2 9 Theissen Paper - Custo Biodegradáveis

8/18/2019 2 9 Theissen Paper - Custo Biodegradáveis

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Bio-based Oils in Hydraulics – Experiences from Five Yearsof Market Introduction in Germany

Heinrich Theissen

Institute for Fluid Power Drives and Controls (IFAS), RWTH Aachen University, Germany

Klaus Jakob

Klaus-Martin Jakob

JAKOB FLUID TECHNOLOGIE AG /Jak1/, Auf der Kinzig 44, 79112 Freiburg-Tiengen, Germany

ABSTRACT

In Germany, the government sponsored Market Introduction Program has been helping to

accelerate the establishment of bio-based lubricants, and especially of bio-based hydraulicfluids, in the German mobile hydraulics market. The technical and marketing-related

experiences from five years scientific and technical assistance are summarized. Successful

converting practice for existing equipment, as performed by a specialized company, is

explained in detail.

1 INTRODUCTION

In the year 2000, the German Market Introduction Program "Bio-based Fuels andLubricants" /MEP1/ was installed with an annual funding of approx. 10 million Euros.

The purpose of the program was to give new momentum to the then stagnant bio-

lubricants market. It is being sponsored by the German Ministry of Agriculture and

administered by the Fachagentur Nachwachsende Rohstoffe e. V. (FNR) /FNR1/.

Meanwhile, more than 13,000 hydraulic systems have been changed over, and the

market share of bio-based hydraulic oils in mobile applications has doubled from 3%

to 6%. IFAS has been in charge of scientific and technical assistance to this program.

2 DEFINITION OF BIO-LUBRICANTS

The main demand for bio-lubricants comes from mobile hydraulic applications.

Construction, forestry and agricultural equipment have large quantities of hydraulic

fluid on board, high pressures, and many exposed pipelines, flexible hoses, and

connections, resulting in hydraulic oil being considered a high loss risk fluid.

Many companies and their customers involved in the use of these machines try to

minimize damage caused by fluid loss, using environmentally friendly fluids. These

fluids are in short called bio-oils.


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Yet the term "bio-oil" has not been standardized at all, and it is being used widely for

all kinds of substances, ranging in the extremes from zinc-free mineral oil to salad

oils from organic production; to explain the various uses of bio-oil related terms in

technical applications, some definitions are given in table 1.

(readily)

biodegradable oil

an oil that passes a biodegradability test, e. g. OECD 301 /OEC1/; the

former CEC test is no longer recognized as valid

bio-oil any lubricant that is easily biodegradable and less toxic than mineral oil

bio-based oil subset of bio-oils containing a major amount (in general 50% or more)

of renewable raw materials (RRM)

RRM (renewable

raw material)

material that has been produced during the last 100 years in plants or

animals

ester a class of substances whose molecules consist of alcohols and organic

acids; esters can be natural (plant and animal fats) or synthetic

synthetic ester a synthetic ester can be made from natural or petrochemical raw

materials, or a mixture of both

HETG ISO 15380 classification of environmentally friendly hydraulic fluids

consisting mainly of unmodified natural fats (plant oils) /ISO1/

HEES ISO 15380 classification of environmentally friendly hydraulic fluids

consisting mainly of synthetic esters /ISO1/

Table 1: Definitions of bio-oil related terms

In the German Market Introduction Program, only bio-based oils with at least 50%

RRM are being accepted as eligible for subsidies. They can be found in a so called

Positivliste in the internet /MEP1/. The new European Ecolabel "Euromarguerite",

figure 1, also requires hydraulic fluids to be of at least 50% RRM /The1, RAL1/.

Figure 1: Euromarguerite symbol


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3 COST OF OPERATION

Bio-based oils are more expensive (3 .. 5 €/liter) than common mineral hydraulic oils

(1 .. 1,50 €/liter). But the purchase price is only one of many cost factors. When oils

can be used for a longer period of time before being replaced, their purchasing priceis no longer an important part of the hourly operating cost of a machine. Oil life – both

mineral oil and bio-oil – can be extended considerably through good maintenance.

While this has not been an issue in the times of cheap mineral oil, where oil used to

be replaced frequently, there are better ways to run a machine, saving oil,

mechanical wear, and down time. More details will be given below.

Figure 2: Cost comparison fluid related cost, bio-oil and mineral oil

A cost comparison for a Unimog utility vehicle with a 100 liters system volume

including attachments is given in figure 2 . The graphs show the sum of oil

replacement cost including leakage losses, labor, lab tests, and filter. While it is clear

that a more expensive hydraulic fluid leads to a higher hourly cost at first, this

difference tends to disappear as the oil change intervals are expanded. Lower

accident clean-up cost, higher machine availability, longer machine life, and improved

public relations with bio-oils are important savings, but difficult to quantify, and have


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not been included into this calculation. So the real hourly cost at longer intervals may

be even lower than shown in the figure 2 , and the bio-oil cost may well be under the

mineral oil cost.

4 TECHNICAL EXPERIENCES

Bio-oils are mature products and perform well in thousands of applications. There are

presently 180 hydraulic oils, including UTTO and STOU, on the Positivliste /MEP1/.

When problems do occur with bio-oil, the main cause is contamination with mineral

oil, either as a consequence of an improperly performed change over (contamination

with old mineral fluid), or from errors during operation and maintenance

(contamination with new mineral fluid).

The industry standard for a change over from mineral oil to bio-oil is a 2% maximum

contamination with mineral oil /VDM1, ISO1/. Any major contamination may lead to

excessive formation of zinc soap and other unwanted by-products, causing foaming,

filter clogging, and premature degradation of the fluid.

The 2% level is difficult to achieve, as most mobile hydraulic equipment have smaller

reservoirs containing little more than half of the total system fluid. In order to remove

the other half of the fluid, partial disassembly and flushing are required. The number

of flushing cycles depends on the degree of oil removal that can be achieved bydraining. Estimates are given in a change over work instruction (in German language)

which is available in the internet /The2/.

Even after successful flushing and change over, mineral oil can continue to cause

problems. Organizational precautions are necessary to avoid accidental refilling with

mineral oil, especially when different oils are still available on the work site, when

machines are given to other users, or when attachments are switched between

machines.

Contamination with water and solid particles are factors that limit fluid life and cause

mechanical wear. It is recommended to use bypass micro-filtering to reduce the

contamination level. Several companies indicate that oil change intervals can be

extended up to six-fold with micro-filtering, but no systematic research results could

be found on this issue. Longer oil usage has to be supported by repeated oil tests at

500 hour intervals approximately. Oil tests also give an early indication of increased

wear, allowing to plan preventive maintenance, and reducing unplanned

interruptions.


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Water can be a problem in equipment with pressurized reservoirs. When reservoirs

are closed with a check valve instead of an open air filter in order to improve pump

inlet pressure, evaporation of humidity is blocked, and water accumulates in the

system. It can then only be removed effectively with special water removing filter

cartridges, with added labor and material cost compared to an open system.

Laboratory experiments by Kempermann /Kem1/, and recent field experiments with

forestry equipment by Tobisch /Tob1/, have demonstrated that water in the fluid

evaporates within a few hours of normal operation, if natural air exchange driven by

normal fluctuations of reservoir fluid level is allowed and not blocked. An excavator

and a forwarder, both in forestry service in southern Germany with serious water

problems, after receiving normal air filters instead of the factory-mounted check

valves, were able to evaporate most of their humidity content and reached an

acceptable 400 ppm level within less than a couple of days of normal operation. The

graph in figure 3 shows the water content in the forwarder during a later experiment

with an open air filter. Water has been added twice during this experiment and

allowed to evaporate through reservoir level fluctuation during normal operation. It

takes less than 100 hours to return to a normal level – the evaporation rate was 10

ppm per hour.

Figure 3: Reduction of humidity through natural evaporation /Tob1/


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Limited compatibility with plastic materials (seals, flexible hoses) can be a problem,

especially when older equipment has to be converted to bio-oil. However, most

newer equipment (after 1995 approx.) in good condition does not require any special

measures.

5 CUSTOMER SATISFACTION WITH BIO-BASED OIL

A 2004 user survey has shown that an impressive 88% of users were either satisfied

or very satisfied with their conversion. 10% were moderately satisfied, and only 2%

were unhappy and planning to go back to mineral oil. This is a very positive result,

especially considering the popular prejudices against bio-based oils. The survey is

being repeated in 2005, but results were not yet available at press time.

Of those moderately satisfied users, there was a relatively high number of either not

knowing the percentage of mineral oil contamination achieved during flushing, or of

not having installed bypass filtering, or both. This underlines the importance of good

flushing and good maintenance for smooth operation and customer satisfaction.

6 EXAMPLES OF SUCCESSFUL CHANGE OVER PRACTICE

In the following, a typical conversion from mineral oil to bio-oil will be described, as

performed by JAKOB FLUID TECHNOLOGIE AG /Jak1/. The company has been

founded in 2001, after having gained experience with hydraulic equipment and

especially with bio-oils during several years. In the mean time, certifications

according to ISO 9001 and ISO 14001 have been achieved. To-date, 900 machines

have been converted to bio-based lubricants and hydraulic oils.

6.1 Preparations

Switching over from mineral oil to bio-based hydraulic oil requires special care, since

both types of fluid must not be mixed. Before exchanging fluids, a sample of the oldoil is taken from the warm hydraulic system, and the contamination level is measured

with a laser particle counter, shown in figure 4. The water content in the fluid can

also be determined with a portable test equipment at the machine.

Hydraulic cylinders are then retracted as far as possible, making sure that most of the

fluid will be in the reservoir. Then the system will be depressurized and locked

against accidental movements, the ignition key is taken off, the main interrupter is

switched off. When everything is off, the hydraulic fluid reservoir is depressurized.


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Figure 4: Portable particle counter with classification feature

6.2 Flushing

After removing the fluid with a vacuum cleaner, the reservoir is wiped out. At the

same time, cylinders and pipelines are drained, and all hydraulic filters are replaced.

After that, new oil is pumped into the reservoir through a 3-micrometer fine filter. The

reservoir will be overfilled as much as possible. Then all hydraulic pumps are vented.

If the atmospheric pressure is not sufficient for venting the pumps, the reservoir must

be pressurized with 0.3 bar (30 kPa).

After careful venting the system is started up on for a short moment, then vented

again once or twice. Care has to be taken that foam does not enter the pumps, as

shown in figure 5 . The measuring connections are tapped to check if all pumps are

delivering oil. It is essential to move all functions completely during the flushing

operation. Every cylinder is being slowly moved and retracted 15 times. Rotating

motors are being moved in both directions for 2 minutes each way several times, as

shown in figure 6 . This is the only way to guarantee a complete exchange of fluids.

After having flushed for 20 to 30 minutes the machine is switched off again and

locked and depressurized.


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Figure 5: Removing foam from the reservoir

Figure 6: Flushing the traction motors


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6.3 Repeated Flushing

The whole flushing cycle as described above is repeated, including drainage of

reservoir and system, refilling and venting. Normally, two flushing cycles are

necessary. With unfavorable reservoir/system ratios, a third cycle may be necessary. After completing each flushing cycle, the residual mineral oil content is measured

with the portable equipment.

After the final fill, all functions are moved again, and all attachment pipes for gripper,

hammer, etc. are flushed. All separate attachments are flushed with a special

hydraulic power unit.

6.4 Final Steps

A last sample is taken, and particle count and residual mineral oil content are

measured. During the change over, any visible defects encountered in the machine

have been photographed and reported to the customer. Some observations made

during the preparation phase are shown in figures 7 , 8 , and 9.

Figure 7: Excessive dirt on filter


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Figure 8: Cleaning rag found on return filter

Figure 9: Brass basket missing on pump inlet filter


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The equipment is marked with several stickers indicating the type of oil that has been

filled. Especially the reservoir opening has to be marked to avoid refilling with the

wrong fluid. Every equipment receives a bio-passport with all technical data and the

date of conversion.

The customer has to be informed about all conversions performed on his site, who

has converted which machine, when it has been converted, and whatever attention

points are necessary. There has to be enough stock of the right oil for refilling needs.

Hydraulic filters will have to be replaced again after 50 hours of operation to remove

any dirt deposits that have been mobilized by the bio-oil. The next oil sample should

be scheduled after 500 hours.

6.5 Experience with Family-owned Machines

In order to gain sufficient experience, all machines on the owner family's farm have

been converted to bio-based motor oil, hydraulic oil, transmission and wet-brake oil,

and grease. These machines include the following types: tractors MB-trac 1500

turbo, MB-trac 1000, Unimog 1500 turbo, Case 1455 XLA turbo, combines MF 520

und MF 187 and various trailers and hydraulic attachments.

All hydraulic functions have been working successfully in an outside temperature

range between minus 15 °C and plus 40 °C and have not shown any defects.Besides the hydraulic circuits, also the engines were converted. The six-cylinder

engines, mostly turbos, have been running since 2001 with a 5W40 bio motor oil. The

engines have a very good low temperature start-up behavior. Oil pressure builds up

immediately, even at low temperatures, so that wear during the start-up phase is kept

low. The older engines with between 8,000 and 10,000 operating hours were

reduced considerably in oil consumption. Even under heavy conditions, refilling was

seldomly necessary. Fuel consumption can be lowered too, because of the good

properties of the low friction oil.

All machines are being greased with a bio-based synthetic ester grease. Even the

heavily stressed bearings of the combines and the corn straw shredder are being

serviced with this grease. So far, no damage or excessive wear has been observed

at the bearings.


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REFERENCES

/FNR1/ www.fnr.de

/ISO1/ International Standard ISO 15 380 "Schmierstoffe, Industrieöle und

verwandte Produkte (Klasse L) - Familie H (Hydraulische Systeme) - Anforderungen für die Kategorien HETG, HEPG, HEES und HEPR"

/Jak1/ JAKOB FLUID TECHNOLOGIE AG, Auf der Kinzig 44, 79112 Freiburg-

Tiengen, Germany, phone (07664) 5279, [email protected]

/Kem1/ Kempermann, Chr., Ausgewählte Maßnahmen zur Verbesserung der

Einsatzbedingungen umweltschonender Druckübertragungsmedien, Diss.

RWTH Aachen 1999

/MEP1/ www.bioschmierstoffe.info /OEC1/ OECD 301, OECD Guideline for Testing of Chemicals

/RAL1/ Competent Body for Ecolabel in Germany: RAL Deutsches Institut für

Gütesicherung und Kennzeichnung, Sankt Augustin, www.ral.de

/The1/ Theodori, D., European Eco-label Lubricants, Greentech Conference

Proceedings, Potsdam 2005

/The2/ Theissen, H., Arbeitsanweisung "Umstellen auf Bioöl" , Aachen 2005,

available in www.bioschmierstoffe.info

/Tob1/ Tobisch, R., Langzeiterprobung neuer biogener, biologisch schnell

abbaubarer Hochleistungs-Hydraulikflüssigkeiten mit ökotoxologisch un-

bedenklichen Additiven in der Forstwirtschaft , Abschlussbericht, KWF,

Gross-Umstadt 2005

/VDM1/ Einheitsblatt VDMA 24 568 Biologisch schnell abbaubare Druck-

flüssigkeiten – Technische Mindestanforderungen; VDMA 24 569 Richt-

linie für die Umstellung von Druckflüssigkeiten auf Mineralölbasis nach

DIN 51 524 auf biologisch schnell abbaubare Druckflüssigkeiten und

erforderliche Maßnahmen für den Betrieb
http://www.fnr.de/http://www.fnr.de/mailto:[email protected]://www.bioschmierstoffe.info/http://www.ral.de/http://www.ral.de/http://www.bioschmierstoffe.info/http://www.bioschmierstoffe.info/http://www.bioschmierstoffe.info/http://www.ral.de/http://www.bioschmierstoffe.info/mailto:[email protected]://www.fnr.de/

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2 9 Theissen Paper - Custo Biodegradáveis