UTA7 Compressed Air Systems Flashcards
What discuss general considerations of planning, estimating, and scheduling of projects? (Page 7-1)
NAVFAC P-405
Generally, you can make changes to the schedule within how many days of crew arrival on the job? (Page 7-2)
45
The underground water service and the building drain or sewer should not be less than how many feet apart horizontally and placed on undisturbed or compacted earth? (Page 7-2)
6
Piping with a diameter of 3 inches or less requires a slope of not less than what size per foot? (Page 7-3)
1/4 inch
The building drain in a sanitary system must be of sufficient size to carry off all the water and waste materials that may be discharged into it at any one time. The minimum allowable size is how many inches for cast-iron pipe? (Page 7-4)
3
What term is used for the vertical line of soil or waste piping into which the soil or waste branches carry the discharge from fixtures to the house drain? (Page 7-5)
Stack
A waste stack carries liquid wastes that do not contain human excrement; what carries liquid wastes that do? (Page 7-5)
Soil stack
An offset in a vertical stack with a change in direction of how many degrees or less from the vertical piping may be sized as a straight vertical stack? (Page 7-6)
45
In piping where a horizontal branch connects to the stack within how many feet above or below the offset, a relief vent should be installed? (Page 7-6)
2
Size of waste pipe should be at least 1 1/2 inches for wall- mounted urinals and how many inches for the pedestal siphon jet urinal? (Page 7-6)
3
hen a sink is equipped with a garbage disposal unit, a minimum of how many inches is required for the cast-iron or steel drainage piping? (Page 7-6)
2
Building storm drains should generally be graded at least what size per foot whenever feasible? (Page 7-9)
1/4 inch
The stream of water in a pipe is made up of a series of layers moving at different speeds with the center layer moving the fastest. The resistance to flow is called what and causes a drop in pressure of the water flowing through the pipe? (Page 7-11)
Pipe friction
Localized corrosion is caused by the electrolytic action of a what? (Page 7-20)
Galvanic cell
What is a selective type of corrosion that occurs in copper and zinc alloys? (Page 7-22)
Dezincification
What is a peculiar form of disintegration that attacks grey cast iron? (Page 7-22)
Graphitization
What is a term applied to metal that becomes brittle because of the action of some form of corrosion that causes the formation of hydrogen on its surface? (Page 7-22)
Hydrogen embrittlement
What are materials that will not conduct electricity? (Page 7-22)
Nonelectrolytes
Hydrogen sulfide causes scaling of iron at temperatures from1400° to what? (Page 7-22)
2000°F
High-carbon steels are attacked by hydrogen at temperatures above what? (Page 7-22)
750°F
What is any substance that conducts electricity? (Page 7-23)
Electrolyte
What type of base coatings are the most common type of protective coatings used? (Page 7-24)
Asphalt
Some of the most important paint coatings are coal tar, asphalt, rubber, and what else? (Page 7-24)
Vinyl
What paints have the outstanding characteristics of low permeability and resistance to electrolytic reaction? (Page 7-24)
Coal tar
What paints are weather resistant and durable against industrial fumes, condensation, and sunlight action? (Page 7-24)
Asphalt
What paints are very resistant to acids, alkalies, salts, alcohols, petroleum products, and inorganic oils? (Page 7-24)
Rubber base
What paints dry to a film that is tough, abrasion proof, and highly resistant to electrolysis? (Page 7-24)
Vinyl
Well mixed concrete, usually a mix of one part portland cement to two parts sand, may be applied to pipelines. The thickness of the coating applied may be up to how many inches? (Page 7-25)
2
Metals such as iron cor- rode rapidly when used in high- temperature equip- ment because at a critical temperature of approximately what, iron becomes anodic to zinc? (Page 7-25)
140°F
Galvanic cathodic protection is a means of reducing or preventing the corrosion of a metal surface by the use of sacrificial anodes or what else? (Page 7-25)
Impressed currents
The galvanic anode method of cathodic protection uses an electrode referred to as what type of anode that corrodes to protect a structure? (Page 7-25)
Sacrificial
What method of cathodic protection is designed to protect large metal structures located in corrosive areas? (Page 7-26)
Impressed current
What is a recording instrument designed with a chart that makes one revolution in 24 hours? (Page 7-26)
Volt millivoltmeter
What measuring instruments are units used to test the corrosive action of a soil? (Page 7-27)
Resistivity
A protective coating leak detector (referred to as a what) is used to detect the in pipe coatings? (Page 7-27)
Holiday detector
Anode life varies from 5 to how many years, depending upon the type of anode used? (Page 7-28)
30
The materials most often used for anodes with impressed current are aluminum, high-silicon cast iron, and what else? (Page 7-28)
Graphite
Scrap iron and steel may be used for anodes since they waste away at a rate of how many pounds per ampere year? (Page 7-28)
20
Low-pressure systems provide compressed air at a maximum of how many pounds per square inch gauge (psig)
125 psig
Medium-pressure systems provide compressed air from 126 psig to what maximum pressure?
126 - 399 psig
High-pressure systems provide compressed air within what pressure range?
400 - 6,000 psig
What type of shop or laboratory requires up to 6,000 psig of compressed air?
Testing laboratory
Of the following grades of commercial compressed air, which one is the most pure?
Grade A
A refrigerant dryer with a dew point at what maximum temperature should be used to remove moisture to meet air quality requirements for instrument and control air?
30°F
With pressure in excess of 400 psig, oil causes what compression phenomenon to occur?
Compression combustion
In a reciprocating compressor, what are the three compression cycle phases?
Intake
Compression
Discharge
n a W-type compressor, there are a total of how many cylinders in the (a) first and (b) second stages?
Two cylinders for the 1st stage
What type of compressor has two mating rotating screws, one locked and one grooved, to provide the driving force?
Helical screw compressors
When the load is reasonably constant, what type of compressor is intended for near-continuous industrial air service?
Centrifugal compressor
When placed through a parapet roof, you should extend air intakes what approximate distance above the roof?
8 to 10 feet
Of the following types of intake filters, which one(s) is/are best suited for use in locations where dust is prevalent in the atmosphere?
Oil bath and viscous impingement
The intercooler in a multistage compressor serves what purpose?
To reduce the temperature of compressed air between each stage
Aftercoolers are used in compressor discharge lines for which reason(s)?
To lower the air discharge temperature and facilitate condensation and
removal of moisture
Separators are used in conjunction with aftercoolers for what purpose?
To remove water and oil from the compressed air
Compressor cylinder oil should have what minimum flash-point temperature?
350°F minimum
Pulsation dampeners serve as pulsation and noise mufflers due to what feature within the dampener?
An acoustical chamber
The inlet valve unloading device functions mechanically to remove compression loads from the prime mover by _________.
holding the inlet valve open during the suction and compression strokes.
The volume of air that can be released from a compressor cylinder into one clearance pocket is equal to what percentage of the cylinder volume?
25%
or
1/4
When sizing a motor, you should take which of the following factors into consideration?
Belt or drive losses of power
Belt selection for a large motor should be based on what ideal percentage of motor size?
125%
150% preferred
What type of air distribution system is used for isolated service or in situations where special requirements dictate a single path?
Radial, one-way
What type of closed-route air distribution system can be used throughout a building?
Loop system
Normally, a compressed air distribution system is sized by calculating what factor?
Friction loss
In situations where compressed air pipes are pitched upward causing condensate to flow against the flow of air, the minimum pitch of how many inches per hundred feet should be allowed?
6”
When testing a system with dry air or nitrogen, you should use what percentage of maximum working pressure for a minimum of 4 hours?
150%
What maintenance program prevents most major prime-mover breakdowns?
Daily operator maintenance
When a manufacturer’s recommended tolerance level between two moving parts is exceeded on a compressor, you must perform which, if any, of the following actions?
A component adjustment or an equipment overhaul
Air filters should be checked and cleaned a minimum of how often?
Once a month
Low-pressure compressed air systems provide compressed air up to what psig pressure? (Page 11-2)
125
Medium-pressure systems provide compressed air within the range of 126 to what psig pressure? (Page 11-2)
399
High-pressure compressed air systems provide compressed air within the range of 400 to how many psig pressure? (Page 11-2)
6,000
Particulate are sized in microns or what else? (Page 11-2)
Micrometers
Particles larger than how many microns are visual to the naked eye? (Page 11-2)
10
Commercial compressed air is graded according to its purity. The purest is grade A running alphabetically to what grade which is the least pure? (Page 11-3)
J
What Federal Specification outlines the specific requirements for breathing air? (Page 11-3)
BB-A-1034
There are basically two types of compressors: positive displacement and what else? (Page 11-5)
Dynamic
Compressors that provide a discharge pressure above what psi are classified as high pressure? (Page 11-5)
1,000
What type of compressors are high-speed rotating machines in which air is compressed by the action of rotating impellers or blades that impart velocity and pressure to the air? (Page 11-8)
Dynamic
Centrifugal compressors have a lower limit of stable operation called the what? (Page 11-8)
Surge point
Whenever air intakes must be placed through a roof that is surrounded by parapets, they should be how many feet above the roof? (Page 11-8)
8 to 10
What are similar to mufflers and function simply to eliminate objectionable compressor suction noise? (Page 11-11)
Silencers
When air is compressed to 100 psi without heat loss, the final temperature is about what? (Page 11-12)
485°F
What are installed in compressor discharge lines to lower the air discharge temperature, thus condensing the moisture and allowing it to be removed? (Page 11-12)
Aftercoolers
High compressor discharge temperatures require lubrication flows and characteristics that still lubricate when subjected to what temperature or higher discharge air temperature conditions? (Page 11-16)
300°F
Prime movers for compressors can be electrical, gasoline, or what else? (Page 11-20)
Diesel driven
Induction motors can be used to power single- acting reciprocating compressors ranging from fractional horsepower up to approximately 300 horsepower at a speed of how many rpm? (Page 11-21)
1,800
After installation, the compressed air system must undergo testing. Generally, all piping andpressurized components should be tested at 150 percent of maximum working pressure. When testing, use clean, dry air or nitrogen. The system should be held at test pressure without loss for at least how many hours? (Page 11-26)
4
All auxiliary equipment that services the air compressor or is serviced by the compressor requires periodic scheduled maintenance. Air filters should be checked and cleaned at least how often? (Page 11-27)
Monthly
