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The Impact of Lubricating Oil Formulations on

Filter Element Charging Behavior

J. K. Duchowski, Ph.D., HYDAC FluidCareCenter GmbH, Sulzbach, Saar, Germany

T. Lang, Ph.D., HYDAC FluidCareCenter GmbH, Sulzbach, Saar, Germany

E. Koch, Dipl.-Ing. (FH), HYDAC FluidCareCenter GmbH, Sulzbach, Saar, Germany

P. Bhavbhuti, M. Eng., HYDAC Technology Corporation, Bethlehem, PA, USA

B. Omlor, MBA, HYDAC Filtertechnik GmbH, Marketing, Sulzbach, Saar, Germany

May 20-24, 2018

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Variety of Oil Types

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Predict and Understand How Oils Behave

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Oil Used for FlushingLeads to ESD Problems

• Zinc-free

• Very low conductivity!

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Oil thought to be originally employed

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IR Results

0

10

20

30

40

50

60

70

80

90

100

5007501000125015001750200022502500275030003250350037504000

Tran

smis

sio

n [

%]

Wellenlänge [cm-1]

IR Spektrum Hitachi

Hydraulic oil Multi

Hitachi 5000

1750 – 1735 cm-1

Hydraulic

Oil GREEN

Alky Phenol

Hydraulic Oil

RED

2,6-Di-Tertiär

-Butyl-4-cresol

Tritolyl phosphate

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Examples of Oil Additive Chemistries

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Examples of Oil Additive Chemistries

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Electrostatic Test RigPhysics of ESD in Liquids

Presence of Ions Required to Carry Charge

• Typical Hydrocarbon Conductivities up to ~100 pS•m-1

Possible Charge Carriers

• Metal-containing Additives (ZnDTP, Ca/Mg sulfonates)

• Decomposition due to Oxidative or Chemical Attack

• Various Impurities (metal chips, water)

• Charge Formation Due to Helmholtz Double Layer

S

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Electrostatic Test RigOil Conductivity

S

Group VI

Saturated

hydrocarbon

(%)

Sulfur –

content

(%)

Description

Electrical

Conductivity

@RT

I 95-105 < 90 > 0,03 Conventional High

II 105-120 ≥ 90 ≤ 0,03 Hydrogenation Low

III > 120 ≥ 90 ≤ 0,03Strong

HydrogenationLow

IV > 130 100 0,00PolyAlphaOlefines

(PAO)Low

V - - - All other base oils Different

Classification of lube and hydraulic fluids acc. to

API1509, APPENDIX E, E.1.3, REV:01-SEP-2011

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Electrical Conductivity and Permittivity of Water

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Oil Used for FlushingLeads to ESD Problems

• Zinc-free

• Very low conductivity!

© 2018 HYDAC International GmbH. All rights reserved, also reference the disposition, utilization, reproduction, editing, passing on and also application for property rights.13

Predict and Understand How Oils Behave

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Predict and Understand How Oils Behave Oil 1 Oil 1

Oil 2 Oil 2

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Field Test, Jan. 2016Set I and Set II of Stat-X® Elements

Element Set II:

(optimized)

delivered Jan. 2016

Element Set I:

shipped Dec. 2015

Heavy arcing!

Charging reduced,

not eliminated;

arcing still apparent;

however…POLARITY REVERSED !

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Field Test, May 2016Set III of Stat-X® Elements

Element Set III

(further optimized)

shows great behavior

under flushing and

normal flow

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COMPOSITION/INFORMATION ON INGREDIENTS

Hazardous components Oil 1

OEM C - Field Test for Forklift

*Fluid Temperature. Start-ups at ambient temperatures below this are possible provided that the bulk fluid is allowed to warm up prior to

being put under working load.

Properties Test Method Oil 1 Oil 2

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OEM C - Field Test for Forklift

Filter:HYDAC RFM 165 with plastic pipe

Element:HYDAC 0165 R 010 BN4HC

Flow: 60 L/min

Oil Temperature: 25 °COil Conductivity: 12 pS/m

HYDAC 0165 R 010 BN4HC @ 60 L/min

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OEM C - Lab Test for Forklift

Filter:HYDAC RFM 165 with plastic pipe

Element:HYDAC 0165 R 020 BN4HC SFREE-3

Flow: 27 L/min

Oil Temperature: 25 °COil Conductivity: 12 pS/m

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Summary and Conclusion

• ESD Evaluations Require Sophisticated Equipment

• Current Models Provide Reasonably Good

Interpretation of ESD Phenomena

• High Degree of Predictability of ESD Occurrence

Achieved

• Ability to Solve Even Complex Cases within Reach

• Nevertheless: ESD issue NOT Completely Solved

• New Oil and Additive Formulations, New System

Component Materials and Unusual Operating

Conditions Create Environments Requiring Further

Investigation