UTA10 AC/R Flashcards
What is the wastewater of community life? (Page 10-1)
Sewage
The major sources of raw sewage are domestic sewage, industrial sewage, and what else? (Page 10-1)
Storm water
Heavy input of storm water can disturb the opera- tion of a treatment plant by sending it too much water, a problem called what? (Page 10-2)
Hydraulic overloading
The color of wastewater containing dissolved oxygen (DO) is normally what color? (Page 10-3)
Gray
Black-colored wastewater usually accompanied by foul odors, containing little or no DO, is said to be what? (Page 10-3)
Septic
Those solids that are not dissolved in wastewater are called what? (Page 10-4)
Suspended solids
What term is used to describe the acid or base properties of water solutions? (Page 10-5)
pH
A pH value less than what is acidic? (Page 10-6)
7
What are life-supporting nitrogen and phosphorus? (Page 10-7)
Nutrients
The three biological organisms present in wastewater are bacteria, viruses, and what else? (Page 10-8)
Parasites
What type of bacteria can live with or without dissolved oxygen? (Page 10-8)
Facultative
A grab sample is a single sample of wastewater taken over a short span of time, usually less than how many minutes? (Page 10-8)
15
Pure water at 20°C at sea level can hold a maximum of how many mg/l of DO? (Page 10-15)
9.17
What test is often used with all kinds of activated sludge plants to find the amount of solids in aeration units? (Page 10-22)
Settleability
What test is the most important test for finding the polluting strength of a wastewater? (Page 10-22)
5 Day Biochemical Oxygen Demand test
BOD5
Influent wastewater may have as much as how many mg/l of suspended solids? (Page 10-23)
400
What test is an indicator of harmful bacteria in the wastewater? (Page 10-23)
Fecal coliform
A report is required for all wastewater plants on a military installation how often? (Page 10-24)
Monthly
All plants that discharge an effluent must have NPDES permits issued by the what? (Page 10-27)
EPA
The minimum acceptable size of septic tank is how many gallons? (Page 10-32)
1,000
The physical location of a septic tank in relation to wells must be no closer than 100 feet from a shallow well and no closer than how many feet from a deep well? (Page 10-34)
50
What are usually dry-laid masonry or brick-lined wells without any masonry at the bottom? (Page 10-34)
Cesspools
Leaching cesspools should not be placed closer together than how many feet by out-to-out measurement of walls? (Page 10-36)
20
The lines in a leaching fields are built of how many-inch PVC perforated pipe? (Page 10-37)
4
(True or False) Once the type of air-conditioning system has been chosen, the next step is to figure out its appropriate size.
True
What is the temperature range of the cylinders that store the liquid refrigerant in an expandable evaporator system?
−20°F to −60°F
textbook says 60°F instead of -60°F
(True or False) The compound refrigeration system allows two different refrigerants to be used, and can produce temperatures as low as −50°F.
False
It uses 2 or more compressors with the same refrigerant
AND
It can attain −80°F.
What type of blower evaporator is designed for mounting behind windows and door frames?
Vertical flat-type
What electrical room thermostats are usually 115 volts, are dangerous to the user, and are more expensive?
Line-voltage
(True or False) The three pressures that affect the operation of the TEV are; bulb, evaporator, and spring.
True
What type of single-phase motor has limited starting torque and is usually used with window air conditioners?
Permanent split-phase motor
How many electrical terminals do hermetic motors have that are connected through an insulated seal to the motor windings inside the dome?
3
What are the two basic types of circuits?
Load and control
Which method is used to test windings for grounds?
A. Ohmmeter continuity test
B. Test lamp continuity check
C. Resistance measurement with a megohmmeter
D. All of the above
D. All of the above
(True or False) The first step in performing an ohmmeter continuity test is to disconnect the power and remove the wires from the motor terminals.
True
What type of starting relay is electromagnetic and is used with split-phase induction-run motors?
Current relay
When a starting relay fails, which device can be used to start the compressor motor by bypassing the relay manually?
A test line cord, fuse and capacitor
What type of air-conditioning system should be used when the areas to be air- conditioned are in close proximity to each other?
Forced air units
What type of manifold gauges are needed when working on an ammonia- absorption refrigeration system?
Steel manifold gauges
What type of evaporator system is used to preserve the freshness of fruits, vegetables, meats, and fish?
Spray evaporator systems
What type of refrigeration system has no moving parts?
Thermoelectric refrigeration systems
What maximum temperature can be maintained in a cascade refrigeration system?
−50°F
What maximum temperature can be attained in a three-stage compound refrigeration system?
−135°F
When mounting a condenser on a roof, what consideration is considered the most important?
Roof load strength
What types of metal are used in a bimetal thermostat?
Brass and Invar
What type of thermostat uses 24 volts?
Low-voltage
What is the most commonly used metering device?
Thermal expansion valve (TEV)
Which of the following types of motors should be used for 5-horsepower, high- starting torque requirement?
Capacitor-start, capacitor-run
Which of the following components is considered a load?
Compressor contactor
Which of the following conditions exists in the case of a shorted-winding?
A loop of cooper wire is in contact with another wire
Which of the following devices can be used to test a hermetic motor for grounds? A. Ohmmeter B. Test lamp C. Megger D. All of the above
D. All of the above
Which starting relay is capable of de-energizing the running winding circuit when the circuit draws excessive current?
Thermal Relay
(True or False) When checking relay contacts, voltage and thermal relay contacts are normally open.
False
Their normally closed
When testing a capacitor with an ohmmeter, what general reading on the meter indicates the capacitor is good?
0 or low resistance then climbs to high resistance
What are used when the areas to be air-conditioned are close to each other, are being used for similar purposes, or have the same humidity and comfort zone requirements? (Page 14-1)
Forced air units
There are how many general factors that affect the refrigeration heat-load estimate required for a particular application? (Page 14-3)
Five
An absorption refrigeration system uses either water, ammonia, or what else as the refrigerant? (Page 14-3)
Lithium bromide
What will instantly freeze any part of the human body that it touches? (Page 14-6)
Liquid nitrogen
What system uses two or more compressers connected in series in the same refrigeration system? (Page 14-7)
Compound
A two-stage compound system can attain a temperature of approximately what? (Page 14-9)
–80°F
Electrical room thermostats are in three categories: line voltage, low voltage, and millivoltage. Line-voltage thermostats are usually how many volts? (Page 14-13)
115
The millivoltage thermostat operates at 750, 500, or how many millivolts? (Page 14-12A)
250
One component that enhances the operation of a thermostat is a what? (Page 14-12A)
Anticipator
Basically, there are four types of single-phase motors used in hermetic assemblies: the split- phase; the capacitor-start, induction- run; the capacitor-start, capacitor-run; and the what? (Page 14-16)
Permanent split-phase
There are two basic types of circuits, what are they? (Page 14-19)
Load and control
What is the result of a burned-out or grounded fault or simply a break somewhere in the lead or winding that prevents the current from completing the circuit? (Page 14-18E)
Open winding
What can be used to check windings for shorts? (Page 14-20)
Ohmmeter
What is the result of an electrical conductor in contact, either directly or indirectly, with the motor frame or the metal shell of the unit? (Page 14-20)
Ground
Three methods of testing windings for grounds are the ohmmeter continuity test, the test lamp continuity check, and the resistance measurement with a what? (Page 14-20)
Megohmmeter
Electrical components in hermetic motor compressor circuits that give trouble include starting relays, overload protectors, and what else? (Page 14-21)
Capacitors
What is an electromagnet, similar to a solenoid valve, that employs a weight and spring to hold the contacts open when the circuit is idle? (Page 14-21)
Current relay
What operate on the theory that electrical energy can be turned into heat energy and that, when the temperature of a metal is increased, the metal expands? (Page 14-22)
Thermal relays
What type of capacitor serves to provide a smoother and quieter operating motor? (Page 14-23)
Run
All wiring circuits are built around how many requirements? (Page 14-25)
Four