Air-intake

Acoustical Louvers. Acoustical louvers are used in building mechanical systems when exterior walls are penetrated for fresh air intake, exhaust, or rehef air, in situations where the impact of HVAC noise is of concern in the surrounding environment. The louvers consist of a series of hoUow sheet metal blades. The bottom faces of the louver blades are perforated and the blades are filled with fibrous sound-absorbing material. Typical acoustical louvers are 20 cm (8 in.) to 30 cm (12 in.) in depth. The amount of insertion loss they provide is limited. 

The layout should ensure that exhausts are not placed close to fresh air intakes and that fire sprinkler protection for present and future requirements, eg, under stairs, storage racks, overhangs, covered walks, etc, is available. AH facility equipment must be stmcturaHy secured as well as freeze protected. 

Flare noise (roar of combustion) is the most serious because it is elevated and the sound carries. The flare can be located at a remote distance from the operating unit or surrounding community. Noise of steam injection into the burner can be reduced by using multiple no22les. Furnace noise from air intake, fuel systems, and combustion blower forced draft/induced draft (FD/ID) fans can be reduced by acoustics. The plot plan should be evaluated for noise generation and to find the means of alleviating or moving noise to a less sensitive area. 

Applications. Initial appHcations have been largely in military and aerospace areas. These include hydrauHc seals for military aircraft and fuel seals and diaphragms for both military and civiHan aircraft. Shock mounts for EZ are used on aircraft engines. Large fabric-reinforced boot seals are used in the air intake system on the M-1 tank. The material s useful temperature range, fuel and fatigue resistance, and fire resistance were determining factors in this appHcation. 

Flevated or Remote Air Intakes Elevated or remote air intakes for control rooms will help in reducing ingress of dense, flammable vapors into those rooms. Ordinarily, elevating the tip of the air intake duct 9 m (30 ft) above the ground is sufficient. Installing flammable vapor detectors in the air intake ducts provides additional protection. Controls that automatically stop air to control rooms if vapor concentrations reach 25 percent of their LFL should also be considered. 

Fan hood with protective grid for cooling air intake... 

Please notice that in a well-ventilated laboratory and a pressure cell, these experiments can be executed safely. In seven years of graduate research activity at the Chemical Engineering Department of the University of Akron, only one catalyst ignition and one real CO alarm occurred. Several false CO alarms were sounded until someone noticed that they always happened about 2 30 PM. As it turned out, one maintenance employee parked his old car right in front of the air intake to the lab ventilation. He warmed up his car for a while before he started to go home after his shift, and the motor exhaust gas set off the false alarms. 

In the forcc-ventilated or drip-proof types, the cooling air passes directly over the motor winding insulation. As a rule of thumb, a motor requires about 4,000 cfm of cooling air per thousand horsepower. Therefore, the possibilities of airborne dust and dirt collecting on the winding must he considered carefully. Filters in the air intake will lessen the hazards of this condition. Not much can be done about moisture drawn in with the cooling air, but careful selection of motor location inside ihe shelter can minimize the amount of wind-blown rain striking the motor. 

Even when the building as a whole is maintained under positive pressure, there is always some location (for example, the outdoor air intake) that is under negative pressure relative to the outdoors. Entry of contaminants may be intermittent, occurring only when the wind blows from the direction of the pollutant source. The interaction between pollutant pathways and intermittent or variable driving forces can lead to a single source causing lAQ complaints in areas of the building that are distant from each other and from the source. 

Check the outdoor air intakes to see whether they are located near contaminant sources (e.g., plumbing vents, exhaust outlets, dumpsters, loading docks, or other locations where vehicles idle). See if the space containing the HVAC system is clean and dry. Examples of problems include cleaning or other maintenance supplies... 

The elements of a PM plan include periodic inspection, cleaning, and service as warranted, adjustment and calibration of control system components, maintenance equipment and replacement parts that are of good quality and properly selected for the intended function. Critical HVAC system components that require PM in order to maintain comfort and deliver adequate ventilation air include a outdoor air intake opening, damper controls, air filters, drip pans, cooling and heating coils, fan belts, humidification equipment and controls, distribution systems, exhaust fans. 

Windage The loss of water through the air-intake louvers as a result of malfunctioning of the wind cheek walls in the lower section of the tower. 

Suppose an interstate highway passes 1 km perpendicular distance from a nuclear power plant control room air intake on which 10 trucks/day pass carrying 10 tons bf chlorine each. Assume the probability of truck accident is constant at l.OE-8/mi, but if an accident occurs, the full cargo is released and the chlorine flashes to a gas. Assume that the winds are isotropically distributed with mean values of 5 mph and Pasquill "F" stability class. What is the probability of exceeding Regulatory Guide 1-78 criteria for chlorine of 45 mg/m (15 ppm). 

This section will describe general features of airflow patterns and then present information on the dimensions and locations of recirculating (stagnant) zones around the building envelope, which determine wind pressures and contaminant dilution. This knowledge allows one to select the locations of stacks and air intakes and to calculate infiltration and natural ventilation rates. 

Wilson, D. J. 1976. Combination of air intakes from roof exhaust vents. ASHR.AFi Transactions, vol. 82, pp. 1024-1038. 

Great care is required regarding the positioning and design of the air intake to avoid drawing in local impurities and rain or snow. 

For reasons of hygiene, the inlet air should be filtered in two steps. The first filter in the air intake must be at least F5 (EU5) quality but preferably F7 (EU7). The second filter step should be effected by a filter of at least F7 (EU7) but preferably F9 (EU9) quality. If there is only one filter step, the minimum requirement is for F7 (EU7) quality. 

At Point 2, the air intake is closed, but compression does not begin until the exhaust port is covered also. Shortly after the exhaust port is closed and compression of the trapped air begins, fuel is injected at Point 3 into the cylinder through a high pressure fuel valve. At Point 4, just prior to completion of the compression stroke, a spark ignites the fucl/ iir mixture and the pressure rises rapidly through the remainder of the compression stroke and the beginning of the power stroke. 

An air conditioning system uses an assembly of equipment to treat air. Normally the assembly includes a heating system for modifying winter indoor temperature and humidity a refrigeration system for modifying summer temperature and humidity, a means to maintain indoor air quality (i.e., air filters and fresh air intake) a method of distribution of conditioned air and a control system, such as a thermostat, to maintain desired comfort conditions. 

---