2nd Volume - HVAC/R Fundamentals Flashcards
What is the most common cause of electric shock?
extension cord abuse
What are two basic groups of safety directives that apply to the HVAC/R career field?
AFIs and Air Force Occupational Safety and Health (AFOSH) standards
What directive states safety policy, sets up mishap prevention program requirements, and assigns responsibilities for program elements?
AFI 91–202, The USAF Mishap Prevention Program
Which regulation establishes policy and assigns responsibilities for managing the AFOSH program and applies to all Air Force civilian and military personnel worldwide, including members of the Air National Guard and Air Force Reserve?
AFI 91–301, Air Force Occupational and Environmental Safety, Fire Protection and Health (AFOSH) Program
Which regulation prescribes safe practices and procedures for personnel engaged in maintaining and operating electrical systems and facilities?
AFI 32–1064, Electrical Safe Practice.
What has the Air Force set up to protect personnel from the harmful effects of hazardous noise?
Hearing Conservation Program
A hazardous noise exists if you have to —BLANK— to be understood.
shout at 3 feet (a loud voice at 1 foot)
When working on circuits over —BLANK—, workers must not work alone; instead, a safety observer must be present.
300 volts
What are the four basic causes of burns?
Thermal, Chemical, Electrical, and Nuclear
Which burns are caused by excessive heat?
Thermal
What are the three categories of thermal burn damage?
First, Second, and Third Degree
Which burn classification is normally associated with sunburns where there’s a reddening of the skin but doesn’t blister or burn through the different layers of skin?
First degree
Which burns are characterized by blisters appearing on the first layer of skin?
Second degree
Which is the most severe burn a person can get and damages the skin through the top layer and sometimes through the fat that lies beneath it?
Third degree
Which burn destroys the nerve endings?
Third degree
What happens to the area of a third degree burn?
becomes dry, leathery, and discolored (charred, brown, or white)
What are two types of cross connections?
Inlet and Direct (or pressure)
What is any actual or potential link or path of flow between a potable water supply and a source of contamination or pollution?
cross connection
What type of connection is used to fill a receptacle that’s open to the atmosphere?
Inlet-type connection
What is the reversal of the normal water flow in a system?
Back-siphonage
What is the reversal of the normal water flow in a system caused by a negative pressure in the supply piping?
Back-siphonage
What type of connection is one in which the potable waterline is connected to a nonpotable line or pressurized vessel?
Direct-or pressure-type connection
The backflow of —BLANK— into a potable water supply would cause a minor change in the water quality
a Class I substance
The backflow of —BLANK— into a potable water supply could cause illness or death if consumed by humans.
a Class III substance
What are the five types of backflow prevention devices?
- Air gap, 2. Atmospheric-type vacuum breaker, 3. Pressure-type vacuum breaker, 4. Double check valve, 5. Reduced pressure backflow preventer
What is a physical separation of the potable and nonpotable system by an air space?
Air Gap
For an air gap to work properly, the vertical space between the supply line and the flood-level rim must be at least
two times the inside diameter of the supply pipe and it can’t be less than 1 inch and need not be more than 12 inches
Which type of breaker is designed to prevent back-siphonage of Class I substances into a potable water supply?
Atmospheric-type vacuum breaker or Pressure-type vacuum breaker
Which type of breaker prevents a vacuum from occurring on the discharge line by allowing air to enter the line?
Atmospheric-type vacuum breaker
Which breaker must be installed on the discharge side of the last control valve and above the highest usage point?
Atmospheric-type vacuum breaker
Which breaker can’t be used under continuous pressure or be subjected to backpressure?
Atmospheric-type vacuum breaker
Which breaker device has a moving, spring-loaded disc float and check valve in the body?
Pressure-type vacuum breaker
Which device is used in direct connection-type systems to prevent the backflow of Class I and II substances into the potable water supply?
Double check valve
What valve can be used in continuous pressure systems that are subject to backpressure or back-siphonage?
Double check valve
Which device has two independently operating, spring-loaded check valves in the body?
Double check valve
Which type of backflow preventer may be used on all direct connection-type systems?
reduced pressure backflow preventer
What type of backflow preventer is designed to prevent the backflow of all three classes of substances into the potable water supply?
reduced pressure backflow preventer
Which backflow preventer is used in continuous pressure systems that are subject to backpressure or backsiphonage?
reduced pressure backflow preventer
Which backflow preventer is equipped also with two independently operating spring-loaded check valves, which are located in the body?
reduced pressure backflow preventer
Who is responsible for reporting unsafe acts or conditions?
Everyone
Which AFI covers areas relating to electrical installations and systems?
32-1064
Which AFOSH standard covers areas relating to working around machinery?
91-12
Select the statement that best describes your individual responsibility relative to the Air
Force Occupational Safety and Health (AFOSH) program?
Report safety, fire, and health hazards promptly.
Leaving tools scattered about is an indication of
Poor housekeeping
What types of mishaps must be reported to the safety staff?
All mishaps
Select the Air Force program that was established to protect personnel from the harmful effects of hazardous noise.
Hearing Conservation Program.
What is the best protection against noise damage?
Isolate systems or pieces of equipment that exceed acceptable noise limits.
A safety observer must be present if you are working with a voltage over
300 volts
Mechanical equipment that has exposed moving parts must be completely enclosed in a suitable metal guard if the equipment is located above the floor by less than
8 feet
When working on rotating equipment, you should avoid
wearing loose clothing
Second-degree burns are characterized by
blisters appearing on the first layer of skin
When a thermal burn victim has had his or her clothes on fire, and the skin and clothes are still hot, you should immerse them in
cold water for a maximum of 10 minutes
Which burn treating statement is correct?
Cover the burned area with a dry, sterile dressing to decrease heat loss
What type of cross connection exists if the spout on a sink faucet extends below the overflow rim?
Inlet
Which type of backflow preventer is used to prevent back-siphonage of Class I substances and may be used under continuous pressure but not subjected to back-pressure?
Atmospheric-type vacuum breaker.
Which type of backflow preventer can be used on all direct connection-type systems to
prevent the backflow of all three classes of substances into the potable water supply?
Reduced pressure backflow preventer.
Which backflow preventer is used in continuous pressure systems that are subject to backpressure or backsiphonage?
reduced pressure backflow preventer
Which backflow preventer is equipped also with two independently operating spring-loaded check valves, which are located in the body?
reduced pressure backflow preventer
The size of a pipe is referred to as
nominal
What are the two grades of steel pipe?
- Standard, or schedule 40, 2. Extra strong (or heavy), or schedule 80
What are the most commonly used materials for piping?
Steel, Iron, Copper, and Plastic
What is galvanized pipe is coated with?
zinc
What is galvanized pipe mostly used for?
domestic water applications
What piping does HVAC/R technicians primarily deal with?
black iron piping
What are the four most common types of fittings used in HVAC/R systems?
- Thread, 2. Flange, 3. Flared, 4. Compression Joint
What type of fittings are used mostly on steel piping?
Thread and flanges
What type of joints are used with copper lines?
Flared and compression
How are pipe fittings measured?
by Inside Diameter, not outside diameter
What is the main method for joining small diameter pipe?
Threading
What limits the threading for various refrigerants and pipe sizes?
ASME Standard B31.5, Refrigeration Piping
Pipe with a wall thickness —BLANK— than —BLANK— should not be threaded.
Less, standard weight
What fittings can be used for large pipe and all piping materials?
Flange fittings
What fittings are commonly used to connect to equipment, valves, and wherever it may be necessary to open the joint to permit service or replacement of components?
Flange fittings
For steel pipe, flanges are available in a pressure rating to —BLANK—
2,500 psig
What three tasks are performed when preparing pipe for fabrication?
- Measure the pipe, 2. cut the pipe, 3. thread the pipe
What fabrication tasks will ensure a minimum of improper or defective connections, and ensure there is a minimum leakage and loss of fluid?
- Measure the pipe, 2. cut the pipe, 3. thread the pipe
What are three methods of measuring pipe?
- End-to-center, 2. end-to-end, 3. center-to-center
Which pipe measurement is taken from the center of an elbow or tee screwed on one end to the opposite end of the pipe?
End-to-center
Which pipe measurement is made by first tightening an elbow on the threaded end of a pipe?
End-to-center
Which pipe measurement is made without any fittings?
End-to-end
What measurements are usually shown on pipe drawings?
Center-to-center
Which pipe measurement is the distance between the centers of two fittings in a line of pipe?
Center-to-center
What is the first thing you do when making a center-to-center measurement?
put a fitting on the end of the pipe
To cut a pipe with a pipe cutter, first open the jaws of the cutter by turning the handle —BLANK—
Counterclockwise
After the wheels contact the pipe on a pipe cutter, rotate the handle —BLANK—
one-fourth of a turn in a clockwise direction
When using a pipe cutter, what puts a “bite” on the pipe causing a groove in the pipe when the cutter is rotated?
rotating the handle one-fourth of a turn in a clockwise direction
When using a pipe cutter, what happens if you do not rotate the pipe cutter one turn to make a complete cutting mark around the pipe before turning the handle clockwise to make the cut deeper?
The pipe cutter will make spiral marks around the pipe instead of making on complete circle
What happens if you do not remove the burr from a threaded pipe?
The burr hinders the flow of liquids or gases in the pipe
What is used to remove a burr from the end of a threaded pipe?
A pipe reamer
What are two methods of threading pipe?
Hand and power threading
How many threads should be made on pipe with a size of 1/8 inch
27 Threads per inch
How many threads should be made on pipe with a size of 1/8 inch
27 Threads per inch
How many threads should be made on pipe with a size of 1/4 to 3/8 inch
18 Threads per inch
How many threads should be made on pipe with a size of 1/2 to 3/4 inch
14 Threads per inch
How many threads should be made on pipe with a size of 1 to 2 inches
11.5 threads per inch
How many threads should be made on pipe with a size of 2.5 to 12 inches
8 threads per inch
When using a power threader, how far do you insert the pipe into the chuck?
so it protrudes about 8 inches beyond the face of the chuck
What are two important factors of pipe fabrication?
- Assembly of threaded joints, 2. Pipe expansion and flexibility
During pipe fabrication, what must be done to attain ample flexibility to accommodate thermal and other movements?
Disigning pipe bends and loops or using supplemental devices such as expansion joints
What can happen if you fail to design piping to accommodate thermal and other movements?
- Failure of pipe and support from over-stress and fatigue, 2. Joint leakage, 3. Detrimental forces and stresses in connected equipment.
Copper tubing may be —BLANK—
Hard drawn or annealed
Which copper pipe comes in 20 foot lengths?
hard drawn copper pipe
Which tubing is soft-tempered and comes in rolls?
Annealed copper tubing
For refrigeration systems, how is tubing size measured?
using outside diameter (OD)
What is the difference between plumbing tubing application sizing and refrigeration sizing?
plumbing uses Inside diameter, while refrigeration uses outside diameter
How are heating tubing applications sized?
The same as plumbing, using inside diameter (ID) - AKA “nominal-size tubing”
What types of tubing are mostly used on waterlines?
nominal-sized tubing - K and L
Outside diameter tubing is normally how much bigger than plumbing tubing?
1/8 inch
7/8 inch outside diameter (OD) tubing for refrigeration is equal to what Inside Diameter (ID) for plumbing?
3/4 inch
What are the three types of copper tubing mostly used in HVAC/R?
- K, 2. L, and 3. ACR
What is used to identify K type copper pipe?
A green-colored band and a stencil on the surface
Which copper pipe has the thickest wall?
K type
Which copper is mostly hard drawn but can be soft temper?
K type
What is used to identify L type copper pipe?
A blue-colored band and a stencil on the surface
Which copper is used for recirculating water, refrigerant, and potable water inside buildings?
L Type
How can L copper be purchased?
20 feet hard drawn or 25 to 100 feat annealed (soft) coils
What is on ACR tubing when it is purchased or new?
Plugs on the ends
What do the plugs on the ends of ACR tubing indicate?
That the tubing has been dried and charged with nitrogen from the factory
What is the purpose of the plugs (or seals) on the ends of new ACR tubing?
to reduce oxidation within the tube
What type of stainless steel tubing is mostly used in the refrigeration trade?
low-carbon, nickel, and chromium stainless steel
Why is aluminum being used in refrigeration systems?
because it is lightweight and has a high heat conductivity rating
Why is aluminum being used in refrigeration systems?
because it is lightweight and has a high heat conductivity rating
What fittings are used when an item needs to be readily replaced or the system needs to be leak-free?
Flare
What fittings are used when an item needs to be readily replaced or the system needs to be leak-free?
Flare
What fitting is used when you need a permanent connection (or fix)?
Sweat (or solder) fitting
What fitting is used when you need a permanent connection (or fix)?
Sweat (or solder) fitting
What are the two basic types of tube benders?
- Bending springs, 2. Lever type
What are the two basic types of tube benders?
- Bending springs, 2. Lever type
Which tubing bender can be used when you don’t need a high degree of accuracy?
Bending spring
Which tubing bender can be used when you don’t need a high degree of accuracy?
Bending spring
Which tool is used to make tubing bends when a high degree of accuracy is required?
Lever-type bender
Which tool is used to make tubing bends when a high degree of accuracy is required?
Lever-type bender
