible link composed of a temperature calibration material. When the temperature exceeds the fusible link melting point, the platinum weight is released. The weight is either caught in the sample container, producing an action/reaction response on the TG curve,... 

Figure 3.)3. Fusible link temperature calibration. Modification of sample container (54).

Figure 3.14. Typical fusible link weight-drop curve (54).

Table 3.1. Fusible Link Temperature Calibration Data. Dropping Weight Method (53)...

Loss of capability to energize the fusible links to dump the reserve shutdown control (RSC) material... 

---