portable air after sales market department basic compressor knowledge
TRANSCRIPT
Portable Air After Sales Market Department
Basic compressor knowledge
Portable Air After Sales Market Department
Effective Absolute pressure
atmosphericpressure
absolutepressure
effectivepressure
total pressure
pressure = 0
Portable Air After Sales Market Department
Absolute pressure8 bar (118 psi)
Atmospheric pressure 1 bar (15 psi)
Effective pressure7 bar (103 psi)
Effective pressure
• The effective pressure is the difference between absolute pressure and atmospheric pressure
• It is the pressure available to deliver work
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Effective pressure
• XRVS 455 Md : receiver pressure during unload is 27 bar (397 psi)
• Forces on the air receiver cover (0.08 m²) is more then 22,000 kgf (about 48k pounds)
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Free Air Delivery
• Free Air Delivery :is the measured “real” delivered volume of air (in l/s or m³/min or cfm) at the same conditions of pressure and temperature at the air inlet
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Free Air Delivery
• FAD is not equal to the displacement volume of the compressor element, because internal losses in the element (leaks to air inlet)
• FAD is independent from the ambient conditions (temperature & pressure)
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Screw Compressor
• Introduced in 1958 by Atlas Copco
• Male and female rotors move towards each other, while the volume between them and the housing decreases.
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Screw Compressor
• Screw profile improved in 1966
• Symmetrical screw was changed to an asymmetrical helical profile
• 10% more efficiency
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Compression principle
Com
pres
sion
sta
rt
Com
pres
sion
Suc
tion
Del
iver
y
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Pressure Ratio
• Each screw element has a fixed, integrated pressure ratio
• This depends on :– length of the rotors– Pitch of the screw– form of the discharge port
• Best efficiency is reached when the pressure ratio is adapted to the required working pressure
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Screw Compressor Design Advantages
• High shaft speeds and large flow rate :– gives small exterior dimensions
• Simple and strong design :– no valves and seals reliable and maintenance
friendly– small dirt particles improve the sealing and the
efficiency– almost pulsation free air
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Screw Compressor Design Advantages
• Low wear :– guaranteed long life time and constant capacity– life time is determined by the bearing wear
• Absolute oil free design possible
• No inertia forces– vibration free operation– high speeds possible– big power possible
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Screw Compressor Design Disadvantages
• Lower efficiency because of internal leaks• High quality bearings on the rotors required
– rotor clearances are small – axial bearings needed
• Noise level (high frequency)• High quality finishing of the rotors required
– expansion of rotors through heat results in blocked elements
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Oil injected screw compressors
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Oil injected screw compressors
• Oil is used for :– Cooling : compression heat is absorbed by the oil– Lubrication of rotors, bearings, gears– Sealing between rotors and rotor and housing– Corrosion protection of the internal metal parts
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Oil injected screw compressors
Oil is injected in the bottom of the rotor housing, onto thebearings and gears, and discharged with the compressed air
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Oil injected screw compressors
• Only one rotor is driven, this rotor then drives the other one :– old XAS 90 : female driven rotor– all other compressors : male driven rotor
• When required a gear box or drive belt brings the compressor element to the correct speed
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Compressor running condition
• Four major running conditions :– NO-LOAD
Machine started, minimal pressure build-up– LOAD
Receiver tank pressurized and air consumption– UNLOAD
Receiver tank pressurized, no air consumption– BLOW-DOWN
Machine stopped, blow-off of air pressure
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• Air filter Compressor Element (AFCE) (with
vacuator valve VV, Safety Cartridge SC and vacuum indicator VI)
• Unloading Valve (UV)
• Compressor Element (CE)
• Temperature Switch (TS)
• Check Valve (CV)
• Air Receiver (AR)
• Non Return Valve• Minimum Pressure Valve (MPV)
• Air Outlet Valve (AOV)
Air system
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Air filter
• Filtration of the inlet air in 3 stages :– centrifugal dust separation– paper filter element– safety cartridge (optional)
• Vacuum indicator gives an indication when the pressure drop over the filter element is too high filter element needs to be replaced
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Air filter
Air inlet Centrifugal separation
Dust
Filter element
to compressor element
Vacuum indicator
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Unloading valve
• Opens and closes the air inlet to the compressor element.– Open position at load condition
=> Air consumption– Closed position at no load condition
=> No air consumption.
• Control of the valve by regulating pressure.
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Unloading valve
Valve
Spring loaded
Regulating pressure Air inlet
Integrated blow-down valve
Vent Hole
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Unloading valveLOAD UNLOAD
Reg
ulat
ing
pres
sure
Air inlet
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Check valve
• Check valve is integrated in the unloader for Series 6 compressors (XAS 185, 375, 400)
• Closes when the compressor is stopped.
• The air receiver is pressurized, which would result in a reverse air flow. the check valve prevents this.
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Check valveLOAD BLOW-DOWN
Receiver pressure return after shut-down
Check valve
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Air receiver / Separator
Air/Oil
Centrifugal separation
Separator element
Air outlet
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Minimum pressure valve / nozzle
• Guarantees a minimum pressure in the oil separator (approx. 45-60 psi)
• Minimum pressure is required to guarantee an continuous oil supply to the element.
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Nozzle / Minimum pressure valveMINIMUM PRESSURE VALVE
NOZZLE
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Oil system
• Air receiver
• Oil cooler
• Oil filter
• Oil stop valve (where used)
• Compressor element
• Oil separator
• Scavenge line
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Oil system (without TBV)
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Oil System (with TBV)
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Air receiver
Oil flow
Pressure
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Oil coolerCool Oil
Warm Oil
Cooling air
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Oil filter
Dirty Oil Filtered Oil
By-pass valve
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Compressor element
Oil
Oil
Air/Oil
Greasing to the bearings
Air inlet
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Oil separator
Air/Oil
Centrifugal separation
Separator element
Oil
Scavenge line
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Regulating system
• Regulating valve
• Unloading valve
• Speed regulator
• Blow-down valve
• Safety valve
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Regulating system (XAS 185)Regulating Valve
Unloading Valve
Speed Regulator
Safety Valve
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Regulating valve
• Regulates the effective pressure in the air receiver
• Provides regulating pressure to :– unloading valve
=> regulates the air inlet according the air requirements
– speed regulator=> regulates the engine speed to reduce fuel consumption
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Regulating valve
Spring loaded
Adjusting receiver pressureby changing spring tension
Pressure gauge
to speed regulatorto unloading valve
Regulating pressure
Receiver pressure
to blow-down valve
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Regulating valveLOAD UNLOAD
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Speed regulator
• Regulates the engine speed in relation to the required air flow
• Load condition : maximum engine speed
• Unload condition : minimum engine speed
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Speed regulator
Spring loaded
Regulating pressure Vent Hole
Engine speed
- Min
- Max
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Speed regulatorLOAD UNLOAD
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Blow-down valve
• Blows off the air receiver pressure once the compressor has shut-down=> this to depressurize the receiver tank
• Integrated in the unloading valve
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Blow-down valve
blow
-dow
n va
lve
Receiver pressure
blow-off hole
Air inlet
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Blow-down valveLOAD / UNLOAD BLOW-DOWN
Receiver pressure
Receiver pressure return after shut-down
Blow-off receiver pressure
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Safety valve
• Blows off the air receiver pressure once this pressure raises above the design pressure.
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Electrical system
• Battery voltage : 12 or 24 V
• Starting system– cuts-out starter motor when engine is running– avoids cranking when receiver tank is pressurized
• Safety shut-downs
• Instrument indications
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Safety shut-downs
• Compressor :– Compressor element outlet temperature
• Engine :– Coolant temperature– Coolant level– Oil pressure– Fuel level
• Emergency stop
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Air treatment options
• Aftercooler
• Water separator
• Fine filters PD / QD
• Re-heater
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Air treatment options
Portable Air After Sales Market Department
Aftercooler - Water separator
• The aftercooler is a heat exchanger, which cools the hot compressed air to precipitate the water that otherwise would condensate in the air hose.
• The outlet temperature is ambient + 7°C.• It is followed by a water separator that separate
the condensate and drains it• Used for : sandblasting, fibre optic cable steering,
pipe cleaning
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Aftercooler - Water separator
Water separator
Aftercooler
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Fine filters PD / QD
• PD filter will separate oil and solid particles.
• QD filter or carbon filter will separate oil and water vapour.
• Discharge air is instrument quality--nearly “oil free”.
• Only 0.003 ppm oil present in the air outlet
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Fine filters PD / QD
PD filter
QD filter
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Re-heater
• The re-heater is a heat exchanger, which warms up the compressor outlet air to ambient + 60°C.
• The water and oil will be vaporized resulting in hot and dry air, this avoids condensate problems.
• XAS 46-96 : engine oil warms up the compressed air.
• XAS 146-186 : compressor oil warms up the compressed air
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Product nominationoil injected compressors
X A M S 750 C d
Product rangeX : Oil injected portable compressor
Working principleA : Single stage compressorR : Two stage compressor
Working pressure Single stage Two stage
: standard pressure 7 bar/100psi 17 bar/250psiM : medium pressure 8.6 bar/125psi -T : “ten” pressure 10.3 bar/150psi -H : high pressure 12 bar/175psi 20 bar/295psiV : very high pressure 14 bar/200psi 25 bar/365psi
Silencing : Un-silencedS : Silenced
Capacity (FAD)Liter/secCFM (US-version)
Engine supplierC : CaterpillarD : DeutzG : Detroit DieselJ : John DeereK : KubotaY : Yanmar
Prime moverd : diesel engineE : electric motor
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Contact Numbers•Main Number Atlas Copco Technical Support 800-732-6762 Option 3
•Ed Kukfisz – Compressors – Supervisor 281-542-2562 direct & 832-385-4697 mobile
•Andrew Stevenson – Compressors: Low Pressure720-479-2486 direct & 404-751-6717 mobile
•Andrew Calendar – Compressors: High Pressure720-479-2487 direct & 404-242-6203 mobile
•Scott Ellinger – Compressors720-479-2476 direct & 720-375-1795 mobile
•Robert Walsh – Generators – Supervisor 803-487-0256 direct (mobile)
•Will Hudson – Generators/Compressors 800-732-6762 Ext. 12920 & 832-454-8123 mobile
•Brandon Hobbs – Hydraulic Attachments /Handheld Construction Tools – Supervisor 303-287-8822 direct & 913-424-4039 mobile
•Al Eckenfels – Hydraulic Attachments/Handheld Construction Tools800-760-4049
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Committed tosustainable productivity.