HVAC Flashcards
_____ the simultaneous control of the temperature, humidity, motion and purity of the air in a confined space.
air-conditioning
What are the 4 functions or elements of air-conditioning?
- cooling and de-humidifying of air
- heating or humidifying of air
- cleaning of air or filtration
- circulation of air
What are the 4 air-conditioning standards?
- cooling and de-humidifying
- heating and humidifying
- air motion
- air supply
______ for summer cooling, temperatures of 68 deg to 74 deg F and 50% relative humidity are a frequent design average.
cooling and de-humidifying
For summer cooling, temperature of __ to ____ deg F and 50% relative humidity.
68 to 74
_____ for winter cooling, temperatures of 70 deg to 75 deg F and relative humidity of 30% to 35% are found most satisfactory.
heating and humidifying
For winter cooling, temperatures of ____ to ____ deg F and relative humidity of 30% to 35%.
70 to 75
_____ air velocity should average 4.57 to 7.6 meters per min measured 36” above the floor.
air motion
For air supply, a 5 cuft to 7-1/2 cuft of air per minute per person (5-71/2 cuft/min/pers). In rooms where ______
smoking is not allowed
For air supply, a 25 cuft to 40 cuft of air per minute per person allowed in rooms where _____.
smoking is permitted
What are the 4 methods of cooling and de-humidifying?
- passing the air through a spray of cold water
- passing the air through coils containing cold water
- passing the air through coils containing the refrigerant itself; in this case the coils are called “direct expansion” coils
- passing the air through a combination of sprays and coils
_____ is a gas at normal temperature and pressure. It is first subjected to high pressure in a compressor which raises its boiling point and temperature.
Freon
____ is a refrigerant used for cooling.
Freon
______ is based upon the alternate liquefying and evaporating of a volatile liquid with a low boiling point usually Freon 12 (Dichlorodiflouromethane) or Freon 11 (Trichloromonoflouromethane) during which processes it respectively gives off and takes in heat.
mechanical refrigeration
What are the 6 desirable properties of Freon?
- high heat of vaporization
- moderate pressure change for low to high temperature range
- non-toxic
- incombustible
- non-explosive
- non-corrosive
What are the 3 types of air-conditioning systems?
- central systems
- split type air conditioning system
- window type air conditioning system
What are the 3 parts of the refrigeration plant?
- compressors
- condensers
- evaporators
What are the 2 types of compressors?
- piston type or reciprocating compressors
- centrifugal compressors
_____ for tonnages up to 100 tons
piston type ot reciprocating compressors
_____ are quieter, have fewer vibration problems, require less maintenance and with better operating control.
centrifugal compressors
What are the 2 types of condensers?
- air-cooled condensers
- water- cooled condensers
_____ are used in unit and packaged-type air- conditioners up to 3 tons refrigeration.
air-cooled condensers
What are the 3 types of water-cooled condensers?
- double-piped condensers
- shell and tube condensers
- evaporative condenser
What are the 2 types of evaporators?
- shell and tube heat exchanger
- direct expansion coils (coils containing the refrigerant itself)
_____ is similar in operation to the shell and tube condenser.
shell and tube heat exchanger
____the refrigerant is expanded into a shell enclosing the tube through which the water flows.
shell and tube heat exchanger
______ may either be installed in the spray chamber so that the water sprayed into the air comes into contact with the cooling coils or the air itself comes into direct contact with the cooling coils, as in the window type unit.
direct expansion coils
What are the 2 cooling and de-humidifying equipments?
- water sprays
- cooling coils
What are the 2 heating and humidifying equipments?
- tempering coils
- water heaters
____ contains steam and are used to heating the air ie., preheaters and reheaters.
tempering coils
_____ is used for heating the water which will be used in the spray chamber to add heat and humidity to the air.
water heaters
What are the 4 types of filters?
- dry filters
- viscous filters
- water filters
- eliminator plates
_____ consist of wire frames enclosing felt, cotton or sponge through which the air is screened.
dry filters
_____ consist of metal deflecting plates or screens coated with viscous oil.
viscous filters
_____ consist of corrugated galvanized iron sheets placed 1-1/8” apart which deflect the air flow about 30 deg catching the wet dust on the surfaces.
eliminator plates
What are the 3 air distribution equipment?
- ducts
- fans
- air outlets
_____ are usually of galvanized sheet metal, or aluminum sheets, usually rectangular in section, depending on the aspect ratio*, although circular ducts are also used for high velocity systems.
ducts
Aspect Ratio of the long side to short side; not to exceed 5:1 although ______ is preferred.
4 or 3:1
What are the 2 types of fans?
- centrifugal fans (radial fans)
- propeller or axial fans
____ are intended for moving air at comparatively high pressures and are commonly used in duct systems.
centrifugal fans (radial fans)
_____ are commonly used for wall exhausts
propeller or axial fans
_____ are madde for two locations: wall and ceiling.
air outlets
What are the 2 types of wall outlets?
- vaned outlets
- perforated grills
What are the 3 types of ceiling outlets?
- plaques
- perforated panels
- perforated ceilings
What are the 2 control equipment?
- sensing devices
- actuating or operating devices
What are the 3 sensing devices?
- humidistat
- thermostat
- pressure regulators
____ or Hygrostat is a controller, sensitive to the amount of humidity in the air.
humidistat
____ is a controller which responds to changes in temperature.
thermostat
_____ are instruments sensitive to changes in pressure. They may control a single pressure or a differential between two pressures.
pressure regulators
What are the 3 actuating or operating devices?
- dampers
- control valves
- relays
_____ control the flow of air and are in the form of louvers.
dampers
______ are valves with variable orifices which are moved by motors to present smaller or larger openings as directed by a thermostat.
control valves
_____ are devices that use electrical energy to amplify or convert the power of a thermostat or other controllers so that the resultant force will be sufficient and adaptable to operate a valve or damper.
relays
What are the 4 types of heating systems?
- mechanical warm air heating system
- steam heating system
- hot water heating system
- radiant panel heating system
What are the 2 steam heating systems?
- air-vent system (one-pipe gravity system)
- vacuum system (two-pipe steam heating system)
What are the 2 hot water heating system?
- one-pipe hot water heating system
- two-pipe hot water heating system
_____ is any inadvertent physical contact with power transmission equipment, prime movers, machines or machine parts which could result from slipping, falling, sliding, tripping or any other unplanned action or movement.
accidental contact
______ is the process of treating air so as to control simultaneously its temperature, humidity, cleanliness and distribution to meet the requirements of the conditioned space.
air conditioning
______ is a closed vessel for heating water or for application of heat to generate steam or other vapor to be used externally or to itself.
boiler
_____ is the total horsepower of all engines, motors, turbines or other prime movers installed, whether in operation or not.
capacity of works project or plant
_____ is a mechanical device for the purpose of increasing the pressure upon the refrigerant.
compressor
_____ is a vessel or arrangement of pipes or tubing in which vaporized refrigerant is liquefied by the removal of heat.
condensers
_____ is a boiler or unfired pressure vessel that has been inspected by the Building Official and declared unsafe or disqualified and power stamped or marked designating its rejection.
condemned boiler or unfired pressure vessel
_____ means a machine for lifting or lowering a load and moving it horizontally, the hoisting mechanism being an integral part of the machine.
crane
_____ passageway made of sheet metal or other suitable material not necessarily leak tight, for conveying air or other gases at low pressure.
duct
______ means that the moving parts of a machine are so guarded that physical contact by any part of the human body is precluded or prevented.
enclosed
_____ does not however prohibit the use of hinged, sliding or otherwise removable doors or sections to permit inspection, lubrication or proper maintenance.
enclosed
_____ is that part of the AC/refrigeration system in which liquid refrigerant is vaporized to produce refrigeration.
evaporation
____ is an inspection made on boiler during operation.
external inspection
_____ Shielded, fenced or otherwise protected by means of suitable enclosure guards, covers or standard railings, so as to preclude the possibility of accidental contact or dangerous approach to persons or objects.
guarded
_____ is inspection made when a boiler is shut down, with hand holes, manholes, or other openings opened or removed to permit inspection of the interior.
internal inspection
_____ is a vessel permanently connected to a system by inlet and outlet pipes for storage of a liquid refrigerant.
liquid receiver
_____ is a boiler mounted on a self-propelled track locomotive used to furnish motivating power for traveling on rails.
locomotive boiler
____ is a boiler operated at pressures not exceeding 1.05 kgs/sqm with steam or water temperature not exceeding 250oF.
low pressure heating boiler
____ is the driven unit of an equipment.
machine
_____ is an enclosure for housing the hoisting mechanism and power plant.
machine house
_____ is any or all moving parts of a machine.
machine parts
_____ includes steam plants, internal combustion engine plants, hydraulic power plants, pumping plants, refrigerating plants, air conditioning plants, mill shops, factories, foundries, shipyards, etc. containing any mechanical equipment, machinery or process, driven by steam, internal or external combustion fuel, electricity, gas, air, water, heat, chemicals or other prime movers.
mechanical works plant
____ is that part of a machine which performs an operation on the stock or material and/or that place or location where stock or material is fed to the machine.
point of operation
____ is an internally fired boiler which is self- contained, primarily intended for temporary location.
portable boiler
_____ is an engine or motor operated by steam, gas, air, electricity, liquid or gaseous fuels, liquids in motion or other forms of energy whose main function is to drive or operate, either directly of indirectly, other mechanical equipment.
prime mover
_____ is an equipment designed and operated for a specific purpose.
process machine
_____ is a substance which produces a refrigerating effect by its absorption of heat while expanding or evaporating.
refrigerant
_____ is the useful refrigerating effect equal to 12,000 BTU/hour; 200 BTU/min.
ton of refrigeration
____ is a vessel in which pressure is obtained from an external source or from an indirect application of heat.
unfired pressure vessel
____ is the process of supplying or removing air by natural or mechanical means to or from any space.
ventilation
What are the 4 locations of boilers?
- inside buildings
- outside the building at a distance not less than 3.00 m from the outside wall of the main building
- one meter away from any wall
- shall be provided with sufficient room for removal/replacement of tubes thru the front or rear
Boiler rooms shall have at least _____ separate exits.
two
Boilers of more than ____ sqm heating surface shall each be provided with two means of feeding water, one steam driven and one electrically driven, one pump and one injector.
46
Each boiler shall have at least _____ safety valve.
one
Each boiler shall have a steam gauge, with a dial range of not less than ____ times and not more than twice the maximum allowable working pressure.
1-1/2
Upon the completion of the installation, the Building Official shall conduct an inspection and test, after which a certificate of operation for a period not exceeding _____ shall be issued upon payment of the required inspection fees.
one year
The temperature and humidity of the air to be used for comfortable cooling shall be maintained at _____ deg F effective temperature at an air movement from 4.57 to 7.60 MPM within the living zone.
68-74
____ shall be constructed entirely of non-combustible materials such as steel, iron, aluminum or other approved materials.
ducts
____ shall be provided at all automatic dampers, fire dampers, thermostats and other apparatus requiring service and inspection in the duct system.
access doors
Not more than ____ kgs of refrigerant in approved containers shall be stored in a machine room at any given time.
136
Refrigerant piping crossing a passageway in any building shall not be less than ___ m above the floor.
2.3
In a refrigerating system containing more than ____ kgs, stop valves shall be installed in inlets and outlets of compressors, outlets of liquid receivers, and in liquid and suction branch header.
9
_____ shall be provided with drain pipe or plastic tubing for discharging condensate water into a suitable container.
window type ACs
Window type AC installed on ground floors of buildings shall not be less than _____m from the ground.
2.13
Window type ACs shall be provided with ____ if the exhaust is discharged into corridors/hallways/ arcades/sidewalks etc.
exhaust ducts
Window type ACs installed along corridors/hallways/above the first floor shall not be less than ____m above the floor level.
2.13
____ shall, as much as possible, run parallel to building walls.
piping
Piping ____mm in diameter and above shall be flanged. Smaller sized pipes may be screwed.
100
_____ piping shall not be used for steam.
galvanized
What are the 7 color coding piping?
- steam division
- water division
- oil division
- pneumatic division
- gas division
- fuel oil division
- refrigerating division
