applications of hydraulics&pneumatics : session 13
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13pplications of
Hydraulic Pneumatics&By: Alireza Safikhani
2 Air Compressors & Distribution System When air is compressed itWhen air is compressed it
rises dramatically inrises dramatically in
temperaturetemperature The natural water vapourThe natural water vapour
content of air (relativecontent of air (relative
humidity) is concentratedhumidity) is concentrated
and carried through theand carried through the
compression process as acompression process as a
vapour in the highvapour in the high
temperaturetemperature
As the air cools waterAs the air cools water
condenses out makingcondenses out making
freshly compressed air veryfreshly compressed air very
wetwet
Solid particles will also beSolid particles will also be
present, these can consistpresent, these can consist
of fragments of burntof fragments of burntcompressor lubricating oilcompressor lubricating oil
and airborne dust inhaledand airborne dust inhaled
by the compressorby the compressor
Preparation of compressedPreparation of compressed
air consists of reducingair consists of reducing
temperature, removingtemperature, removing
water and solids,water and solids,
controlling pressure and incontrolling pressure and in
many cases addingmany cases addinglubricantlubricant
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Condition of Air
For the continuing performance of control systemsFor the continuing performance of control systems
and working elements, it is necessary to guaranteeand working elements, it is necessary to guarantee
that the air supply is:that the air supply is:
at the required pressure,at the required pressure, drydry
cleanclean
4
Components of air Preparation
The equipment to be considered in the generation andThe equipment to be considered in the generation andpreparation of air include:preparation of air include:
Inlet filterInlet filter
Air compressorAir compressor Air reservoirAir reservoir
Air dryerAir dryer
Air filter with water separatorAir filter with water separator
Pressure regulatorPressure regulator
Air lubricator as requiredAir lubricator as required
Drainage pointsDrainage points
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6 Pressure level As a rule, pneumatic components are designed for aAs a rule, pneumatic components are designed for a
maximum operating pressure of 800 to 1000maximum operating pressure of 800 to 1000 kPakPa (8(8--
10 bar).10 bar). Practical experience has shown, however,Practical experience has shown, however,that approximatelythat approximately 600600 kPakPa (6 bar) should be used for(6 bar) should be used for
economic operationeconomic operation..
Pressure losses of between 10 and 50Pressure losses of between 10 and 50 kPakPa (0.1 and 0.5(0.1 and 0.5
bar) must be expected due to the restrictions, bends,bar) must be expected due to the restrictions, bends,
leaks and pipeleaks and pipe--runs, depending on the size of theruns, depending on the size of the
piping system and the method of layout.piping system and the method of layout.
The compressor's system should provideThe compressor's system should provide at least 650at least 650to 700to 700 kPakPa (6.5 to 7 bar) for a desired operating(6.5 to 7 bar) for a desired operating
pressure level of 600pressure level of 600 kPakPa (6 bar).(6 bar).
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Compressor Selection
the various types of compressors available andthe various types of compressors available and
selection of appropriate Compressorselection of appropriate Compressor is dependentis dependent
uponupon quantity of air, pressure, quality and cleanlinessquantity of air, pressure, quality and cleanliness
and how dry the airand how dry the air should be.should be. There are varying levels of these criteria depending onThere are varying levels of these criteria depending on
the type of compressor.the type of compressor.
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17 Reservoirs configured downstream of a compressor toconfigured downstream of a compressor to stabilisestabilise
compressed air.compressed air.
compensates the pressure fluctuations when thecompensates the pressure fluctuations when thecompressed air is taken from the system.compressed air is taken from the system.
If the pressure drops below a certain value, theIf the pressure drops below a certain value, the
compressor will compensate until the set higher valuecompressor will compensate until the set higher value
is reached again.is reached again.
the compressor does not need to operatethe compressor does not need to operate
continuously. The large surface area of the reservoircontinuously. The large surface area of the reservoir
cools the air. Thus, a portion of the moisture in the aircools the air. Thus, a portion of the moisture in the airis separated directly from the reservoir as water,is separated directly from the reservoir as water,
which has to be regularly drained via a drain cock.which has to be regularly drained via a drain cock.
18 size of a compressed air reservoir Delivery volume of the compressor
Air consumption for the applications
Network size (any additional requirements)
Type of compressor cycle regulation
Permissible pressure drop in the supply network
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Delivery volume q L = 20 m3/minDelivery volume q L = 20 m3/min
Switching cycles per hour z = 20 1/hSwitching cycles per hour z = 20 1/h
Differential pressureDifferential pressure p = 1 barp = 1 bar
Result: Reservoir size VB = 15 m3Result: Reservoir size VB = 15 m3
Volume of a reservoir20
Air dryers
The service life of pneumatic systems is considerablyThe service life of pneumatic systems is considerably
reduced if excessive moisture is carried through thereduced if excessive moisture is carried through the
air system to the components.air system to the components.
Therefore it is important to fit the necessary air dryingTherefore it is important to fit the necessary air dryingequipment to reduce the moisture content to a levelequipment to reduce the moisture content to a level
which suits the application and the components used.which suits the application and the components used.
There are three auxiliary methods of reducing theThere are three auxiliary methods of reducing the
moisture content in air:moisture content in air:
Low temperature dryingLow temperature drying
Adsorption dryingAdsorption drying
Absorption dryingAbsorption drying
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Automatic drain valve
When water level rises valveopens to eject the water
then closes again When no pressure, valve
opens to drain system
Unit fits in the bottom of afilter or drip leg drain
Nylon mesh 500 m toprevent large solid particlesclogging internals
Dead zone where largeparticles may settle
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Automatic drain valve
Float breathable forpressure equalisation,
internally splined to preventrotation
Air inlet seat
Air exhaust seat
Piston and drain valve spool
Exhaust valve wire can bepushed from below tooverride and lift the float
Connection for piping awaycontaminant
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Automatic drain valve
Pressure first applied to thebowl fully lifts the piston sothe drain is closed
The wire cracks open thefloat inlet seat until a forcebalance exists across thepiston in the closed position
Changing bowl pressure,slightly lifts or lowers thepiston to adjust thebalancing pressure
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Automatic drain valve
Water level rises but notenough to lift the float
Force holding the float down
is the pressure differentialacting on the float above theinlet seat area
Water takes on the samepressure as the compressedair in the bowl
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Automatic drain valve
Water high enough to lift thefloat
Air pressure on top of thepiston balances thepressure under it
Spring pushes piston downto open the valve
Water ejected underpressure
Exhaust seat open but air
enters faster than it canleave so the piston staysopen
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Automatic drain valve
Float drops and reseals inletseat
Water still being ejected asthe valve starts to slowlyclose
Piston pushed up slowlyagainst air pressure on topof the piston as it escapesthrough the restrictedexhaust seat
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Automatic drain valve
Piston in the up positionfully closing the valve
The cycle is repeated
whenever there is sufficientwater to lift the float
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Automatic drain valve
When system pressure isturned off and exhausted thespring will push the pistondown to open the valve
Any water gradually drainingthrough a depressurisedsystem will be able to passthrough the open drain valve
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Semi-automatic drain
When the pressure is turnedoff at the end of the day or at
any other time the drainvalve will open automatically
In most applications thenormal daily cycle will keepthe bowl cleared
If the bowl needs drainingwhile under pressure thiscan be achieved manuallyby pushing up on the pipe
connector
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Semi-automatic drain
When air pressure is OFFthe valve springs to the
open position and drainingoccurs
Water contained in the bowlwill be cleared
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Semi-automatic drain
When air pressure is ON thevalve is pushed closed
Water will start to build up in
the bowl If the level becomes too high
before the pressure isturned off it can be drainedunder pressure manually
Push up on the pipeconnector and hold untildraining is complete
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Semi-automatic drain
When air pressure is ON thevalve is pushed closed
Water will start to build up in
the bowl If the level becomes too high
before the pressure isturned off it can be drainedunder pressure manually
Push up on the pipeconnector and hold untildraining is complete
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Semi-automatic drain
When air pressure is ON thevalve is pushed closed
Water will start to build up inthe bowl
If the level becomes too highbefore the pressure isturned off it can be drainedunder pressure manually
Push up on the pipeconnector and hold untildraining is complete
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Semi-automatic drain
When air pressure is ON thevalve is pushed closed
Water will start to build up inthe bowl
If the level becomes too highbefore the pressure isturned off it can be drainedunder pressure manually
Push up on the pipeconnector and hold untildraining is complete
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Fully automatic drain valve
In normal working underpressure, the float will liftwhen the water level rises
This causes the valve toopen and the water isejected
The float falls and the valvecloses
When the pressure is turnedoff at the end of the day or atany other time the drainvalve will open automatically
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Fully automatic drain valve
In normal working underpressure, the float will liftwhen the water level rises
This causes the valve toopen and the water isejected
The float falls and the valvecloses
When the pressure is turnedoff at the end of the day or atany other time the drainvalve will open automatically
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Fully automatic drain valve
In normal working underpressure, the float will lift
when the water level rises This causes the valve to
open and the water isejected
The float falls and the valvecloses
When the pressure is turnedoff at the end of the day or atany other time the drainvalve will open automatically
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FRL
FRL stands for filter, regulator and lubricatorFRL stands for filter, regulator and lubricator
When an FRL unit is referred to, it means a combination ofWhen an FRL unit is referred to, it means a combination of
these three devices closely connected togetherthese three devices closely connected together They form a unit that will prepare the condition ofThey form a unit that will prepare the condition of
compressed air just before delivering it to pneumaticcompressed air just before delivering it to pneumatic
equipment or machineryequipment or machinery
This ensures the air supply is clean and dry, the pressure is atThis ensures the air supply is clean and dry, the pressure is at
the correct level and fine particles of oil are carried in the athe correct level and fine particles of oil are carried in the a irir
to lubricate the wearing parts within valves, cylinders andto lubricate the wearing parts within valves, cylinders and
toolstools
A convenient method of combining these components is toA convenient method of combining these components is touse a modular systemuse a modular system
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FRL
shown with gauge, shut offshown with gauge, shut off
valve and wall mountingvalve and wall mounting
bracketsbrackets
Updated system based onUpdated system based onthe popular modular yokethe popular modular yoke
with plug in unitswith plug in units
Extensive range of plug inExtensive range of plug in
unitsunits
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Olympian Plus
Quick connect yokes
Plug in unit
Bayonet bowls
Prismatic sight glass Captive O Rings
Tamper resistant cover
Pressure switch
Soft start/dump
Shut off valve 3/2
1
2
3
4
5
6
7
8
9
1
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Filter (general principle)
Separate and collectcontaminants
Angled louvers spin the airas it enters the bowl
Water droplets and largesolid particles spunoutwards against bowl andrun to the bottom
Baffle prevents turbulent airsplashing water on to thefilter element
Element traps finer solidparticles
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Filter (with manual drain)
Daily visual inspection isrequired to ensure the water
contaminant level isprevented from rising to alevel where it can be drawnthrough the filter element
A quarter turn valve allowsthe contaminant to beejected under pressure
Threaded end allows a tubeconnection for draining to a
suitable container
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Filter (with metal bowl)
Refraction grid clearlyindicates contaminant level
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Filter (with service indicator)
As a filter element becomesclogged the flow decreases
The developing pressure
differential acting on thediaphragm lifts the redsleeve
The filter element must thenbe replaced
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Filter (with service indicator)
As a filter element becomesclogged the flow decreases
The developing pressuredifferential acting on thediaphragm lifts the redsleeve
The filter element must thenbe replaced
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Coalescing filters
For applications where theFor applications where the
air is to be exceptionallyair is to be exceptionally
clean and free of oilclean and free of oil For use in food and drugFor use in food and drug
processing, air bearings andprocessing, air bearings and
paint spraying etc.paint spraying etc.
SubSub--micrometremicrometre particleparticle
removal down to 0.01removal down to 0.01 mm
Air should be preAir should be pre--filteredfiltered
down to 5down to 5 m to preventm to prevent
short element life due toshort element life due to
solid particle build upsolid particle build up
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Coalescing filter element
Air enters the inside of theAir enters the inside of the
element and passes throughelement and passes through
the filter to the outerthe filter to the outer
surfacesurface
Perforated stainless steelPerforated stainless steel
supporting formers for upsupporting formers for up
to 10 bar differentialto 10 bar differential
Filter media: borosilicateFilter media: borosilicate
glass micro fibreglass micro fibre
Foam sock diffuses air flowFoam sock diffuses air flow
to low velocity to preventto low velocity to prevent
oil reoil re--entrainmententrainment
Ends set in resin to sealEnds set in resin to seal
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Coalescing filter element
Oil aerosol particlesOil aerosol particles
coalesces (join together)coalesces (join together)
when they contact thewhen they contact the
element mediaelement media The pathways throughThe pathways through
the media are so fine andthe media are so fine and
complex that thecomplex that the
particles cannot passparticles cannot pass
through without contactthrough without contact
Oil soaks and drains toOil soaks and drains to
the bottom of the sockthe bottom of the sock
where it drips in to thewhere it drips in to thebowlbowl
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Coalescing filters
Flow ratings are lower thanFlow ratings are lower than
equivalent sized standardequivalent sized standard
units e.g. 28 dm3/sunits e.g. 28 dm3/scompared to 83 dm3/s forcompared to 83 dm3/s for
G1/2 at 6.3 barG1/2 at 6.3 bar
Filter area large for ratedFilter area large for rated
flow to keep air velocity lowflow to keep air velocity low
and prevent oil reand prevent oil re--
entrainmententrainment
Standard service lifeStandard service life
indicator monitors theindicator monitors the
pressure drop to warn whenpressure drop to warn whenelement requires replacingelement requires replacing
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Electrical service life indicator
Ideal for remote indicationIdeal for remote indication
when filter elementwhen filter element
requires replacingrequires replacing Can be used to give remoteCan be used to give remote
visual and audible warningvisual and audible warning
For sensitive applicationsFor sensitive applications
can be used tocan be used to
automatically turn off aautomatically turn off a
machine or processmachine or process
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High efficiency oil removal
High efficiency coalescingelement
Remaining oil content 0.01ppm max at + 21oC
Particle removal down to0.01 m
Air quality to ISO 8573-1Class 1.7.2(to accommodate any oilvapour carry-over that maycondense out at lowertemperatures)
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Ultra high efficiency
Active carbon pack for oilvapour and odour removal
Warning pink dye activatedif oil carries over due tocoalescing element failure
Remaining oil content 0.003ppm max at + 21oC
Particle removal down to0.01 m
Air quality to ISO 8573-1Class 1.7.1
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Coalescing silencers
For the termination of allpneumatic system exhausts
Removes lubricating oilparticles carried over in theexhaust
Large filter area keepsexhaust velocity low for verylow noise
Piped exhausts can beconnected to either end
Can be gang mounted alsowith porting blocks
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Pressure regulator
Reduces supply pressure P1Reduces supply pressure P1
to a suitable workingto a suitable working
pressure P2pressure P2 When there is no flowWhen there is no flow
demand the poppet valvedemand the poppet valve
closes to hold the pressurecloses to hold the pressure
at P2at P2
Flow demand will open theFlow demand will open the
poppet valve wide enoughpoppet valve wide enough
to satisfy the flow rate atto satisfy the flow rate at
pressure P2pressure P2
P2 can be set on a gaugeP2 can be set on a gaugefitted to the regulatorfitted to the regulator
2
4 6
8
10
40
80
120
lbf/in2
bar
P1 P2
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Pressure regulator
Reduces supply pressure P1Reduces supply pressure P1
to a suitable workingto a suitable working
pressure P2pressure P2
When there is no flowWhen there is no flow
demand the poppet valvedemand the poppet valve
closes to hold the pressurecloses to hold the pressure
at P2at P2
Flow demand will open theFlow demand will open the
poppet valve wide enoughpoppet valve wide enough
to satisfy the flow rate atto satisfy the flow rate at
pressure P2pressure P2
P2 can be set on a gaugeP2 can be set on a gauge
fitted to the regulatorfitted to the regulator
2
4 6
8
10
4080
120
lbf/in2
bar
P1 P2
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Pressure regulator
To increase pressure P2,To increase pressure P2,
pull the adjusting knob uppull the adjusting knob up
to disengage the lockingto disengage the locking
teethteeth
Turn clockwise until new P2Turn clockwise until new P2
pressure reachedpressure reached
The higher spring forceThe higher spring force
pushes the valve openpushes the valve open
The rising pressure P2 actsThe rising pressure P2 acts
under the diaphragm tounder the diaphragm to
balance the spring andbalance the spring and
allow the valve to closeallow the valve to close
2
4 6
8
10
4080
120
lbf/in2
bar
P1 P2
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Pressure regulator
When the desired pressureWhen the desired pressure
is reached the force on theis reached the force on the
diaphragm will fully balancediaphragm will fully balancethe force on the spring andthe force on the spring and
the valve will closethe valve will close
Dead end applications areDead end applications are
those that are closed ended.those that are closed ended.
The flow demand isThe flow demand is
intermittent so the systemintermittent so the system
will fill and settle at the setwill fill and settle at the set
pressure e.g (a singlepressure e.g (a single
stroke of an actuator)stroke of an actuator)
2
4 6
8
10
4080
120
lbf/in2
bar
P1 P2
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Pressure regulator
While flow is taking placeWhile flow is taking place
the valve will be held openthe valve will be held open
wide enough to keep aswide enough to keep asclose to the set pressure asclose to the set pressure as
possible for the flowpossible for the flow
demanddemand
As the flow rate increasesAs the flow rate increases
so the pressure under theso the pressure under the
diaphragm decreases todiaphragm decreases to
open the valve wider toopen the valve wider to
maintain the flow close tomaintain the flow close to
the set pressurethe set pressure
2
4 6
8
10
4080
120
lbf/in2
bar
P1 P2
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Pressure regulator
This is a relieving regulatorThis is a relieving regulator
to allow pressure to beto allow pressure to be
reduced to a lower settingreduced to a lower setting
Turn anticlockwise toTurn anticlockwise to
reduce the spring forcereduce the spring force
The higher force under theThe higher force under the
diaphragm lifts it clear ofdiaphragm lifts it clear of
the valve spindlethe valve spindle
P2 can now exhaust untilP2 can now exhaust until
the diaphragm sealsthe diaphragm seals
Turn clockwise to adjust upTurn clockwise to adjust up
to the new pressureto the new pressureP1 P2
2
4 6
8
10
4080
120
lbf/in2
bar
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Pressure regulator
Once the desired settingOnce the desired setting
has been established pushhas been established push
down the locking adjustingdown the locking adjusting
knob to prevent inadvertentknob to prevent inadvertent
changeschanges2
4 6
8
10
4080
120
lbf/in2
bar
P1 P2
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Lubricators
There are two main types ofThere are two main types of
lubricatorlubricator
One is the conventionalOne is the conventionalhigh delivery Oil Fog serieshigh delivery Oil Fog series
( coded green)( coded green)
The other is the unique andThe other is the unique and
more widely used Micro Fogmore widely used Micro Fog
range (coded red)range (coded red)
Both types are easilyBoth types are easily
adjusted to preadjusted to pre--set theset the
lubrication densitylubrication density
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Oil fog lubricators
All of the oil drips seen through the sight domeAll of the oil drips seen through the sight dome
enter the air stream and are atomisedenter the air stream and are atomised
The size range of the oil particles produced areThe size range of the oil particles produced areideally suited to lubricating single items ofideally suited to lubricating single items of
equipment on medium to short runs of pipeequipment on medium to short runs of pipe
The oil particles are carried along with the air flow,The oil particles are carried along with the air flow,
and gradually "wet out" to provide adequateand gradually "wet out" to provide adequate
lubrication for applications such as nut runners,lubrication for applications such as nut runners,
screwdrivers and other equipment requiringscrewdrivers and other equipment requiring
heavier lubricationheavier lubrication
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Oil fog lubricator
For lubricating over shortFor lubricating over short
distances where wetdistances where wet--out isout is
required earlyrequired early
Suited for; air tools, airSuited for; air tools, air
motors, single largemotors, single large
cylinders etc.cylinders etc.
Oil drips are broken up inOil drips are broken up in
the main air stream and allthe main air stream and all
particle sizes carried in theparticle sizes carried in the
airair
Drip rate is adjustableDrip rate is adjustable
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Oil fog lubricator
Oil drips visible through theOil drips visible through the
sight dome pushed by thesight dome pushed by the
pressure differencepressure difference
between Pbetween P11 and Pand P22
SyphonSyphon tube with checktube with check
valve to prevent oil drainvalve to prevent oil drain
back when there is no flowback when there is no flow
taking placetaking place
Transparent polycarbonateTransparent polycarbonate
bowl to inspect oil levelbowl to inspect oil level
Alternative metal bowl withAlternative metal bowl with
sight glasssight glass
P1
P2
P1
P2
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Micro-fog lubricator
Oil drips visible through theOil drips visible through the
sight dome pushed by thesight dome pushed by the
pressure differencepressure differencebetween Pbetween P11 and Pand P33
All drips pass through theAll drips pass through the
atomising head. Pressureatomising head. Pressure
drop Pdrop P33 created bycreated by venturiventuri
in atomising headin atomising head
Only smallest lightest 10%Only smallest lightest 10%
oil particles can make theoil particles can make the
tight turn to exit the bowltight turn to exit the bowl
carried by the pressure dropcarried by the pressure dropPP11 : P: P22
P1
P3
P1
P2
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Micro-fog lubricator
P1
P3
P1
P2
Turn the red control toTurn the red control to
adjust the oil flowadjust the oil flow
restrictionrestriction Observe the drip rateObserve the drip rate
Flexible flow sensor,Flexible flow sensor,
progressively bends flat asprogressively bends flat as
the flow increases. Thisthe flow increases. This
controls the local pressurecontrols the local pressure
drop Pdrop P11 : P: P22 to drawto draw
lubricated air from the bowllubricated air from the bowl
in proportion to flowin proportion to flow
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Micro-fog lubricator
Due to the high flow in toDue to the high flow in to
the bowl, a microthe bowl, a micro--fogfog
cannot be filled undercannot be filled under
pressurepressure
First turn off and exhaustFirst turn off and exhaust
the air supplythe air supply
Remove the bowl and fillRemove the bowl and fill
Replace bowl securelyReplace bowl securely
Turn on the airTurn on the air
To fill under pressure,To fill under pressure,
replace filler plug with areplace filler plug with a
nipple adaptornipple adaptor
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FRL
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Relief valve
Spring force preventsnormal air pressure from
lifting the diaphragm Excessive pressure will lift
the diaphragm to open thepoppet valve and relieve airto the outlet
When the pressure drops tothe pre-set value again thespring closes the diaphragmpoppet OutIn
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Relief valve
Spring force preventsnormal air pressure from
lifting the diaphragm Excessive pressure will lift
the diaphragm to open thepoppet valve and relieve airto the outlet
When the pressure drops tothe pre-set value again thespring closes the diaphragmpoppet OutIn