hydraulic training release 14082002

Hydraulic training 14.08.2002 3IVA/Walter page 1/ 62

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Hydraulic training16.10.2002

Filtration is the key to reliability and effective contamination control !


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Table of contents

1. Possible sources of solid-contamination of a hydraulic circuit.....................................................51.1. Added contamination ..............................................................................................................51.2. Inbuilt contamination ..............................................................................................................51.3. Generated contamination........................................................................................................6

2. Benefits of filtration.........................................................................................................................63. General requirements for filters .....................................................................................................74. Filter classification...........................................................................................................................8

4.1. Suction filter.............................................................................................................................84.1.1. The Mahle suction filter range.....................................................................................9

4.2. Pressure filter .........................................................................................................................104.2.1. The Mahle low pressure filter range .........................................................................114.2.2. The Mahle medium pressure filter range..................................................................124.2.3. The Mahle high pressure filter range ........................................................................13

4.3. Return line filter .....................................................................................................................144.3.1. The Mahle return line filter range..............................................................................15

4.4. Reservoir filters/air breathers ...............................................................................................164.4.1. The Mahle reservoir/ air breather range...................................................................17

4.5. Off-line/external loop filter/aggregate .................................................................................184.5.1. The Mahle off-line/external loop filter/aggregate range .........................................19

5. Filter designs..................................................................................................................................20


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5.1. Filter options ..........................................................................................................................205.1.1. Bypass.........................................................................................................................205.1.2. Contamination indicator (optical/electrical).............................................................215.1.3. Sampling valve...........................................................................................................235.1.4. Under-/pressure manometers ...................................................................................245.1.5. Air breather.................................................................................................................255.1.6. Coupling for filling......................................................................................................265.1.7. Automatic air bleeder ................................................................................................275.1.8. Slosh baffle / filter strainer for air breathers ............................................................285.1.9. Preload valve ..............................................................................................................295.1.10. Reverse flow valve .....................................................................................................305.1.11. Cold start valve (bypassed flow returned to tank)...................................................31

5.2. Filter connections...................................................................................................................325.3. Filter seal material..................................................................................................................335.4. Filter element material ...........................................................................................................345.5. Filter element dimensions .....................................................................................................36

6. Filter characteristics ......................................................................................................................376.1. Beta-ratio/efficiency (multipass test according ISO4572) ...................................................376.2. Filter rating (µm) ....................................................................................................................386.3. Collapse pressure (element, acc. to ISO 2941) .....................................................................406.4. Dirt holding capacity (multipass test according ISO4572)...................................................416.5. Initial differential pressure, = f(viscosity, flow rate).............................................................436.6. Fatigue strength (element and housing) ..............................................................................44


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6.7. Burst pressure (housing) .......................................................................................................456.8. Cleanliness classes for filter elements ..................................................................................46

7. Filter selection and sizing...............................................................................................................487.1. Required data for filter selection ...........................................................................................487.2. Filter sizing .............................................................................................................................49

8. Key for hydraulic filter elements and filter housings: ..................................................................518.1. Key for hydraulic elements according to Mahle standard: ..................................................518.2. Key for hydraulic elements according to DIN 24550: ...........................................................528.3. Key for hydraulic elements as replacement for competitor elements................................538.4. Key for oil separator elements ..............................................................................................548.5. Key for filter housings according to Mahle standard...........................................................558.6. Key for filter housings according to DIN 24550....................................................................568.7. Special keys............................................................................................................................57

9. Filter tests .....................................................................................................................................5810. Lab facilities..................................................................................................................................6011. Further product information – fine oil separators ......................................................................61


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1. Possible sources of solid-contamination of a hydraulic circuit

1.1. Added contamination

- contaminated air- replenishing process- worn piston rods/seals- etc.

1.2. Inbuilt contamination

- cinder- welding beads- casting sand- loose paint- fibers from rags- rust- etc.


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1.3. Generated contamination

- wear- erosion by abbrassive grit- scuff from components- particles generated by catalytic processes/oxidation- etc.

2. Benefits of filtration

- increased life expectancy of the fluid- significantly reduced risk of premature damage or

failure of components- reduced repair, replacement and maintenance costs- avoided or at least minimized down time of the production- increased reliability and therefore increased production- increased life time of critical/expensive components Scoring on a component of an axial piston pump


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3. General requirements for filters

- low cost

- easy recycleability of element

- high efficiency

- guarantee of cleanliness class

- high dirt holding capacity

- chemically resistant against fluid

- resistant against pulsation

- long service life

- easy maintenance


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4. Filter classificationThe filter is graduated according to its position in the hydraulic circuit.

4.1. Suction filter

Installed in suction line. Protection of pump. Cold start conditions must be consideredbecause of possible cavitation. Point of time for element change by regular service intervalsor contamination indicator.


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4.1.1. The Mahle suction filter range

Suction filters Dp,ini < 0,1 bar

PI 160PI 1710PI 270all simplex pressure filters


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4.2. Pressure filterInstalled in pressure line. Protection of specific components. Vibrations and pressure peaksshould be avoided.(low- / medium- /high-pressure) <63 bar / >63-210 bar / >210-450 bar

Note: Duplex filters cannot be used in the suction line.Simplex filters can also be used as suction inline filter.


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4.2.1. The Mahle low pressure filter range

Low pressure filters Dp,ini < 0,5 bar

PI 150PI 1500PI 200PI 210 (duplex)PI 220 (f-head+spin-on)PI 230 (Goldfilter)PI 270 (parallel filter)PI 2000PI 1975PI 1941PI 1931PI 1907PI 5075


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4.2.2. The Mahle medium pressure filter range

Medium pressure filters Dp,ini 0,5..0,8 bar

E 1128 (in -/outlet on one side)PI 320 (parallel filter)PI 340 (in-/outlet on one side)PI 350PI 360PI 370 (duplex)PI 3000PI 3300PI 3700 (duplex)PI 3800 (duplex SS)


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4.2.3. The Mahle high pressure filter range

High pressure filters Dp,ini <1 bar

E 1128 (in -/outlet on one side)PI 410 (f-block)PI 420PI 420 KV (cold start valve)PI 422 (L-connection)PI 430PI 440PI 450PI 480 (ss)PI 1123PI 4000PI 4000 KV (cold start valve)


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4.3. Return line filterInstalled in return line. Removal of contamination generated in the system as well asingressed through seals. Filter can be used for topping-up hydraulic tank.


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4.3.1. The Mahle return line filter range

Return line filters Dp,ini 0,2...0,5 bar

PI 500 (option: double inlet for NG 40/NG 63)PI 510 (duplex design of PI 500)PI 530


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4.4. Reservoir filters/air breathersInstalled on tank top. Air breathers can be integrated in the return line filter for air flows up to250l/min (PI 5000/1-series).

Note: The differential pressure curves are indicated for clean elements. In reality the oilvapour condenses in the element and leads to an increased differential pressure.


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4.4.1. The Mahle reservoir/ air breather range

Air breather filters, Dp,ini <0,01 bar

PI 0101-0185PI 145-149 (PI0120-0126 with increased performance)PI 0120-0126 /UMPI 0126 AD

/UM...with integrated optical contamination indicatorAD...air breather filter with air drier


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4.5. Off-line/external loop filter/aggregate

Off-line filtration should be used to supplement existing filters

Advantages of off-line filtration:

- independent from main circuit- element is not subjected to transient conditions- can be left running even when main system shuts down- elements can be changed while the main system is running- useable for charging new (old) oil into (out of) the system- as supplement to partial flow return line filters (if full flow is not

economical)- very high dirt holding capacity- increases service life for the other system filters- low cost elements because of the low operating pressure- online contamination control can (de-)activate off-line filter acc. to dirt concentration

Note: retention of off-line filter should be chosen finer than retention of the system filters.


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4.5.1. The Mahle off-line/external loop filter/aggregate range

See leaflets:

- filter aggregates ( PI 1535-158, PI 1560-158)- mobile filter aggregares PI 8100-series


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5. Filter designs

5.1. Filter options

5.1.1. Bypass

The bypass protects the element from collapsing dueto exceeding differential pressure. When the bypassvalve opens the efficiency of the filter will drop. Filterswithout bypass must have an element with increasedcollapse strength (vst-design).

Note: standard elements can be used in filters withoutbypass when the max. operating pressure does notexceed 20 bar. Filters with bypass are permissible forcleanliness classes lower than ISO 16/13 (ISO 4406)


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5.1.2. Contamination indicator (optical/electrical)

Contamination indicators are stronglyrecommended for all filters to show when theelement is clogged.

Advantage: - reduces maintenance costs- prevents failure of elements- full use of dirt holding capacity

Options: single/two step (optical/electrical), signalsuppression below 30°C, analog output,change over contact, etc.

Note: Electrical upper parts with two steps needthe corresponding mechanical indicator with two steps !

Standard electrical indicator are contact type normally closed-/normally opened and aremounted in normally closed position. By turning the electrical upper part 180°, thecontact-type can be changed to normally opened.


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Electrical under-/pressure switches are often used for suction pumps and big air breathers.(See leaflet ‚contamination indicators‘+ special leaflets, special indicator designs on request)


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5.1.3. Sampling valve

...are used to check regularly the contamination level of the fluid. Thesampling valve can be mounted instead of a contamination indicator or between filter headand contamination indicator.

A sampling valveis included in our‚Fluid samplingand adapter kit‘


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5.1.4. Under-/pressure manometers

Under-/pressure manometers are often used for return line filters and suction filters.(See leaflet ‚contamination indicators‘)


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5.1.5. Air breather

Air breathers can be integrated directly in the return line filter. PI 500-serie for up to 100l/min.PI 5000/1-series for up to 250l/min. Bigger flow rates re quire an extra air breather.

+


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5.1.6. Coupling for filling

Couplings for filling are often used for return line filters (see leaflet PI 500).


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5.1.7. Automatic air bleeder

Automatic air bleederscan be used for lowpressure filters up to 10bar operating pressure

e.g. for PI 150-series


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5.1.8. Slosh baffle / filter strainer for air breathers

Slosh baffle for PI 0126 including filter strainer.


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5.1.9. Preload valve

Preload valve, expansion kit: p/n 9735382

Preload valve opening pressures:

Inlet pressure: -50 mbar

Out let pressure: +200 mbar

Advantage: - minimized ingress of humidity- support for pump


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5.1.10. Reverse flow valve

Some applications require a possible flow in both directions. Normal filters are designed for oneflow direction only. An opposite flow would damage the element. A reverse flow valve ensuresboth possible flow directions.

Note: During reverse flow the fluid will not be filtered. The reverse flow valve can be delivered forhigh pressure filter series PI 420 with/without bypass.

normal flow (filtration) reverse flow (no filtration)


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5.1.11. Cold start valve (bypassed flow returned to tank)

Second outlet bypasses part of the inlet-flow back to the tank during excessive differentialpressure (cold start, forgotten element change). Ensures that only filtered fluid exits from themain outlet connection. Unfiltered fluid is not bypassed to the clean side but returned to the tank.

Available for the high pressure filter series:PI 420 (KV), nominal size 50, 80, 110 lPI 4000 (KV), nominal size 40,63,100 lDue to the bypass function, low pressurefilter elements can be used.

tank outlet

inlet


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5.2. Filter connections- flange (SAE, DIN, in-/outlet on one side or on opposite sides)- pipe thread (cylindrical, conical)- spin-on thread- manifold block- L-connection (90° between in- and outlet) with cylindrical pipe threads or flanges

Special connections for the US-market according to file ‚filters in US-design‘


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5.3. Filter seal material- NBR (Buna N, Perbunan, max. 120°C)- FPM (Viton, max. 180°C)- EPDM (Buna AP, max. 130°C)- PTFE (Teflon, max. 200°C)- CR (Neoprene)

Attention: max. permissible operating temperature is limited to 120°C because of the stability ofthe glued seams of the filter element (special glues on request)!


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5.4. Filter element material

- DRGwire mesh (cleanable,<60µm immersion in ultrasonic bath recommended,surface filter)

- MIC-micronicorganic (cellulose)

- Smx-super micronic, anorganic (multi-layer glas fibers)

- FIL (cellulose, extreme high dirt holding capacity but no defined retention, water absorption ispossible

- WS, standard material combined with a super absorber for water (see leaflet WS-elements)- KS, special material for coolants, efficiency like MIC 25


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Filter media Cleanable Initial Dp Minimumretention

Dirt holdingcapacity

Costs

DRG yes low >10µm low highMic no medium >5µm medium lowSmx no high >2µm high mediumFIL no high >2µm, no βx ! extreme high -WS (water removal) no medium/high >2µm high low/mediumKS (coolant lubricants) no medium Mic 25 medium low

Pleated stat design with Smx-filter material


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5.5. Filter element dimensions

(see coresponding leaflets)


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6. Filter characteristics

6.1. Beta-ratio/efficiency (multipass test according ISO4572)

xx

filterofdownstreamxparticlesofnofilterofupstreamxparticlesofno

x

ex ββ

β

1

..

−=

>>=

The micron size at βx=75 is most widely accepted as ‚absolute‘ rating.

beta e(%) beta e(%) beta e(%)


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6.2. Filter rating (µm)

beta-ratio

particle size [µm]

efficiency

%


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particle size [µm]

efficiency

%


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6.3. Collapse pressure (element, acc. to ISO 2941)

Standard elements: ∆p,max = 20 barVST-elements: ∆p,max = 210 bar


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6.4. Dirt holding capacity (multipass test according ISO4572)

Multipass test booth

This standardized test with test dust ISO-MTD determines the beta ratio and the dirt holdingcapacity of a filter element as function of the differential pressure.

3g ISO-MTD (test dust)


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6.5. Initial differential pressure, = f(viscosity, flow rate)

All ∆p-curves arealways measuredwith the various filterelements inside thecorrespondinghousing size.

Standard viscositiesindicated: 33cSt,190cSt

∆p for otherviscosities can becalculated with ourhydraulic CD-rom orwith the formulaindicated in our filterguide, page 22


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6.6. Fatigue strength (element and housing)


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6.7. Burst pressure (housing)


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6.8. Cleanliness classes for filter elements

Cleanliness classes are graduated according to :

- ISO DIS 4406 (>5µm/>15µm => class 1...24) – most commonly used !- NAS 1638 (5-15µm, 15-25µm, 25-50µm, 50-100µm, >100µm => class 00...12)- SAE 749 D- CETOP RP70H- MIL STD 1246A- NIST (see separate lecture)

Cleanliness classes graduates the dirt concentration of a fluid acc. to the number of particles withsize Xµm found within 100ml of fluid.

Necessary cleanliness classes are specified by the components manufacturers depending on theinternal clearances of components and the operating pressure.


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From our many years of experience, references for the selection of a certain filtermedia andfiltration rate can be given according to the required cleanliness class:

Cross references between NAS- and ISO-cleanliness classes can be found in our filter guide.


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7. Filter selection and sizing

7.1. Required data for filter selection

- position in the hydraulic circuit- max. operating pressurefilter rating or required cleanliness class- flow rate- viscosity (during start-up and

normal operation depending)- operating temperature- operating fluid/ material requirements- filter options/accessories

See questionnaire for fluid filters


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7.2. Filter sizing

Type of filter ∆p,max,rec[bar]

bypass VA remark

suction <0,1 √ (√) VA or maintenance period (500h), danger of pumpcavitation, VA if suction filter is only system filter,normally 100um, pump flow must be guaranteed at coldstart

low pressure <0,5 (√) √ ∆p-resistance acc. system pressuremedium pressure 0,5...0,8 (√) √ ∆p-resistance acc. system pressurehigh pressure 0,8...1 (√) √ ∆p-resistance acc. system pressurereturn line 0,2...0,5 √ √ ∆p-resistance must be >∆p bypass at cold startoff-line/externalloop

√ √ deg, of filtration normally 3um, ∆p-resistance acc. max.pump pressure

air breather <0,01 √ (√) VA recommended for flow >2000l/min, retention acc.finest system filter, maintenance interval 3000-6000hours

[√] ... without bypass only if contamination class > ISO 16/13 is acceptable √ ... always √ ... never(√) ... optional VA...contamination indicator


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Note: Choosing a larger filter capacity helps to:

- reduce running costs (less loss of energy)

- increased service life

- fewer element changes

- reduced labour costs

- reduced down time


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8. Key for hydraulic filter elements and filter housings:

8.1. Key for hydraulic elements according to Mahle standard:

PI 3 1 05 Smx 10filter material + retention nominal size

10 = Mic 25 71 = Drg vst 10 V2A 81 = Drg 10 91 = Drg vst 10 05 = 5011 = Mic 10 72 = Drg vst 25 V2A 82 = Drg 25 92 = Drg vst 25 08 = 8021 = Sm-x 3 73 = Drg vst 40 V2A 83 = Drg 40 93 = Drg vst 40 11 = 11022 = Sm-x vst 3 74 = Drg vst 60 V2A 84 = Drg 60 94 = Drg vst 60 15 = 15031 = Sm-x 10 75 = Drg vst 100 V2A 85 = Drg 100 95 = Drg vst 100 30 = 30032 = Sm-x vst 10 76 = Drg vst 200 V2A 86 = Drg 200 96 = Drg vst 200 45 = 45041 = Sm-x 25 77 = Drg vst 300 V2A 87 = Drg 300 97 = Drg vst 300 60 = 60042 = Sm-x vst 25 78 = Drg vst 500 V2A 88 = Drg 500 & cylindrical 98 = Drg vst 50051 = Sm-x 6 89 = Drg 250/400/500 99 = Drg vst. cylind.52 = Sm-x vst 6

Note: element without seal. Seal is integrated in filter head, not in element. Suitable filter housinghas 4 digit model designation. Nominal size of element and housing must correspond.Example: PI 2005-058 with element PI 3105 Smx 10.


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8.2. Key for hydraulic elements according to DIN 24550:

PI 2 3 006 R N Smx 10 NBR

filter material retention nominal size installation seal material1 = Mic 1 = 3 µm 004 = 40 D = pressure line N = NBR2 = Smx 2 = 6 µm 006 = 63 E = EPDM3 = Drg 3 = 10 µm 010 = 100 R = return line F = FPM4 = 4 = 16 µm 016 = 160 P = PTFE or5 = 5 = 25 µm 025 = 250 PTFE capsuled6 = 6 = 40 µm 040 = 400 C = CR7 = Smx vst 7 = 60 µm 063 = 6308 = Drg vst 8 = 100 µm 100 = 10009 = 9 = 250 µm0 = 0 =

S = special

Note: seal included in element. Suitable filter housing has 5 digit model designation. Nominal sizeof element and housing must correspond. Example: PI 50006-058 with element PI 23006 RN.


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8.3. Key for hydraulic elements as replacement for competitor elements

890... Hydac891... Pall892... Argo893... Internormen

Note:

We offer cross-reference databases in Excel forcompetitorsHydac, Pall,Stauff, Parkerand separateprice lists forHydac- and Pall-replacements.


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8.4. Key for oil separator elements853... wrapped elements852... pleated elements


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8.5. Key for filter housings according to Mahle standard

Housings have a 4 or 5 digit model designation followed by a 3 digit code for the options.

PI 2 0 30 - 0581= suction2= low pressure3= medium pressure4= high pressure5= return line

1=duplex7= duplex

value*10=nominal size inl/min

code for filter options012 = VAm5, Bp7013 = VAe5, Bp7014 = VAm5015 = VAe5057 = VAm2.2, Bp3.5058 = VAe2.2, Bp3.5068 = VAm2.2069 = VAe2.2

Beside of this general rule there are some exceptions as:low pressure filters PI 1941, PI 1975, PI 150high pressure filter PI 1123return line filter PI 1907, duplex filter PI 5075 etc.

Note: housing according to Mahle standard has 4 digit model designation (+ 3 digit modeldesignation for filter options). Suitable filter element has 4 digit model designation, too.Example: PI 2005-058 with element PI 3105 Smx 10.

VAm... visual contamination indicatorVAe... electrical contamination indicatorBp... Bypass valve2.2/5/7 switching level in bar


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8.6. Key for filter housings according to DIN 24550

Housings have a 5 digit model designation followed by a 3 digit code for the options.

PI 2 0 063 - 0581= suction2= low pressure3= medium pressure4= high pressure5= return line

1=duplex7= duplex

value*10=nominal size inl/min

code for filter options012 = VAm5, Bp7013 = VAe5, Bp7014 = VAm5015 = VAe5057 = VAm2.2, Bp3.5058 = VAe2.2, Bp3.5068 = VAm2.2069 = VAe2.2

Note: housing according DIN 24550 has 5 digit model designation (+ 3 digit model designation forfilter options). Suitable filter element has 5 digit model designation. Example: PI 20063-058 withelement PI 23063 DN (Smx 10 NBR).

VAm... visual contamination indicatorVAe... electrical contamination indicatorBp... Bypass valve2.2/5/7 switching level in bar


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8.7. Special keys

Beside of known standard keysthere exist some exceptionse.g. key for PI 422, PI 230 etc.(see corresponding leaflets)


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9. Filter tests

- multi-pass test according ISO 4572

- burst pressure test

- bubble point test according ISO 2942


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- initial differential pressure according ISO 3968

- collapse test according ISO 2941

- fatigue strength test according ISO 3724


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10. Lab facilities

- see filter tests- microscopic contamination analyses- particle analysis acc. ISO 4406/NAS 1638/NIST- gravimetric contamination level according DIN 51592 [mg/l]- determination of water content according to DIN 51577- IR-spectroscopy- compatibility test for combinations of material and fluids- ultrasonic cleaning of Drg-elements- leak test- determination of viscosity acc. DIN 51562- test of filterability

Prices for lab services acc. special price list.


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11. Further product information – fine oil separators

characteristics of oil separators:- max operating temperature 120°C- residue oil concentration: 1-3mg/Nm³- vertical or horizontal mounting orientation- service life: approx. 5000 hours of operation- recommended air velocity: 0.06m/s

=> wrapped elements approx. 300cm²/[Nm³/h]=> pleated elements approx. 400cm²/[Nm³/h]

Note: residue oil concentration depends on sort of oil, temperature, air velocity, preseparation,design of filter housing, quality of oil separator. Service life is only limited by solid contaminants.Therefore good filtration of air and oil is the fundamental precondition.

Our scope of supply is the fine oil separator element only !


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Appendix

hydraulic training release 14082002

Documents