Atmospheric vent pipe

Suddenly, the atmospheric vent pipe, which had been venting steam, started to blow out rather large quantities of water with the steam. 

Install flame arresters on atmospheric vents to prevent fire on the outside of the tank from propagating back into the vapor space inside the tank. Provide fire resistant insulation for critical vessels, piping, outlet valves on tanks, valve actuators, instruments lines, and key electrical facilities. Provide remote controlled, automatic, and fire-actuated valves to stop loss of tank contents during an emergency provide fire protection to these valves. Valves should be close-coupled to the tank, and must be resistant to corrosion or other deleterious effects of spilled fluids. Vessels should be provided with overpressure relief protection. 

Although venting to the atmosphere as described above is preferred, an alternative is to tie into a closed low pressure system, if available. This method may be used in the case of severely toxic fluids. Minimum length vent piping should be used. The effects of any back pressure must be thoroughly examined, since in such a case, superimposed back pressure is additive to the spring force. 

Following fires in which endotracheal tubes became ignited by surgical lasers or electrocautery in atmospheres enriched by oxygen and/or nitrous oxide, the flammability of PVC, silicone rubber and red rubber tubes in enriched atmospheres was studied [1], Ozonised oxygen was reacted with hydrogen at low pressure to generate hydroxyl radicals. Pressure in the apparatus was maintained by a vacuum pump protected from ozone by a tube of heated silver foil. On two occasions there was an explosion in the plastic vent pipe from the vacuum pump. The vent gas should have been outside explosive limits and the exact cause is not clear the editor suspects peroxide formation. 

The cold water feed can be provided by direct coimec-tion to the mains (in which case all components must be able to withstand mains pressure) or from a feeder tank (which is in an elevated position and filled from the mains through a float valve similar to the water closet-cistern float valve). For mains pressure systems most utilities or water supply authorities require the installation of a nonreturn valve. Whereas low pressure (feeder tank) systems are open to the atmosphere through a vent pipe, mains pressure systems must be protected against overpressure (due to thermal expansion of water as heated) by a pressure relief valve, as well as against collapse (implosion), which could be caused by a suction effect (vacuum formation) in case of an aceidental water discharge, by an air intake (or breather) valve. 

Sponge coke, 46—48, 70 Stack damper, 317-318, 320 process heaters, 317 Stacked paper plates, 94 Stainless steel, 416-418, 424-425 field identification of pipe, 417-418 cracking, 424-425 Start-up stack, 123 Start-up tips (sulfur plant), 134 Start-up (pump cavitation), 246-247 Start-up (sulfur recovery), 122-124 oxygen supply, 123 atmospheric vent, 123-124... 

Each main steam line goes from its steam generator and passes through the containment boundary. The first valve encountered in each line is the main steam isolation valve, which is outside the containment boundary each isolation valve has a bypass valve in parallel with it. Beyond the main steam isolation valve in each of the two steam lines are the six steam safety valves every one of these safety valves vents to atmosphere through a discharge pipe and vent stack. Downstream of the safety valves is the power-operated atmospheric relief valve, which vents to atmosphere through a vent pipe and silencer. The operation of the power-operated relief valves is automatically controlled by steam line pressure during plant operations the power-operated relief... 

When the air-water mixture enters the larger, vertical stand-pipe in Fig. 1.2, the velocity of the air-water mixture goes down. Some of this reduced kinetic energy is converted back into pressure. This I know because the pressure in the stand-pipe is atmospheric pressure. This has to be because the top of the stand-pipe is the 3-inch vent pipe sitting on the roof of my house. The air sucked down the toilet bowl escapes through this 3-inch vent. If a bird s nest or snow clogs the vent, then the trapped air builds pressure in the stand-pipe. The backpressure from the stand-pipe restricts the flow of water from the bowl, and the toilet can no longer flush properly. 

During a rise in ambient temperature, solvent-laden air in the headspace of storage tanks expands and is partially expelled into the atmosphere through a vent pipe. When the temperature drops, the process reverses itself, and fresh solvent-free air enters the headspace. Subsequent cycles of rising and falling temperature cause a cumulative loss in solvent. An accurate calculation for this loss would require a knowledge of the time- and space-dependent concentrations and temperatures in the tank, and would thus call for the... 

Studied is 2 cm. The minimum diameter of the pellet to be studied is 0.4 cm. It is not anticipated that reactions will be carried out below 400°C or above 1000°C. From the work of previous investigators it is not expected that the rate of reduction will exceed 6.2% per min. Work will be carried out at or near atmospheric pressure. Errors exceeding 2% are not tolerable and for this reason water vapor in the reactor should be kept below 2%. The vent pipe for the system must be 50 ft long. 

Deflagration Arresters The two types of deflagration arrester normally considered are the end-of-line arrester (Figs. 26-23 and 26-24) and the tank vent deflagration arrester Neither type of arrester is designed to stop detonations. If mounted sufficiently far from the atmospheric outlet of a piping system, which constitutes the unpro-tec tea side of the arrester, the flame can accelerate sufficiently to cause these arresters to fail. Failure can occur at high flame speeds even without a run-up to detonation. 

Cracking imposes an additional penalty in a vacuum unit in that it forms gas which cannot be condensed at the low pressures employed. This gas must be vented by compressing it to atmospheric pressure. This is accomplished by means of steam jet ejectors. Ideally, it would be possible to operate a vacuum pipe still without ejectors, with the overhead vapors composed only of steam. In practice, however, leakage of air into the system and the minor cracking which occurs make it necessary to provide a means of removing non-condensibles from the system. In addition to the distillation of atmospheric residuum, the lube vacuum pipe still is also used for rerunning of off specification lube distillates. 

Credit for additional height of the flame center for multiple valve installations may be taken by clustering the safety valve discharge pipes to the atmosphere. The following procedure should be used for determining equivalent diameter and exit velocity to be used in the flame center calculation. Diameter and velocity are based on the total acmal area of the clustered vents. 

Often, the blowdown valve is routed to a closed flare system, which services other relief valves in the facility to ensure drat all the gas is vented or flared at a safe location. In such instances, a separate manual blow -down valve piped directly to atmosphere, with nothing else lied in, is also needed. After the compressor is shut down and safely blown down through the flare system, the normal blowdown valve must be closed to block any gas that may enter the flare system from other relief valves. The manual blowdown valve to atmosphere protects the operators from small leaks into the compressor during maintenance operations. 

The most important safety devices in a production facility are the pressure relief valves, which ensure that pipes, valves, fittings, and pressure vessels can never be subjected to pressures higher than their design pressures. Relief valves must be designed to open rapidly and fully, and be adequately sized to handle the total flow of gas and liquids that could potentially cause an overpressure situation. They relieve the pressure by routing this stream to a safe location where it can be vented to atmosphere or burned. 

Relief valves vented to the atmosphere should have tail pipes equal to or larger in diameter than the relief valve outlet that extend vertically a minimum of one foot above building eaves, or eight feet above adjacent platforms on operating areas. The tail pipes should be provided with a drain located such that the exhaust through the drain hole does not impinge on vessels, piping, other equipment or personnel. 

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