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At least one author takes a different approach in order to avoid a need for the expression freestream static pressure. Gracey has written "The static pressure is the atmospheric pressure at the flight level of the aircraft". [15] [16] Gracey then refers to the air pressure at any point close to the aircraft as the local static pressure.
At 50 Pa, it is called the air permeability at 50 Pa and noted usually q 50 or q a50 (units: m 3 /(h·m 2)) [13] [14] Floor area A F. At 50 Pa, it is called the specific leakage rate and usually noted w 50 (units: m 3 /(h·m 2)) [13] [14] The effective leakage area (ELA) at a reference pressure is also a common metric used to characterize ...
HVAC (heating, ventilation, and air conditioning) is a major sub discipline of mechanical engineering. The goal of HVAC design is to balance indoor environmental comfort with other factors such as installation cost, ease of maintenance, and energy efficiency. The discipline of HVAC includes a large number of specialized terms and acronyms, many ...
In heating, ventilation, and air conditioning (HVAC), testing, adjusting and balancing (TAB) are the three major steps used to achieve proper operation of heating, ventilation, and air conditioning systems. TAB usually refers to commercial building construction and the specialized contractors who employ personnel that perform this service.
The fan maintains a constant static pressure in the discharge duct regardless of the position of the VAV box. Therefore, as the box closes, the fan slows down or restricts the amount of air going into the supply duct. As the box opens, the fan speeds up and allows more air flow into the duct, maintaining a constant static pressure. [11]
Rooftop HVAC unit with view of fresh-air intake vent Ventilation duct with outlet diffuser vent. These are installed throughout a building to move air in or out of rooms. In the middle is a damper to open and close the vent to allow more or less air to enter the space. The control circuit in a household HVAC installation.
Static pressure is a very valid concept even for fluids in high speed motion, or for bodies (such as aircraft) moving at high speed through the atmosphere. The static pressure of the atmosphere adjacent to an aircraft is fed to the aircraft's instruments via the static system and is used to drive the altimeter to indicate the aircraft's altitude.
Plenums are the central distribution and collection units for an HVAC system. The return plenum carries the air from several large return grilles (vents) or bell mouths to a central air handler. The supply plenum directs air from the central unit to the rooms which the system is designed to heat or cool.