Vent-directing devices

Reactors or storage vessels are fitted with an overpressure protection vent directly to roof level. Such devices (e.g. relief valves) protect only... 

Downstream of the vacuum train, the waste gas vents directly to the atmosphere through the discharge separator/silencer. The purpose of this device is to separate any excess seal water which then passes to a drain, and to quiet the waste gas stream while venting to the atmosphere. 

Laboratory ovens should be constructed such that their heating elements and their temperature controls are physically separated from their interior atmospheres. Small household ovens and similar heating devices usually do not meet these requirements and, consequently, should not be used in laboratories. With the exception of vacuum drying ovens, laboratory ovens rarely have a provision for preventing the discharge of the substances volatilized in them into the laboratory atmosphere. Thus, it should be assumed that these substances will escape into the laboratory atmosphere and may also be present in concentrations sufficient to form explosive mixtures with the air inside the oven (see Chapter 5, section 5.G). This hazard can be reduced by connecting the oven vent directly to an exhaust system. 

Ensure that pressure-relief devices vent directly to an exhaust system. 

Early BWRs used an isolation condenser, although such is not specific to the direct cycle. This device removes decay heat by steam flow through a heat exchanger the other side of which is water vented to the atmosphere. Discuss the relative merits of such a boiler. 

High Velocity Vent Valve A device to prevent the passage of flame in the reverse direction, consisting of a mechanical valve which adjnsts the opening available for flow in accordance with the pressnre at the inlet of the valve in snch a way that the efflnx (exiting) velocity cannot be less than 30 m/s. 

API (Venting Atmospheric and Low-Pressure Storage Tanks, Standard 2000, Washington, 1998) provides guidance for vacuum protection of low-pressure storage tanks. Where vacuum relief devices are provided, they should communicate directly with the vapor space in the vessel and should be installed so that they cannot be sealed off by the liquid contents in the vessel. Valves should be avoided in the inlets or outlets of vacuum relief devices unless the valves are reliably car-sealed or locked open, or excess relief capacity is provided (e.g., via multiple-way valves). 

A restriction to the operation of GC-MS can be caused by solvent peaks. If the solvent injected onto a packed column flows via a separator into the ion source of the mass spectrometer, it results in an unacceptable increase in pressure which causes the built-in pressure protection devices to shut the mass spectrometer down. It also much reduces the lifetime of source components such as filaments and heaters. Therefore a valve is fitted at the end of the column, which allows effluent to be vented to a pump or to tile atmosphere until the solvent has passed. The flow rates associated with the use of capillary coliunns are such that the pressure generated by the solvent is not as great as with a packed column. The total effluent may therefore be passed directly into... 

Because there are no reasonable methods for mitigating risk following the occurrence of a BLEVE, all practical measures should be taken to prevent the causes of a BLEVE. This could include fixed water-spray systems over process vessels containing flammable liquids or which could be exposed to flammable-liquid fire, ensuring that relief devices do not direct vented flammable vapors onto the container, systems for diverting spilled flammable liquid to locations that would not expose process vessels, and pubhc-address systems to warn persons to evacuate locations where loss of process control could lead to a BLEVE [14]. 

---