Module K (160301) Flashcards
__________________ involves the compression of gases to raise pressure, which is then put to work when the gas is allowed to expand in a controlled manner.
Pneumatics
Air receivers are pressure vessels and, as such, come under the applicable codes enforced under the __________________
Alberta Boiler and Pressure Vessels Act
What is the purpose of cyclone separators and dryers?
They dispose of moisture in pneumatic system lines to prevent problems
What are the three piping systems?
- Grid
- Decentralized
- Loop
Which is the simplest piping system?
Grid
Which piping system is also known as a dead end system?
Grid
The pros of a grid systems are that they are simple and cheap. What are the cons of this system?
Because there is only one flow path for the air, workstations at the end of the system may experience air starvation.
What is the downside of using oversized compoents?
Though oversized components increase efficiency, they cost more to install
The ________________ problem is alleviated by a line sloping towards a water leg and the drop taken off the top of the main line.
mositure
The FRL unit must be installed in the air line in the correct position to prevent ___________________
contamination damage
What is the correct order to install an FRL unit?
- The filter vto clean the air and protect downstream components (like regulator)
- The regulator to maintain a set system pressure
- The lubricator to add a mist of oil to the air stream
What happens when an FRL is installed backwards?
The oil from the lubricator would gum up the regulator and then the filter would remove any oil left in the air before it got to its point of use
The ____________ around the filter keeps the swirling air from affecting the operation of the filter
Shroud
The __________ below the filter prevents the contaminants and moisture from becoming airborne again
baffle
What would happen if the spring in a regulator broke?
the valve will shut off
A piece of white cardboard placed near the ________________ of the component should give a pale yellow indication of oil.
exhaust port
What does dripping oil from the exhaust port mean?
the lubricator needs to be adjusted
Which motors are used in equipment due to their low weight and compact size?
Vane motor
What are some examples of equipment which uses a vane motor?
impact guns, grinders, and drills
What is the most common flow control valve for smaller pneumatic actuators?
needle valve
What is the most common flow control valve for larger pneumatic sysmetms?
ball and globe valves
What is the difference between venting regulators and non-venting regulators?
Venting regulators also act as relief valves for the downstream section of the circuit to prevent any possibility of an increase in pressure in this section
How does pressure affect the amount of moisture in the air?
The increase in pressure tends to reduce the amount of moisture the air can carry.
How does an increase in temperature affect affect the amount of moisture in the air?
Increased temperature will lead to an increase in moisture in the air
The best way to determine a dryer’s condition is measurement of ______________
dew point
How can you measure a dryer’s dew point?
With a sensor called a dew point hygrometer
________________ is the only mechanical means of drying air that suppresses or lowers the dew point
over-compression
What is over-compression?
the mechanical means of drying air which can lower the dew point
Centrifugal separators are sometimes called _______________ separators
cyclonic
Where are centrifugal separators located?
downstream of compressor aftercoolers or wherever excess moisture needs to be removed
_______________ is heat that is added or removed and cannot be sensed by a thermometer
latent heat
What is a British Thermal Unit (BTU)?
The amount of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit.
How many BTUs does it take to raise 1 pound of water by 1*F?
One BTU
How many BTUs does it take to vaporize one pound of water?
970 BTU
What is a calorie?
The heat energy required to raise 1 gram of water by 1*C at atmospheric pressure
______________________ are the least expensive method of dew point reduction from both operational and maintance perspectives
refrigeration dryers
What is bead-type modified silica gel?
similar to silica gel, but spherical in shape. This gel is very porous
How is the correct dryer size chosen?
By ensuing dryers provide the correct velocities so that the air passing through the desiccant spends adequate time in contact with it to ensure proper moisture removal.
What is the benefit of a system that measures the dew point of the air leaving the dryer?
Since it prevents switching to regeneration cycle until the air exiting is not in acceptable limits, there is:
1. reduced wear of moving parts in valves
2. increased desiccant life
______________ dryers can achieve lower dew points than any other types of dryer
adsorption
What is regeneration?
A term used for the process of removing the accumulation of moisture from the dryer bed
What are some examples of mechanical dryers?
- liquid separators
- centrifugal separators
- demister pads
- over-compression
- coalescing filters
What is a mechanical dryer?
A device that uses a mechanical or physical means to cause moisture to fall out of the air stream such as barriers and filters.
What is the difference between the packed bore design and the packed spool design?
Packed bore: the o-rings are fixed in grooves in the body through which the spool slides
Packed spool: the o-rings are fixed in the spool
What is a FRL unit?
filter regulator lubricator unit
fog lubricators serve best when the flow to the component is _________ and _______
straight and short
mist lubricators serve best when the oil must be ____________________________
carried for long distances, so that the oil will not settle in the line
To function correctly, many ________components require lubrication
pneumatic
____________________ supply clean oil into the line to be carried to the components
air lubricators
Where must the air lubricator be located?
downstream from any device that might be contaminated by lubricating oil (such as paint sprayers)
A ______________ swirls the air around the filter bowl
deflector
Air dryers can lower the dew point to as low as ________
-40C or -40F
Deliquescent dryers contain ______________________.
chemical dessicants
What happens to the chemical desiccants that absorb moisture in a deliquescent dryer?
they are consumed
The safety valve is usually set _____% above the system’s maximum pressure.
5% to 10%
What is the usual maximum working air pressure?
690 kPa (100psi)
What is the purpose of a safety valve?
to release any excessive pressure due to the failure of the unloading valve or a pressure surge
The air receiver is built to specific standards. Safe operation requires that the receiver is equipped with which four items for safety?
- Relief or safety valve
- Drain valve
- Fusible plug
- Air pressure gauge
When do aftercoolers cool the air?
Heat exchangers cool the air after it leaves the compressor and before it enters the receiver.
Which component can also act as an aftercooler?
a receiver
Where is a water trap installed?
Wherever the compressed air is cooled and may fall below its dew point.
The amount of air slip in all screw compressors can be reduced by increasing _____________________
the rpm of the rotors
What is the maximum continuous vacuum rating of a rotary vane (multi-stage) vacuum pump?
29.5 “Hg
Under atmospheric pressure at sea level, pressure gauges read ______
zero (0 psig)
How can you calculate the psia value?
Add 14.7 to psig
Absolute zero, the temperature where no molecular movement occurs is equal to ______C and ______F
-273C and -459F
What is the pressure rating at absolute zero?
0 psia
What is the pressure rating at sea level, under normal conditions of temperature?
14.7 psia
