Relief pressure venting

The reaction vessel is provided with a pressure relief venting system which includes a small spring-loaded relief valve the design also permits the lifting of the entire cover if necessary. 

Fig. 4.28 Schematic cross-section of the upper part of the Energiser L 91 spiral wound Li-FeSn cylindrical cell, showing the positive temperature coefficient (FTC) resettable safety switch, and the pressure relief vent, (By permission of Eveready.)...

Two lypes of batteries having immobilized electrolyte systems are also made. They are most common in consumer applications, but their use in industrial and SLI applications is increasing. Both types have low maintenance requirements and usually can be operated in any position. They arc sometimes called valve regulated or recombinant batteries because they are equipped with a one-way pressure relief vent and normally operate in a sealed condition with an oxygen recombination cycle to reduce water loss. 

Equipment and process design avoided process conditions which could result in an explosive reaction by preventing unnecessary and potentially explosive accumulations of in-process and finished materials and offering minimum confinement to the propellant by incorporating pressure relief venting. 

Figure 5. Simulated CASBL conveyor. (V) Locations of 6 in ID conveyor pressure relief vents (when used) (S) locations of sprinkler nozzle fittings welded to top of conveyor.

Tests conducted with the propellant build-up configuration in the ignition end of the conveyor resulted in more erratic and aggressive burning reactions than observed in Stage one tests. Approximately 60 pounds of MISP was used for each test. For these tests, aluminum rupture discs 0.0008-inch thick were used on each pressure relief vent. One IR detector activating the sprinkler system was located in No. 1 (see Figure 4) position. 

Pressure relief/vent collection Release devices (flares, scrubbers, etc.) Plant equipment isolation Critical alarms/interlocks Fire detection/protection Gas detection Flame arrestors Emergency system ser ices Appropriate grounding and bonding... 

Laminar flow burners of the type shown in Figure 28-11 provide a relatively quiet flame and a long path length. These properties tend to enhance sensitivity for atomic absorption and reproducibility. The mixing chamber in this type of burner contains a potentially explosive mixture, which can be ignited by flashback if the flow rates are not sufficient. Note that the burner in Figure 28-11 is equipped with pressure relief vents for this reason. 

Provide safety and alarm devices, such as fire-alarm systems, combustible-vapor detectors, flame arresters, pressure-relief venting of equipment, flame-failure controls for oil- and gas-fired equipment. 

CALCULATION OF REQUIRED VENT AREA The methods available for calculating the cross-sectional area of an emergency pressure relief vent have been reviewed in References 93 and 95. The most recent procedures and the ones recommended for general use come from DEERS, a multi-company research programme -. ... 

Instructions for the erection and operation of electrostatic precipitators are moreover given in VDE0146 and 0105 (Part8). With regard to the prevention of dust explosions and fire outbreaks and to pressure relief (venting) arrangements for dust explosions VDI 2263 and 3673 should be consulted. 

Good storage practice for hazardous materials includes segregation or separation from other materials. Separate detached structures, isolated fire compartments, and separation by inert or nonhazardous materials are recommended, depending on the degree of hazard. Other points to check are ttie need for pressure relief vents for containers and explosion venting for ttie storage area, which should be a separate structure. 

The construction of the spiral-wound cylindrical battery is shown in Fig. 14.78. These batteries typically have several safety devices incorporated in their design to provide protection against such abusive conditions as short circuit, charging, forced discharge, and over heating. Two safety devices are shown in the figure—a pressure relief vent and a resettable thermal switch, called a positive thermal coefficient (PTC) device. The safety relief vent is designed to release excessive internal pressure to prevent violent rupture if the battery is heated or abused electrically. 

T re are other PRD, such as pressure and vacuum vents and emergency pressure relief vents for storage tanks, and safety instrumented system (SIS). They are not discussed in this chapter. 

Eveready cylindrical cells are protected against cell rupture (caused by gassing generated during polarity reversal) by a pressure-relief vent. 

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