UNIT 4 Flashcards
MATCH THE TYPE OF EXTINGUISHER WITH THE TYPE OF MATERIAL IT IS DESIGNED TO EXTINGUISH.
Fires in combustible metals, titanium, zirconium, sodium, lithium, and potassium
Class D fires
Fires and flammable liquids, combustible liquids, petroleum, greases, tars oils, oil, based paints solvents, lacquers, alcohols, and flammable gases
Class B fires
Fires that involve energized electrical equipment
Class C fires
Fires in ordinary combustible materials, such as wood cloth, paper, rubber, and many plastics
Class A fires
Fires and cooking appliances that involve combustible cooking media (vegetable or animal oil and fats)
Class K fires
An R-22 cylinder is in a truck with a temperature of 120°F. What would the pressure be in the cylinder?
259.9 PSIG
The cylinder of R-22 above in #6 has an internal surface area of 1500 in.². What is the total outward force of the refrigerant against the inner wall of the cylinder in tons of pressure?
1500 in.² times 259.9 PSIG= 389,850/2000= 194.925 Tons
When it is necessary to perform electrical work in an area that has a damp or wet floor, what safety precautions can be taken to minimize the chance of electrical shock?
- Use only the proper piece of test instrumentation, and make certain that they are in good working condition.
- Where heavy shoes with insulating sole heel.
In what circumstance would an individual get frostbite when working in the refrigeration trade?
-if a person is careless, and the refrigerant gets on a persons, skin or eyes, it will cause frostbite.
How are refrigerant cylinders oriented when in storage or transporting?
-refrigerant cylinders should be stored and transported in the upright position to keep the pressure relief valve in contact with the vapor space.
What precautions must you take if you suspect a compressor has experienced a burnout?
Make sure there is emergency eye and body wash stations readily available due to potential acid in the compressor.
The safety classification for refrigerant is B3. What does that mean?
Highly flammable and toxic
It is 20 feet to the top of the building parapet. What is the minimum length of the extension ladder used and how far from the base of the building should the ladder be positioned?
5 feet from building and 24 feet minimum length. Extension ladders should extend at least 3 feet above the landing surface.
Horizontal distance should be 1/4 the working length of the ladder which would be 5 feet or 5.25 feet using Pythagorean theorem.
What are the symptoms of heat exhaustion?
- Feeling faint or dizzy
- Excessive sweating
- skin is cool, pale and clammy
Current flow of……..A or less through the body can be fatal
0.015A
Customer says that every time the air conditioner is turned on, the 3A fuse in the low-voltage control circuit pops. You suspect the contactor in the outdoor unit is the problem, So you disconnect power to the outdoor unit and disconnect the low-voltage wires attached to the contactor. you set your meter to resistance and check the contactor coil. your meter reads 0.8 ohms. How many amp is the contactor drawing when the contactor is energized with 27 V?
E= I x R————27V= I x 0.8———-I= V/R——I= 27v/0.8ohms= 33.75 amps———-
You have a spare contactor in your truck to replace the bad contactor in number 16 above. before you replace the bad contactor, you check the resistance in the new contactor coil to make sure it will not draw more than 3A or the fuse in the low voltage circuit will blow. What should the resistance of the new contactor coil measure so that the 3A fuse will not blow when the circuit is energized?
I= V/R—-to find resistance, rearrange formula——R= V/I
R= 27/3= 9 ohms (maximum)
Occurs when a person becomes part of the circuit. Can affect the heart and stop it from pumping.
Electric shock
Freezing of body temperature
Frostbite
Moving refrigerant into or out of a refrigeration system via a manifold, gauge recovery machine or vacuum pump
Transferring, refrigerant
Safety device on a pressure vessel or system that are under pressure prevents equipment, damage or rupture of pressure vessels
Relief valve
Fans, Motos or equipment using belts, drives, shafts, or chains that rotate. May cause injury or death if a person interferes with normal operation.
Rotating equipment
Used to move heavy objects. Usually a flatboard with wheels that can move in any direction.
Portable dolly
A refrigeration system consisting of a compressor, evaporator condenser and metering device configured into one casing, much like a window, air conditioning unit, but capable of providing great cooling capacity
Package refrigerant equipment
Threaded metal cylinder with a tapered hole drilled completely through its length. holders filled with a material of low melting point that flows away if a predetermined temperature is reached.
Fusible plug
Made of wood or fiberglass. Used for working around energized equipment and powerlines.
Nonconducting ladder
Plastic case and battery operated tools with motor connections, insulated within the tool
Double insulated power tools
Convert a three prong plug for using a two prong outlet by attaching the third wire to the wall plate. Screw. Will not provide a good ground if screw is attached to an ungrounded box.
3 to 2 prong Adapter
True or false
Single face power means to wire alternating power circuit where one wire is hot and the other wire is neutral or both wires are hot .
True
A properly wired outlet will have a meter reading of______V when test probes are placed in 1 & 3
Zero
A properly wired outlet will have a meter reading of_____V when test probes are placed in plugs, two and three
120 volts
What is the first aid procedure for an individual that has a strong pulse is not sweating. Has a throbbing headache and skin is hot red and dry?
- Call 911 immediately
- If possible, move the individual to a cool place, and use a cool damp rag to apply cool compresses to the skin.
When you must lift a heavy object, use your_________ not your__________ and wear an approved brace if available
Legs, back
What protective equipment is required when recovering or charging a system with refrigerant?
Gloves and protective eyewear
When working on an electrical circuit what positive safety controls should be taken before working on the circuit?
- Don’t wear jewelry
- Whenever possible, the power should be shut off and locked out when servicing equipment
- Ensure your hands only touch your meter probes
- Always work on electric circuits as if they are energized
True or false
Always make three points of contact when using a ladder
True
True or false
A warm coat and gloves should be in your truck even in the middle of summer
True
True or false
A grinding stone made of ferrous metals, such as cast, iron and steel can also be used for non-ferrous metals like copper, aluminum or brass
False
True or false
Fuel and oxygen cylinders can be stored in the same location as long as they are separated by a solid wall 5 feet high
True
Recovery cylinders have yellow bodies and gray tops
False
An oxygen regulator cannot be attached to an acetylene cylinder because the threads don’t match
True
True or false
Acetylene cylinders are not under high-pressure as oxygen and nitrogen cylinders, but still require the use of a pressure regulator
True
Using ohms law as resistance increases, current increases
False
True or false
A fire extinguisher is not required to be nearby, when soldering/brazing
False
True or false
Heat exhaustion is more severe than heat stroke
False
Using a fire extinguisher can best be described by the acronym PASS. What does the acronym stand for?
Pull,l aim, squeeze, sweep
When starting an open motor, what precautions should be taken?
-Never wear loose clothing
-Never attempt to stop a motor by gripping the belt
- All set screws/holding mechanisms must be tight before starting a motor
True or false
Recovery devices should not be used on equipment containing hydrogen
True
In a refrigeration system, air causes__________ discharge pressure
Higher
You should never do this, when a system is in a deep vacuum
Walk away, and leave alone
All commercial and industrial process refrigeration, containing more than 50 pounds of refrigerant must be repaired when the annual leak rate reaches__________%
30%
When evacuating a system, what is the minimum number of microns a vacuum pump must pull?
500 microns
According to EPA standards, removing which component is considered a major repair?
Compressor
Which of the following is used to prevent transient liquid, slugs from getting into the compressor?
Accumulator
