Wind conditions

Vents and flares are intended to take contaminants released from safety valves away from work areas. However, if an elevated vent is at the level of an occupiable platform on the same or an adjacent unit, a worker may, under certain wind conditions, be subject to the nearly undiluted effluent of a vent. Whereas such elevated platforms may rarely be occupied, a heavy exposure from a vent could incapacitate a worker or cause a fall. Tanks that vent only when being filled are common causes of this concern. The usual solution is to raise the vent above any occupiable platform or, at greater cost, to scmb the vent effluent. 

Prior to an anticipated air release of a hazardous material, a circular evacuation strategy may be appropriate. Evacuation might also be initiated for a keyhole-shaped area baised on prevailing wind conditions. These strategies are illustrated below. When a large number of people aie involved, the evacuation should be staged, that is, arc ls closest to the site should be evacuated first and the evacuation zone gradually expanded. 

The pilots shall be designed for stability with wind conditions up to 160 mile per hour. 

Probably there is hide that can be done in the design of a stack to avoid this problem, although raising the elevation could be of value. In such cases, air pollution control can probably be implemented only by process reduction during unfavorable wind conditions or by permanent stack gas cleaning devices. In the lee of a chff there may be eddies of the type shown in Figure 3. 

Outdoor air is generally less polluted than the system return air. However, problems with reentry of previously exhausted air occur as a result of improperly located exhaust and intake vents or periodic changes in wind conditions. Other outdoor contamination problems include contaminants from other industrial sources, power plants, motor vehicle exhaust, and dust, asphalt vapors, and solvents from construction or renovation. Also, heat gains and losses through the building envelope due to heat conduction through exterior walls, floor, and roof, and due to solar radiation and infiltration, can be attributed to effects from external sources. 

The solar radiation absorbed on external building surfaces increases the wall surface temperature, thus leading to a change in the heat conducted through the component. In low-wind conditions, free convective flows drift up the warm external wall surface. This changes the convective heat transfer and leads to increased temperatures of supply air for natural ventilation. 

Position, size, and orientation of external objects must be specified in order to take into account both the shade cast on the exterior of the building and the modification of wind conditions. External objects are nearby buildings, trees, hills, or attached objects, such as overhangs. 

A pool fire s flame can be represented (under no wind conditions) by a vertically placed cylinder with a height h and a ground surface radius r. The view factor of... 

Normal recirculation in average installations for forced draft may run 3-10% of total inlet air, and 1-8% for induced draft towers, all depending upon the location and wind conditions during any day or season. Some towers can be arranged to have less than 1% recirculation. If conditions are suspected of being conductive to recirculation, it should definitely be allowed for in design of the tower. Recirculation increases the wet bulb temperature of entering air, increases the total air required (and hence size of... 

Under wind conditions, a complex system of pressures is set up on the external surfaces of the building, which will vary with wind speed and direction. Pressure coefficients Cp define the relationship according to the formula ... 

Disadvantages Variable flow rate and direction dependent upon wind conditions Filtration is generally impractical... 

With all louvers, there is a balance between their weatherproofing qualities and their airflow, and it is important to select a louver with the correct balance for each application. No louver can be guaranteed to be 100 per cent waterproof under all conditions, but the best ones approach this standard under normal flow and wind conditions. 

The rate of evaporation from a cooling tower is approximately 1 per cent of the circulation rate for each 5°C drop in temperature across the tower, or about 7 liters/h per ton of refrigeration. Windage losses will obviously depend on the prevailing wind conditions and the design of the tower with regard to spray elimination but, typically, these are about 0.2 per cent of the circulation rate. 

On larger multi-celled mechanical-draft towers of both counterflow and crossflow variety, the air inlets are confined to the two opposing faces and windage or drift loss is unlikely to occur, except under exceptionally high wind conditions. Here again, remedial work, depending upon the location, can be applied but at additional cost (see Figure 34.10). 

In another college laboratory building, air intake for ventilation and fume hood exhaust ducts were placed too close together on the roof. Under certain wind conditions, unpleasant odors would fill the whole building, causing many caustic comments. 

Ho et al (2004) showed for SF6 that in low wind conditions short intense rain events accelerate gas exchange in the marine environment. Extending air-sea exchange by including this process is also of interest in the context of climate change, as climate projections suggest that the intensity of rain events will increase [Roeckner et al (2006)]. 

The prevailing wind conditions should also be used to the best extent. Where rows of tanks are designed,... 

Figure 8. Averaged HbO and Hb on the left forehead under different wind conditions 2000 J. Occup. Health...

For the past few decades, manufacturers have been streamlining components and installing onboard computers to hit the propeller blades for maximum efficiency for the wind conditions. In the 1980s, the average turbine was 20 meters high with a 26-kilowatt (kW) generator and a rotor diameter of 10.5 meters. A typical turbine today can be 55 meters high, with a rotor diameter of 50 meters and a capacity of 1.6-MW. The power it produces may supply 500 homes. 

Yes, it is true that a drop of VX on the skin (if not removed) can cause death. This is, however, a misleading and panic-inspiring way to represent its lethality. The amount of VX in a warhead will normally be lethal (assuming a full minute of unprotected inhalation and optimal wind conditions) out to a radius of 100-150 yards. A hot atmosphere or a stiff breeze would limit its spread still further. 

During the high-wind condition, the split-shaft gas turbine power plant is required to produce 270 kW while at least 3.5 kW of cabin refrigeration is to be provided. 

Figure 6.41 e Combined gas turbine power plant and gas refrigeration system design at high-wind condition. 

The environmental conditions present at the time can be particularly significant. Those may include time of day, temperature, lighting, and weather conditions such as rain, fog, ice, snow, or wind conditions. 

The approximate requirement of a 14 m head of water to penetrate the surface through the largest capillaries can be related to the pressure exerted by the impact of the average raindrop in various wind conditions [13] shown in Table 4.5. 

The boundary conditions and rate constants can then be used to solve equations (E2.9.4) through (E2.9.6) for the three concentrations. The solution to these three equations would require estimates of wind conditions and release rates from the slick. All that we know is that conditions were calm but not so calm that diffusive transport was dominant. 

Obtaining desired fiber volume fraction requires precise control of winding conditions... 

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