Isolation of fuel

The time required to provide isolation of fuel that may be released. 

Isolation of fuel from the oxidizer can be accomplished in several ways. If the fire is fed by fuel from a ruptured line, an upstream valve can be closed. This isolates the source of fuel. Blanketing with an inert gas or foam isolates the fuel from air. 

The typical stack construction for PEM (and other) fuel cells is a series-connection of cells with bipolar plates interposed between adjacent cells (or membrane-electrode assemblies). The bipolar plate must provide for electronic conduction from one cell to the next isolation of fuel on one side from oxidant (air) on the other side and distribution of fuel and air reactants to the respective adjacent anode and cathode. In an edge-cooled stack of the type described above, the bipolar plate also contributes to heat rejection by conducting heat laterally to its tinned edges, where forced-air convection is employed. 

Efforts are made in the construction of new, large tank farms to achieve electrical isolation of buried and cathodically protected fuel installations from all... 

A furnace was protected by a relief valve on its inlet line (Figure 10-1). A restriction developed after the furnace. The relief valve lifted and took most of the flow. The flow through the furnace tubes fell to such a low level that they overheated and burst. The low-flow trip, which should have isolated the fuel supply to the furnace when the flow fell to a low value, could not do so because the flow through it was normal. 

The furnace was fitted with interlocks that should have isolated the fuel supply if the tube wall temperature or the pressure of the heat transfer oil got too high. Neither interlock worked, and neither had been tested or maintained. The set-point of the high tube wall interlock had been raised far above its original set-point, from 433°C to 870°C, a simple way of putting it out of action [15]. Changing the set-point of an interlock is a modification and should be allowed only when the equipment is capable of withstanding the new conditions (see Chapter 2). 

Carbon monoxide is widely used as a fuel in the form of producer gas or water gas and is also formed during the isolation of many metals from their oxides by reduction with coke. Producer gas is obtained by blowing air through incandescent coke and consists of about 25% CO, 4% CO and 70% N2, together with traces of Hi, CHj and O2. The reactions occurring during production are ... 

The isolation of mercury is comparatively straightforward. The most primitive method consisted simply of heating cinnabar in a fire of brushwood. The latter acted as fuel and condenser, and metallic mercury collected in the ashes. Modem techniques are of course less crude than this but the basic principle is much the same. After being crushed and concentrated by... 

T. Flynn, ML. Ghirardi, M. Seibert (1999) Isolation of Chlamydomonas mutants with improved oxygen-tolerance. In Division of Fuel Chemistry Preprints of Symposia, 218th ACS National Meeting, 44 846-850... 

Operational personnel should be expected to suppress only very small incipient fires. All other emergencies are to be handled with ESD/blowdown, isolation, fire protection systems (active or passive) or exhaustion of fuel sources by the incident. 

If the fuel is removed or consumed by the subject combustion process, no more fuel supplies will be available for the combustion process to continue and it will cease. In some cases, a fuel is not literally removed from a fire, but is separated from the oxidization agent. Foam suppression methods are good examples where the a barrier is introduced to remove the fuel from the air (i.e., oxidizer). Storage tanks and pipeline fires can use pump-out methods and inventory isolation, respectively, as methods of fuel removal. 

For ESD isolation valves (i.e., EIVs) a fail safe mode is normally defined as fail closed in order to prevent the continued flow of fuel to the incident. Blowdown or depressurization valves would be specified as fail open to allow inventories to be disposed of during an incident. Special circumstances may require the use of a foil steady valve for operational or performance reasons. These applications are usually at isolation valves at components, i.e., individual vessels, pumps, etc., where a backup EIV is provided at the battery limits that is specified as fail closed. The fail safe mode can be defined by the action that is taken when the ESD system is activated. Since the function of the ESD system is to place the facility in its safest mode, by definition the ESD activation mode is the foil safe mode. 

Process fires will continue and may escalate until the flow of fuel is stopped, the fuel is fully consumed, or the fire is extinguished. Isolation valves are used to reduce or isolate inventories of flammable gases or liquids. 

Thietanes and 3-thietanones represent the only four-membered sulfur-containing heterocycles of the title group that have been isolated from natural sources. Even in petroleum deposits, where 5- and 6-membered cyclic sulfur compounds are common, thietanes occur only in small amounts. However, thiacyclobutane (1) and thiacyclopentane are both commonly found in shale oil and could be utilized as a possible source of fuel. ... 

The sonophotocatalytic taction system is a novel idea for overall liquid water splitting. The H2 obtained, nowever, was mixec with other products such as 02 in the reactor When H2 is utilized in practice, e.g., in fuel or chemical synthesis, etc., it is desirable to isolate H2 from the product. Namely, isolation of H2 is required. Although separation of H2 from other products may be possible using a membrane, the method is likely to skip this process, and it is desirable to avoid the use of additional equipment as much as possible. 

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