D1: Install Compressed Air Systems Flashcards
What type of air is compressed air?
Atmospheric air
What is the major use of compressed air?
Spray painting for automotive
What does atmospheric air consist of?
78% nitrogen
21% oxygen
What is air weight called?
Atmospheric pressure
What is the pressure of atmospheric at sea level?
101.3 kPa
14.7 psi
How is compressed air measured?
Of air in its free state or Standard atmospheric condition (SCFM)
What does SCFM stand for?
Standard Cubic Feet / Min
What temperature defines standard air?
20C (68F)
What happens to atmospheric pressure and density of air as altitude increases?
They both decrease
Would less air or more air have to be delivered by the compressor at higher elevation?
A smaller output quantity would be delivered
Air delivery of a compressor is reduced how much for every 1000 feet in elevation?
3%
What happens when temp rises above 20 C?
There will be a loss of air delivery that = 2% for every 5.6 C increase in Room temp
True or False:
Air from the discharge side of a compressor is hot because it has been compressed.
True
Why do we get a false reading on the air pressure gauge with hit air?
Hot air requires more space - when air cools, gauge drops
How do we get a true pressure reading?
By using an Aftercooler
What are 2 subsystems of compressed air?
1) supply side
2) demand side
How do you describe the supply side of a compressor?
Includes equipment at the source
What is Demand side of a compressor?
Distribution piping
Secondary treatment equipment
End use tool
What is included on the Supply side?
Air intake
Air compressor
Motor and controls
Inter/ aftercooler
Moisture separators
Receivers
Primary tx equipment / accessories
What are 2 basic compressor types?
Reciprocating
Rotart
How does a Reciprocating Single Acting (single stage) compressor work?
Air is drawn in and compressed in a single stroke
How does a Reciprocating single acting (two-Stage) compressor work?
Has a min of 2 cylinders in series
Low pressure cylinder = largest
High pressure cylinder = smallest
As air passes through each cylinder, it requires less space
How does a Reciprocating Double acting compressor work?
Has compression chambers on both sides of a piston
How does a Reciprocating diaphragm work?
develops pressure via reciprocating or oscillating action of a flexible disk
Where are diaphragm compressors most often used?
When no contamination is allowed in the output air line or atmosphere.
- Used mostly for light - duty applications
What is a Rotary Sliding vane?
Pumping action is produced by a series of sliding, flat vanes as they rotate in a cylindrical housing
What part of the Rotary Sliding vane big and which part small?
Suction = larger = creates a vacuum
Exhaust port = smaller = discharges air
What does a Rotary Screw compressor do?
Uses 2 rotors (helical screws) to compress air
- When they start turning they mesh together / air is drawn in on one side ( suction side) / pushed through to the ends of rotors = pressure side
What is the advantage of a Rotary Screw compressor?
includes a smooth, pulse - free air output
True or False rotary screws can either be oil injected or oil free.
True
What is a Rotary Scroll compressor?
Contains 2 spiral elements
- Moves in eccentric circles while the other element is stationary
How does a Rotary Scroll pull in air?
Air is drawn in bn the 2 spiral elements on the suction side / transported to the centre of the spiral.
- reduced vol at the center = compressed air.
What is a big advantage of the Rotary Scroll compressor?
has a quiet operation
- only has one moving part
- No oil
- maintenance is very easy
What job does an Intercooler have?
Helps cool the air before it is introduced into the next stage for further compression
What are 2 ways intercoolers, cool?
- Air cooling
- Water cooling
How does air cooling work?
Uses fins to increase surface area to help “blow off” heat
How does an Intercooling - water cooling work?
Passes the compressed air through a water - cooled heat exchanger
What is an Aftercooler?
Is a heat exchanger that cools hot compressed air to condense the water vapour (otherwise would condense in the piping system)
True or False: the aftercooler can be either water or air cooled.
True
Where is the aftercooler installed?
After the last stage of compression
80 - 90% of condensate is collected where?
In the aftercooler
What is an Integral aftercooler?
A compressor that comes as a package from the manufacturer
What 2 places are air filters found?
At the air-intake to the air compressor
In the compresses air piping, between the compressor and the end user’s equipment.
What is the most important filter on the compressor?
Intake air filter
What are line filters?
Compressed air filter downstream of the air compressor
What do line filters do?
Remove contaminants (particulates), condesate and lubricant
The finer the filter…
The greater the pressure differential (pressure drop) across the element
What do particulate filters do?
remove solid particles and have the lowest differential.
What are Coalescing filters?
are used to remove lubricant / moisture.
have the highest differential
What are moisture separators?
They are devices that remove entrained liquids from air
Where are moisture separators installed?
following aftercoolers to remove the remaining condensed moisture.
What are the 2 types of moisture separators?
1) Centrifugal (Cyclone)
2) Coalescing
What do Centrifugal Separators?
They direct air at an angle into a cone shaped chamber which creates a spinning vortex
What is a coalescing separator?
Solid objects are captured in the filter cartridge
fluid particles are caught in the filter bowl
What does an oil and water condensate separation system do?
removes all contaminated condensate from the compressed air / separates the oil from the water
What does an air receiver tank act as?
a reservoir
How does an air receiver tank help remove water from the system?
It allows water to cool
What is the generalized sizing guideline for an air receiver tank?
3 - 5 GPM / CFM ( at full load)
True or false: The relief valve should be set to 10% higher than the operating pressure of the system
True
How does an air tank promote moisture separation?
Through receiver piping entering low and exiting high
Where are drains needed?
At all separators, filters, dryers and receivers
When is an air dryer required?
when air is subject to freezing temperatures or where water vapour in the air can be harmful
What are the 4 types of air dryers?
1) Refrigerant
2) Deliquescent dryers
3) Desiccant dryers
4) Membrane air dryers
How does a refrigerant dryer work?
cools the air to lower temps (below the dew point), condensing / collecting much of the water vapour
Can refrigeration dryers be exposed to freezing environments?
No
What is a deliquescent dryer?
a tank full of salt tablets
does not need electricity
water removed is part of a salt brine
What do desiccant dryers do?
they are porous and absorb water vapour molecules
What is a deciccant dryer called regenerative?
because the 2 towers switch their roles constantly
When is a desiccant dryers a good choice?
when there will be exposed to freezing conditions
where instrument quality air is required.
How does air flow through membrane air dryers?
air passes a bundle of hollow membrane tubes and water permeates the membrane walls
What causes the membranes to break down quickly?
the oil and dirt they are susceptible to
When compressed air is giving off heat, how is this heat removed?
by Heat recovery equipment
What job does the Distribution piping have?
links various components of the compressed air system to deliver air to the point - of - use w/ minimal pressure loss
What are the 2 most common piping layouts?
straight line networks
closed loop networks
How do straight line network work?
maintains pressure at the point of use be reducing the size of the central pipe as it moves away from the compressor
What is the problem with a straight line network?
sacrifices flow rate to preserve downstream pressure
Straight line networks often evolve into what?
Octopus networks
What does a close loop network provide?
provides a balance between flow rate and pressure at all points of use in the system
A closed loop network allows the air supply to flow through…
several lines at a time w/ at least 2 different supply routes
Is a secondary receiver a larger or smaller tank?
Smaller - acts as a shock absorber
Where are manual drains used?
At system low points
What kind of valve is a manual drain?
ball or gate valve
Why are manual drains ignored/neglected?
they rely on human interaction
What is zero loss?
When moisture is automatically released w/o the loss of any system air
What is an internal float drain?
Located at end user filter housings
are normally open / normally closed (is the automatic one)
What is a Timed solenoid electric drain? (not a zero loss design)
works with 2 timers
1 - set for intervals
2 - set for amount of time open
What is the Electronic level sensing condensate drain?
Are zero loss design
based on level of demand - only operate when liquid present
What are pneumatic / mechanical drains?
are zero loss design
powered by air
are portable
What is the best kind of drain to go with?
zero loss drains that open automatically
How does SCFM differ from CFM?
S indicated air is standardized at 14.7 psia (103 kPa)
What does SCFM mean?
standard cubic feet per min
What does FRL mean?
Filter, Regulator, Lubricator
What is Secondary treatment?
Is the equipment outside of the supply side components
- its where we’ll find FRL
True or False: Filters need to be serviced regularly
True
How is pressure drop determined?
by measuring the difference between inlet and outlet pressure of a filter element
What happens when pressure drop reaches 10 psi?
element is starting to become clogged
How do Filters work?
purify the air - filters moisture / impurities
How do Regulators work?
designed to provide constant pressure and that pressure is not exceeded
Lets talk lube
lubing up tools (lightly) extends tools life / work
What job does a Pressure Relief Valve have?
Opens when pressure inside system reaches the PRV set point
Does the PRV fix itself?
Yes, when pressure returns to below the PRV set point, the valve re-seats / returns to service
What is a Bursting disk?
also called a rupture disk
Has an engineered weak spot
Designed to burst at a predetermined pressure
it is a one time device
What is a Fusible plug?
Located on discharge side of compressor
single use
opens when dangerous temperatures present
Who is the governing body for pressure vessel program?
Tech safe BC
When blowing dust off clothes what is the required pressure?
70 kPa gauge (10 psig)
- wear eye protection / respirator
What is the purpose of a compressed air piping system?
to deliver compressed air to wear its needed.
What must a compressed air system have?
- sufficient vol
- good quality
- enough power to power tools
When designing a layout does a projection of future demands / tie-ins to the existing distribution need to be considered?
Yes
Can compressors fail due to under sized pipes?
Yes
What is pressure drop?
reduction in air pressure from compressor discharge –> point of use
A properly sized piping system should have a pressure loss of much less than?
10% of compressors discharge pressure
Are multiple, smaller compressors w/ sequencing controls more efficient than a large compressor?
Yes
Where must the compressor be located?
In a dry, clean, cool and well - ventilated area
How is the amount of heat generated?
unit HP x 2500 BTUH
Do drains have to be vented?
Yes
What kind of line connects compressor to air distribution line?
High temp, steel braided, vibration isolated flex hose
Why should the length of piping be kept to a min?
to reduce pressure drop
What kind of valves should be used?
Always use full port valves (ball valves)
What kind of pipe is recommended?
Copper tube
Type M, L, K
Can PVC and CPVC pipe be used?
Should never be used, it can break and shatter / fling sharp fragments
What is recommended way to join pipes?
Solder or brazing
roll grooved joints –> for larger pipe
What is a velocity fuse?
a valve that closes when excessive flow begins to pass through it
- prevents air hose from whipping around if broken
What is the common fitting used to connect tools to hose?
Quick connect
