CNST 2321

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Absolute humidity

The amount of water in the air (measured in grains or pounds of water per pound of dry air):

Net positive suction head (NPSH) is which of the following?

The inlet pressure required to prevent cavitation

Which heat recovery system (ERU) will result in the highest cooling savings?

Enthalpy wheel

To prevent a destructive event of a short circuit, protective devices ( fuses or circuit breakers) must have an interrupting capacity conforming to which of the following?

Equal to or greater than the calculated short circuit current

What fluid is used in the vapor compression cycle?

Refrigerant

Match

- Air pressure in a duct - in.w.c (inches of water column) - Water pressure in a pipe -ft of head or psi - Air velocity in a duct - ft/min - Water velocity in a pipe - ft/sec

What piping materials might be used for a fire protection automatic sprinkler system?

- Black steel with welded fittings - Copper

Which of the following is NOT a type of compressor used in a chilled water system?

A) TURBINE b) Reciprocating c) Scroll d) Centrifugal e) Screw

According to the (NEC), which of the following is a "bathroom" ?

An area with a toilet and sink

What are normal materials of construction for coils?

Copper tubes and aluminum fins

Which is the normal flow in a heating coil?

Counter flow, which is water in on the leaving air side

Most telecommunications systems operate on DC circuitry. Why?

DC devices are more sensitive than AC

A "domestic water system" includes the water distribution system, the fire protection system, and the industrial processing water system

False

A branch circuit is the portion of the wiring that connects the feeder to distribution center

False

A feeder schedule is the most important schedule of power system design

False

Dew point is the temperature at which moisture begins to condense and when the relative humidity reaches 80%

False

Fire tube boilers are so named because the water travels through the inside of steel tubes

False

In HVAC, load is the amount of people or equipment allowed in a given room

False

In an alternating current (AC) system, current flow is always in one direction flow from negative to positive

False

Pipe hangers support the pipes from above to protect from vibration and shock

False

The tendency of an assembly to conduct heat (U-factor) or heat transfer is directly proportional to R and inversely proportional to U

False

Refrigerants transfer heat (cooling) by changing phase from solid to vapor

False (Liquid to vapor)

Dew point is when the humidity level reaches 75% at a given temperature

False (100%)

What type of valve would be a good choice for isolation or shut off service?

Gate valve

What is the primary purpose of a plumbing trap?

To prevent sewer gas from entering the building

Heating and cooling the ventilation air (outside air) requires considerable energy, which is wasted unless the energy is recovered from indoor exhaust air

True

If refrigerant is used in the air conditioning coil (evaporator), refrigerant to air exchange, the system is generally termed direct expansion (DX)

True

In HVAC terminology, a zone is an area where temperature is controlled by a single thermostat

True

Installation of fire safety equipment must be in compliance with code requirements from Chapter 9 of International Building Code and the fire marshal must be consulted

True

Which HVAC System is used extensively in commercial buildings despite potential "stuffiness" during light load conditions and is least flexible for adding r changing zones after instalation?

Multiple zone VAV

The actuated assembly is _____ _____ if flow is prevented when the control pressure (or other signal) is absent

Normally closed

"The ampacity of an individual feeder shall not be required to be larger then the ampacity for the entire building" is an example of NEC ______ rules:

Permissive

What is the major difference between shell and tube vs plate and frame heat exchangers?

Plate and frame can achieve small temperature difference between liquids

What is the unit of measure for water pressure in a pipe?

Psi

Which statement is true about refrigerant cooling coils?

Refrigerant changes from liquid to vapor in the coil

The primary objective of a fire protection system is to

Save lives and protect property

_____ is the primary sense of fire-related deaths

Smoke

A recirculating system using a pump is a method to keep hot water available quickly at a remote plumbing fixture

True

According to the NEC all connections or splices of wires and cables must be made within code-approved boxes that are accessible for inspection and service

True

Conduction also depends on the insulating quality of the wall or envelope, which is measured by resistance to heat transfer: the R-value

True

Control dampers are used to control the flow of air and can be direct-acting or reverse-acting

True

Drainage in buildings consists of three major components: sanitary waste, storm water, specialty waste (toxic, radioactive, chemical (acid), etc, ).

True

Good indoor environmental quality results in real economic benefit from productivity. These benefits should be included in life-cycle cost analysis.

True

Ground Fault Circuit Interrupter (GFCI) will trip or cut out the circuit if an imbalance of current flow is detected.

True

HVAC systems use fluids to transport heat and cold to satisfy loads and maintain comfort. Such fluids include air, water, steam, and refrigerant

True

Heating and cooling loads represent how much heat is lost or gained and must be made up or removed by the system

True

Heating and cooling the ventilation (outside) air requires considerable energy, which is wasted unless the energy is recovered from the exhaust air

True

Single-zone reheat is a constant-volume system used for air-conditioning when humidity control is especially important

True

A ______ circuit is the portion of the wiring that connects the utility service to the panel board

feeder

What is "connected load"?

sum of all electrical loads connected to the system, on or off

What is the primary purpose of a plumbing vent line?

To equalize pressure across traps

Methods of producing indoor cooling include the following

- Dessicant cooling - Evaporative cooling - Absorptin cooling - Vapor compression cooling?

Variable frequency drives often take the place of motor starters, and can provide which of the following functions?

- On-off control - Energy savings - Soft start

Refrigerants with their properties

- Was a replacement for R-22 - R-134A - Banned by Montreal Protocol due to high ODP - R-12 - On its way out due t high GWP - R-410A - Environmentally friendly, but flammable and toxic - R-717

What are functions of an uninterruptible power system (UPS)?

-Allow time for a generator to start when there is a power outage - Provide high quality power interns of voltage and frequency -Keep critical equipment running in the event of a utility power outage - Allow time to shut down in an orderly fashion

Multi Zone VAV systems are

1 used extensively in commercial buildings 2 have pot 3 least f

Match the ASHRAE Standard numbers with their topics

1) Energy conservation is covered in Std - 90.1 2) Ventilation is covered in Std - 62.1 3) Thermal comfort is covered in Std - 55 4) Measures filter performance - 52.1

Magnitude of energy consumption for a typical office building in midwest USA. (1 highest)

1) HVAC 2) Lighting 3) Appliances 4) Hot water

List the four components of the vapor compression cycle in order

1) compressor 2) condenser 3) expansion valve 4) evaporator

What are the three circuits in a chilled water system?

1) refrigerant 2) chilled water circuit 3) condenser circuit

Which of the following statements are true regarding DX systems?

1) they include roof top units and PTAC units 2) they can have condensers remote from the fan coil unit 3) refrigerant is used in the air conditioning coil (evaporator)

Positive pressure is needed in a domestic water system to:

1. Establish a flow in the distribution system and through the plumbing fixtures or equipment 2. Prevents water from being contaminated by external sources 3. Sufficient to overcome any pressure loss due to friction and elevation

What is the unit of measure for water velocity in a pipe?

1. Gpm 2. Ft/sec

Outside weather conditions affect heating and air conditioning loads from introduction of outside air for:

1. Infiltration 2. Ventilation 3. Conduction

What are the three conditions that affect heating and air conditioning loads from introduction of outside air?

1. Infiltration 2. Ventilation 3. Conduction

Comfort for building occupants is affected by a number of environmental variables, including the following:

1. Temperature 2. Airflow 3. Humidity 4. Radiation

All HVAC systems require some form of control to accomplish their task of controlling one or more of the following properties

1. Temperature 2. Pressure 3. Flow rate 4. Humidity 5. Speed (fixed or variable) 6. Time

What are the methods of control for air systems

1. Varying the temperature of the air supplied while holding the flow constant 2. Varying the flow of warm or cold air supplied while holding the temperature constant 3.varying both the temperature and the flow of air supplied or turning the system on or off

What nominal single phase system voltage is used in residential?

120/240 (120/208 for three phase)

which of the following conductors has the largest diameter?

2/0 (smaller number, bigger diameter. 14, 8, 2/0, 16)

A three-phase circuit has a line-to-neutral voltage of 120 volts. What is the line-to-line voltage?

208 volts

The slope of the horizontal drainage pipe shall not be less than ______ for a 24 ft section of 4" drain pipe

3"

In general, the overall cross-sectional area of all conductors shall not exceed __________ percent of the cross-sectioned area of the conduit when there are three or move conductors in the conduit

40%

How much power is dissipated by passing 10 amps through a 5-ohm resistor?

500 watts

Energy codes recommend a maximum winter indoor design temperature of ____ and a minimum summer indoor design temperature of ____.

72°F / 75°F

According ASHRAE, boilers and furnaces which condense flue gas in second heat exchangers generally have annual fuel utilization efficiency (AFUE) in what range?

92% to 98.5%

To avoid frequent start-up of the fire pump, a small pressure maintenance pump is installed in parallel with the fire pump. What is this device called?

A "jockey" pump

_____ humidity, also known as the humidity ratio (W), is the amount of water in the air and is measured in grains or pounds of water per pound of dry air

Absolute

What kind of pumps are most used in HVAC applications (e.g. chilled water)?

Centrifugal

What type of valve would be used to prevent backflow?

Check valve

Which of the following installations is NOT covered by the NEC?

Electric utility power lines within city limits

What type of cooling towers uses a fan to blow air through the tower?

Forced-drafted counterflow

Reverse osmosis is used for water purification and is the name for which of these phenomena?

Forcing water from strong solution to weak solution through a membrane by pressure

which of the following valves is used for throttling or regulating?

Globe valve

The device in a PV system which allows the solar power to run AC appliances is which of the following?

Inverter

Which of the following lamp types is generally the most energy efficient?

LED

The __________ diagram is also called an elementary diagram, which is the simplest way to illustrate the operating principle of on electrical circuit

Ladder

Extra low voltage systems are defined as which of the following?

Less than or equal to 50 volts

Light sources can be grouped into four major classes. Which of the following is not one of those classes?

Low intensity discharge

Filters are rated based on which of the following systems?

MERV rating value

The management level hardware of a distributed control system is generally which of the following?

Mainframe computer

The secondary objective of a five protection is to

Minimize interruptions of service

Which of the following cable types is commonly used in residential construction?

NM

The National Electrical code is published by __________.

National Fire Protection Association (NFPA)

Heat, fuel, and _____ make up the three sides of the fire triangle

Oxygen

Which HVAC system must be placed on an outside wall?

PTAC

A ______ schedule is the most important schedule of power system design

Panel

Two basic properties of air-water mixtures are:

Temperature and humidity

The "normal" position of an actuated value or damper is which of the following?

The position (open or closed) that the device assumes with no signal

Kirchhoff's first law states which of the following?

The sum of the currents at a junction is zero

The "connected load" sum of all electrical loads connected to the system, on or off

True

The common methods of joining piping and velves include flanges , welded, glued, threaded, grooved, and clamped.

True

The primary purpose of piping and valves in the commercial building is to move fluid

True

The purpose of the National Electrical Code (NEC) is the practical safeguarding of persons and property from electrical hazard

True

When air is the most common medium used to deliver a heating or cooling effect to a space, the delivery system is called an air-handling system consisting of an air-handling unit, ductwork, and air devices

True

contactors and relays are remote- control power transmitting devices

True

Which of following fans would be appropriate for kitchen grease exhaust?

Upblast roof ventilator

The electromotive force (EMF) or potential difference that causes an electric current to flow is called

Voltage

The electromotive force (EMF) or potential difference that senses on electric current to flow is called:

Voltage

Ohm's Law states which of the following?

Voltage is proportional to current and resistance

Low Voltage Systems according to the NEC are:

nominally below 600V


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