Airflow properties and Air Handling Flashcards
What is Relative Humidity ?
- Expressed as a percentage %
- the actual humidity compared to the max humidity
What is Volume Flow Rate?
Is the amount of 3 dimensional sections of air flowing past a point in the ductwork if a system
Volume Flow Rate Units?
Metric: litres per second (l/s or lps)
Imperial: cubic feet per minute ( cfm, ft3/min)
What is Dew Point?
Is an air condition in which dry and wet bulb temperatures are the same. It is the point where water vapour in the air condenses
Mass Flow Rate units
Ibs/min
Unit for total heat
Btu/hr
Where are Hepa Filters used? (High efficiency particulate arrestance)
- medical facilities
- computer labs
- specific areas that need really clean air
What is Merv Rating filter 1 - 4 good for?
Basic residential furnace 10 microns or larger
What’s a curved air foil?
High air flow rates and high static pressure
What are V - Belts?
Standard industrial belt
Letters A - E
A-34 (34 indicates inside circumference)
What is an Axial fan?
-Air flow is parallel to impellers shaft
- pushes air
- handles large volumes of air at low static pressures
What’s a tube axial fan?
- Propeller In a tube
- more efficient than straigh axial
- Air discharged in a spiral pattern
What’s a vane axial fan?
- Tube axial fan with straightening vanes
- more efficient than tube axial (no spiral)
- fan blades have adjustable pitch
What are centrifugal radial blade fans?
- provides high pressure at high speeds
- used as cooling fans for electric motors
Backward curved fan?
- More efficient than forward curved blades
- can be noisey
- blades inclined in the opposite direction of rotation
