Unit D: Compressed Air Self Test Questions Flashcards
What is the standardized pressure for the SCFM (standard cubic feet per min) performance indicator used in the compressed air industry?
SCFM is standardized using 14.7 psi (103 kPag)
What best describes the piston configuration in a multi-stage air compressor?
Different sizes / assembled in series
What type of air compressor uses both sides of the piston to compress the air?
Double acting
Within a two-stage air compressor, what device is used to cool the air as the air moves from the first stage to the second stage?
Intercooler
What type of compressor develops pressure through the oscillations of a flexible disk?
Reciprocating diaphragm
What type of compressor is used when contamination is not allowed in the discharge air stream?
Reciprocating diaphragm
What type of compressor uses two spinning rotors to trap and compress the air?
Rotary helical screw
What type of compressor uses two spiral elements to trap / compress the air?
Rotary scroll
Which filter installed as part of a compressed air system is considered the most important?
Intake air filter
Where would a water separator be installed in relation to the aftercooler in a compressed air system?
Downstream of the aftercooler
Where would an aftercooler be installed in relation to the compressor in a compressed air system?
Downstream of the compressor
What two methods are used to reject the heat absorbed by the aftercooler?
Air cooling and water cooling
What effect does an intercooler have on compressor performance?
It improves compressor efficiency
What is the disadvantage of an undersized receiver tank?
It causes excessive compressor cycling
What is the disadvantage of an oversized receiver tank?
It wastes energy because the compressor has to run longer
What material absorbs the water vapour from the compressed air inside a deliquescent air dryer?
Salt tablets
Why is a double - wall heat exchanger used when recovering heat used for domestic water heating from an air compressor?
It provides additional protection from contamination
A straight line piping configuration has limitations when providing proper downstream pressure and flow rates. When considering equipment locations, what strategy will minimize these shortcomings?
Place the equipment with high flow requirements near the compressor
What compressor should be considered to provide optimal performance?
Closed - looped networks
What network provides the worst performance?
Octopus networks
What is the name given to a moisture drain trap used in industry that eliminates the loss of system air during the draining process?
Zero - loss drains
What are the 3 main technologies that manufacturers of compressed air drains use in their product lines?
1) pneumatic - mechanical drains
2) Electronic demand drains
3) Series timed electronic drains
What damage could result if an FRL is installed backwards?
The oil from the lubricator could cause other components to plug / become inoperable
Which safety device found on compressed air systems has an engineered “weak spot” that will fail at a predetermined pressure?
Bursting disk
Which safety device found on compressed air systems is used to protect against high discharge air temperatures?
Fusible plug
Which of the following safety devices found on compressed air systems will reset once the condition has been rectified?
Pressure relief valve
When selecting the size of the supply header in a closed - loop piping configuration, what is the max pressure drop that should be allowed in the header?
2 psi (14 kPa)
Approximately how much heat energy would be generated by a 20 HP air compressor?
50 000BTU/hr
Work Safe BC Regulation allows for blowing dusts or other substances from clothing being worn by workers in specially designated areas. What type of PPR must be worn by the workers?
Eye protection and air respirators
What is the max supply pressure of the compressed air allowed by the regulations (when using the air compressor to clean self off)
70 kPa (10psig)
Moisture drains that are subject to freezing should be protected by either of what 2 methods?
1) Insulation
2) Heat tracing
What device should be installed when connecting a compressor to a rigid distribution piping system?
High temp - rated steel braided, vibration isolation flex hose
What device is installed in a pneumatic hose to prevent flow when the air velocity becomes excessive due to hose failure?
Velocity fuse
What type of device is used to provide ease of use when connecting pneumatic tools to a compressed air hose?
A quick disconnecting coupling
Where should the branch take - offs be connected when piping the main air discharge header from the receiver?
Off the top of the main
Automatic drain traps should be installed in which of the following locations?
1) at the bottom of the air receiver
2) at the bottom of drip legs
3) at low points in the system
What is the main limitation in using black iron pipe as a compressed air piping material?
Possibly of corrosion when exposed to condensate
What is the main limitation is using PVC or CPVC as a compressed air piping material?
Possibility the material may shatter when pressurized
What is the recommended joining method when using copper as a compressed air piping material?
95 - 5 soldered or brazed connections
Which leak detection method is considered the compressed air industry standard?
Ultrasonic testing
When testing for leaks in a compressed air system, where are the leaks frequently found?
The last 9 m (30 ft) of piping before the point of use.
In a poorly maintained industrial compressed air system, what percentage of a compressor’s output could be lost from air leaks?
20 - 30%
What advantages are there to reducing the system air pressure to a full - load setting just above the max system requirements?
- Cost savings
- Improved system performance
- reduced leakage rates
- reduced stress on system components
What problem could occur when reducing the system air pressure to a full - load setting just below the min system requirement?
Equipment malfunction
What air quality parameters are not measured?
Discharge temperature
What are 2 advantages to servicing compressed air equipment more frequently than recommended by the manufacturer?
Higher efficiency and economic gains
What 2 adverse effects are present when the compressor air intake filter is not maintained regularly?
Reduced capacity and reduced efficiency
What is the most often ignored component of a compressed air system when it comes to proper maintenance?
The condensate drains
Which type of condensate drain is most prone to air leakage due to neglect?
Manual drains
How many cleanings should a filter undergo before it is replaced?
2 or 3
What is the common cause of most refrigerated air dryer problems?
A clogged condenser
What is the max acceptable range of pressure drop across a pre-filter cartridge serving a desiccant air dryer before it must be replaced?
8 - 10 psi (56 - 70 kPa)
What is the term given to a desiccant material when it is exposed to excessive air flow through a dryer?
Dusting
What device is installed between the pneumatic tool and a quick - disconnect coupling to minimize the effect of vibration or chock from equipment?
a 30 cm (2 ft) whip hose
If a quick disconnect coupling is of a full port design, what does this imply?
The internal orifice is the same size as the pipe size and does not have a ball or a spring
When testing for leaking in a compressed air system, where are the leaks frequently found?
The last 9m (30 ft) of piping before the point of use
In a poorly maintained industrial compressed air system, what % of a compressor’s output could be lost from air leaks?
20 - 30%
Which leak detection method is considered the compressed air industry standard?
Ultrasonic testing
