Vent exit velocity

U= Equivalent vent exit velocity to be used in flame calc., in m/s... 

Q = Total gas rate of all valves, in dm3/s at one atmosphere and the release temperature Ujequ. = Equivalent vent exit velocity to be used in flame calc., in m/s... 

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. 

A pipe that releases gas to disperse into the atmosphere is called a vent. If the gas is burned at the tip, it is called a flare. In its simplest form, a vent or flare tip is a pipe. Sometimes the pipe diameter is reduced for the last 5 ft or so to increase exit velocity for better mixing with the air. The operating pressure of the vent scrubber can be adjusted by reducing the tip diameter to increase pressure drop across the tip. Fluidic seal., also give increased pressure drop and can be used to reduce the infusion... 

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. 

It was also observed that the number of discharge residue particles on the firing hand decreased markedly as the bullet velocity increased. One possible explanation for this is that the greatly increased suction in the wake of the faster bullet causes more particles to be sucked out of the muzzle leaving fewer to exit from other vents and to be deposited on the hand. This... 

Liquid drains, manifolded and taken to a heater for vaporizing, process safety valves, vents and thaw lines, together with the major casing vents, all culminate in a vent stack to the atmosphere. This stack should have its exit point well above surrounding equipment to prevent it from being a hazard to personnel in the event of a fire. A continuous flow of nitrogen at a velocity of 1 ft/sec can be supplied at the bottom of the vent stack to blanket all process and casing equipment from air. A check valve placed in this line provides added protection. 

Whether the emission source is a vacuum-pump discharge vent, a gas chromatograph exit port, or the top of a fractional distillation column, the local exhaust requirements are similar. The total airflow should be high enough to transport the volume of gases or vapors being emitted, and the capture velocity should be sufficient to collect the gases or vapors. 

The pressure drop in (c), the vapour venting section, is by far the largest quantity and is limited by Fanno flow, when the velocity becomes sonic at the exit. This is because the volume flow of warm cryogen vapour is much greater than the volume flow in the 2-phase cooldown section, and is several hundred times greater than the liquid input volume flow. 

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