COSC 325 Houston (Mechanical)
Exam/107 Questions with Answers
What division is mechanical - - Division 23
- how many Btu/H in a ton - - 12000
- What is comfortable relative humidity? - - 50%
- Air velocity - - the speed at which air moves from one point to another
- what is ideal air movement - - 40fpm
- What is the most common duct material - - sheet metal, measured in
gauge (smaller number thicker material)
- Why insulate duct work - - Condensation
- What is the average CO2 level for good indoor air quality? - - 800
- Make up air - - Air supplied to a space to replace exhausted air
- exhaust air - - Any foul or unwanted air removed from a space by
mechanical means.
- What is the normal building space requirement for fresh outside air - - 20
cubic feet per minute per person in the space
- ASHRAE - - American Society of Heating, Refrigerating and Air-
Conditioning Engineers
- 5 requirements for comfort - - proper temperature, humidity, circulation,
filtration, ventilation
- Dry Bulb Temperature - - the measurement of sensible heat
- Relative Humidity (RH) - - the amount of water vapor present in air
expressed as a percentage of the amount needed for saturation at the same
temperature.
- Dew point(dp) - - the temperature below which moisture in the air begins
to condense
, - Enthalpy (h) - - The total heat contained in a substance measured from a
baseline of 32 degrees farenheit
- Where is relative humidity found on a psychometric chart? - - the curving
lines that run from the bottom left side of the chart up to the right
- forced air system - - fuel heats air, which is blown through ducts and
vents; cool air is returned to the furnace to be reheated
- Three must common types of furnaces - - upflow, horizontal, and downflow
(counterflow)
- Upflow Furnace - - return air is supplied at the bottom of the unit and the
heated air is delivered to the bonnet above the furnace where it is
distributed through ductwork
- horizontal flow furnace - - furnace in which heated air flows horizontally as
it leaves the furnace
- Downflow Furnace - - furnace is typ. located on first floor and heated air is
pushed down into ductwork located in a crawl space or basement.
- Blower - - pump-like mechanism which generates airflow
- blowers used in forced-air systems - - propeller, centrifugal, axial
- propeller blower - - blades mounted on a central bulb
- centrifugal blower - - Consists of a scroll, blower wheel, shaft, and inlet
vanes
- axial flow blower - - -Consists of a blower wheel that works like turbine
wheel
-Used in medium to high pressure forced air heating systems
- Static Pressure - - pressure that acts through weight only with no motion
- heat exchanger - - A device that transfers heat from one substance to
another without allowing substances to mix (think radiator)
- Low-efficiency filter - - 40% of large particulate matter
- Medium efficiency filter - - 40 to 80% of common-size particulate matter
- High-efficiency particulate air (HEPA) filters - - 80 to 90 % of small
particulate matter
Exam/107 Questions with Answers
What division is mechanical - - Division 23
- how many Btu/H in a ton - - 12000
- What is comfortable relative humidity? - - 50%
- Air velocity - - the speed at which air moves from one point to another
- what is ideal air movement - - 40fpm
- What is the most common duct material - - sheet metal, measured in
gauge (smaller number thicker material)
- Why insulate duct work - - Condensation
- What is the average CO2 level for good indoor air quality? - - 800
- Make up air - - Air supplied to a space to replace exhausted air
- exhaust air - - Any foul or unwanted air removed from a space by
mechanical means.
- What is the normal building space requirement for fresh outside air - - 20
cubic feet per minute per person in the space
- ASHRAE - - American Society of Heating, Refrigerating and Air-
Conditioning Engineers
- 5 requirements for comfort - - proper temperature, humidity, circulation,
filtration, ventilation
- Dry Bulb Temperature - - the measurement of sensible heat
- Relative Humidity (RH) - - the amount of water vapor present in air
expressed as a percentage of the amount needed for saturation at the same
temperature.
- Dew point(dp) - - the temperature below which moisture in the air begins
to condense
, - Enthalpy (h) - - The total heat contained in a substance measured from a
baseline of 32 degrees farenheit
- Where is relative humidity found on a psychometric chart? - - the curving
lines that run from the bottom left side of the chart up to the right
- forced air system - - fuel heats air, which is blown through ducts and
vents; cool air is returned to the furnace to be reheated
- Three must common types of furnaces - - upflow, horizontal, and downflow
(counterflow)
- Upflow Furnace - - return air is supplied at the bottom of the unit and the
heated air is delivered to the bonnet above the furnace where it is
distributed through ductwork
- horizontal flow furnace - - furnace in which heated air flows horizontally as
it leaves the furnace
- Downflow Furnace - - furnace is typ. located on first floor and heated air is
pushed down into ductwork located in a crawl space or basement.
- Blower - - pump-like mechanism which generates airflow
- blowers used in forced-air systems - - propeller, centrifugal, axial
- propeller blower - - blades mounted on a central bulb
- centrifugal blower - - Consists of a scroll, blower wheel, shaft, and inlet
vanes
- axial flow blower - - -Consists of a blower wheel that works like turbine
wheel
-Used in medium to high pressure forced air heating systems
- Static Pressure - - pressure that acts through weight only with no motion
- heat exchanger - - A device that transfers heat from one substance to
another without allowing substances to mix (think radiator)
- Low-efficiency filter - - 40% of large particulate matter
- Medium efficiency filter - - 40 to 80% of common-size particulate matter
- High-efficiency particulate air (HEPA) filters - - 80 to 90 % of small
particulate matter
