Pneumatics, Vacuum, heat exchangers dryer test Flashcards
warmer the air the more moisture it can hold
true
False
True
relative humidity compares the amount of water a sample of air holds to the maximum amount it could hold if fully saturated
true
False
True
if a cubic foot of air has the capacity to hold 11 grains of moisture but has 5 grains of moisture, then it is said to have _______________ % relative humidity
50
45
40
35
45
if the air is cooled past 100 % relative humidty, then condensation will result. this is called the_________
dry air point
specific humidity point
vapour point
dew point
Dew point
water / moisture in a compressed air system needs to be separated and removed by
air receivers
after coolers
dryers
all the above
All of the above
adsorption dryers work on the principle of ________ of molecules in a thin layer onto the desiccant
a chemical bond
vapourization
adheasion
regeneration
Adhesion
the process of removing the accumulation of moisture from the dryer bed is called____________ which uses ________________
regeneration, heat
regeneration, absoption
regeneration, purge gas
both the 1st and 3rd answer are correct
Both first and third
about __________% of dry air is used for regeneration in heater-less dryers
10-15
20-30
40-60
1-2
10-15
the ideal system for adsobtion dryers is a twin tower system with ___________ which reduces the amount of cycle times and compressed air usage
cams and mechanical valves
electronic switches and automatic valves activated by the dew point sensor in the system
electronic switches and automatic valves
none of the above
Electric switches and automatic valves activate by the dewpoint sensor in the system
because desiccant can break down of become contaminated with oil, the air drying system needs to be protected with coalescing filters
true
False
True
in the regeneration cycle, the purge air is _____________ to help reduce compaction and make removal of moisture faster
sped up
deflected
reversed
cooled
Reversed
.a heated adsorption dryer with internal heaters uses about______% of the dryed air.
2
5
10
12
2
the moist gas from the regeneration cycle (purge gas) in not explosive or hazardous, then it can be vented to the atmosphere. otherwise it has to be cooled and ran thru a moisture separator and re-introduced to the dryer inlet gas stream
true
false
True
the rotary drum dryer has 2 separate air flows going thru it. the hot dry gas passes thru____ % of the rotor and the moist gas passes thru ______ % of the rotor
50, 50
75, 25
25, 75
60, 40
25,75
absorption dryers use __________ in the process to dry the air
adheasion
vaporization
chemical bond
all the above
Chemical bond
chemical dryers cannot be regenerated because they dissolve or melt when combined with moisture
true
false
True
in the liquid dehydration process, an absorption agent such as ethylene glycol is sprayed thru nozzles and as the air travels down thru it, it is scrubbed and moisture absorbed
true
False
False
to remove the moisture from the glycol, it is ran thru a ______________where it is heated to 200 C and moisture is evaporated
heat exchanger
vapourizer
steam cleaner
still
Still
refrigeration dryers use the dew point reduction method to remove moisture from the air thru the use of an air circuit and a refrigeration cycle
true
False
True
latent heat is heat that is sensed by a thermometer
true
False
False
in mechanical dryers, water sprayers are added to cool down the air before it strikes the baffles that create a torturous path
true
false
False
colescing filter elements can effectively remove particles down to a size of _________ microns
0.001
0.0001
0.01
0.1
.01
the best way to determine if a dryer is taking out moisture, is to
check the dessicant
watch the cycle times
measure the flow rates
measure the dew point of the air
Measure the dew point
wire drawing is
used to seal flanges
process of air movement thru the dessicant
a fine groove cut in a sealing surface (caused by high pressure gas)
none of the above
A fine groove cut in a sealing surface (caused by high pressure gas)
most dryers that run below 175 degrees C, use a teflon valve seat
true
False
True
in a pneumatic system, the compressor intake should be in a __________ place because the air is denser
wet
cool
hot
Cool
when compressing with a reciprocating compressor, you need a _____________ to help dampen pulsations
after-cooler
minimum of bends in the intake
inter-cooler
receiver
Receiver
the pneumantic piping system that has the compressor close to its point of use is the
grid
decentralized
loop
none of the above
Decentralized
proper sizing of lines in a pneumatic system is important because if the piping is to small, it will
cause moisture in the air supply
cool the air supply
cause a pressure drop in the air supply
create more flow
Cause a pressure drop in the air supply
you must eliminate all leaks in a compressed air system because it will cost more to produce the needed CFM
true
False
True
if an FRL is installed backwards, it would
gum up the regulator with oil
remove lubrication
work normally
the 1st and 2nd answers are correct
Both first and second answers
in an FRL, the filter uses ___________ and the lubricator uses ________ to work properly
centrifugal force, venturi
venturi, centrifugal force
none of the above
regeneration, desiccant
Centrifugal force, venturi
water traps use a _________ to expel moisture automatically from the unit
pressure drop
deflector plate
float valve
hand valve
Float valve
a 5/3 valve has ________ and ____________ positions
3 ways, 5
5 ways, 3
5 ports, 3
both the 2nd and 3rd answers are correct
Both second and third answers are correct
a pressure reducing valve has a normally _____________flow path thru it
closed
open
both open and closed
none of the above
Open
venting regulators will protect the _______________ from over pressure
upstream section
downstream section
does not protect any part of the system
vent to the receiver
Downstream section