Oil Soluble Polyalkylene Glycol Hydraulic Fluid: Equipment Performance Testing and Case Study Authors Andrew Larson, The Dow Chemical Company Dr. Martin Greaves, The Dow Chemical Company The Dow Chemical Company STLE Annual Meeting 2014 Orlando Synthetic and Hydraulic Lubricants I May 19 th, 2014
Contents Introduction Performance Testing Case Study Fire Resistance Testing Conclusions
Introduction
Background and History of PAGs in Hydraulic Fluids First use of PAGs was in water glycol fire resistant fluids (HF-C) dating back to the 1950s In 1990s, PAGs were adopted as synthetic anhydrous fire resistant hydraulic fluids (HFDU) Since 2000, PAGs have been used as HEPG hydraulic fluids in environmentally sensitive areas Offer high biodegradability Non-sheening and water soluble Used in equipment where risk of spills into the environment are concerning
Further Innovation in PAGs Oil Soluble PAGs Traditional building blocks used in designing PAGs New building block used in the design of OSPs Homo-polymers or Copolymers (random and block) are often used for lubricants Oil soluble PAGs are new and build on 60 years of experience in using PAGs across many lubrication industries
Traditional PAGs vs. Oil Soluble PAGs Oil miscibility Viscosity index Pour points New OSPs Traditional PAGs Traditional PAGs used in water based lubes and as primary base oils in synthetics Elastomer compatibility Biodegradability OSPs retain many of the benefits of traditional PAGs with some additional benefits Deposit control Oxidation stability Hygroscopicity Hydrolytic stability Antiwear OSPs can open up the application envelope by using them as performance enhancing additives in hydrocarbon oils which has never been possible before
Examples of Physical Properties of OSP Base Oils for HEPG or HFDU Hydraulic fluids Test Method OSP-A OSP-B OSP-C Kinematic viscosity at 40 o C, mm 2 /sec ASTM D7042 32 46 68 Kinematic viscosity at 100 o C, mm 2 /sec ASTM D7042 6.5 8.5 12 Viscosity Index ASTM D2270 146 164 171 Pour Point, o C ASTM D97-57 -53-53 Brookfield viscosity at -26 o C, mpa. s ASTM D2983 3130 5570 12500 Air release, minutes ASTM D3427 <1 <1 <1 Aniline point, o C ASTM D611-01 <-30 <-30 <-30 Biodegradability, % OECD 301F 75 34 22 Heat capacity at 60 o C, J/g/ o K Dow Internal 2.12 2.07 2.07 FKM Volume change, 1000 hours ISO-6072 1.2 1.0 0.9 NBR Volume change, 1000 hours ISO-6072 16 2-0.4
Industry Trends for Hydraulics Higher system pressures Higher operating temperatures Compact systems with smaller reservoir sizes Tighter clearances Finer filter pores Performance Needs Important Lubricant Feature Pump reliability Low compressibility Operating temperature range Deposit and varnish free Water tolerance Air tolerance Particulate contamination Wear protection High bulk modulus Viscosity index and low temperature properties Oxidation stability and cleanliness Water separation and corrosion protection Air release and foam control Filterability
Performance Testing
Performance Properties of OSP Hydraulic Fluid OSP Hydraulic Fluid Component % OSP (ISO 46) 98.2 Additive Package 1.8 Additive package contains classical anti-oxidants, antiwear and corrosion inhibitors No requirement for VI improvers, pour point depressants or detergents Typical Performance Properties Test Method Result Kinematic Viscosity at 40 ºC, cst ASTM D445 45.9 Kinematic Viscosity at 100 ºC, cst ASTM D445 8.2 Kinematic Viscosity at 0 ºC, cst ASTM D7042 463 Viscosity Index ASTM D2272 157 Pour Point, ºC ASTM D97-54 Density at 15 ºC, g/ml ASTM D7042 0.968 Ferrous Corrosion, 24 hours, deionized water/synthetic sea water ASTM D665A/B Pass/Pass Copper Corrosion ASTM D130 1a Foam Sequence I, II and III, ml ASTM D892 0/0 Four Ball Anti-wear, mm ASTM D4172 0.31 Air Release at 50 ºC, minutes ASTM D3427 <1 Oxidation at 121 ºC, 70 days KV40 change, % Visual Appearance after 70 days Thermo-oxidative Stability Test at 95 ºC, TAN change after 1000 hours, mg KOH/g (wet conditions) ASTM D2893B ext. time 1.3 Trans. no deposits ASTM D943 +0.5
Air Release A measure of the time required for free air bubbles to be released to the surface Air often enters through suction line Poor air release in hydraulic equipment can result in Erosion and cavitation Noise Spongy controls Air release values generally increase with increasing ISO viscosity grades V = 2 (ρ f ρ a ). r 2.g 9 ŋ V = rate of ascent of air bubbles Ρ f = density of fluid P a = density of air r = radius of bubble Ŋ = viscosity of fluid Research has shown very fast air release of OSP fluids May have practical advantages in the design of smaller reservoirs especially for mobile equipment
Hydraulic Fluids Air Release Properties Air release, min Commercially available ISO 46 fluids Test method: ASTM D3427 at 50 ºC 15 10 5 0 Primary Base Oil in Commercially Available Formulation Air release, min Mineral oil 4 PAO Ester 5 Vegetable oil 8 Water glycol 13 Polyol oleate 7 3 Traditional PAG 7 Phosphate ester 1 OSP <1
Eaton 35VQ25A Vane Pump Testing Formulated synthetic OSP hydraulic fluid (ISOVG-46) Pump Conditions: 2400rpm, 3000psi, 93oC, 3 x 50 hours Weight Loss of Test Cartridges Eaton 35VQ25 vane pump, weight loss of cartridge 1, 2 and 3, mg ASTM D6973-05 16/23/15 Before test After test Kinematic viscosity at 40oC, mm2/sec 46.8 47.3 Kinematic viscosity at 100oC, mm2/sec 8.4 8.4 Water content, % 0.07 0.05 Acid Number, mg KOH/g 0.19 0.24 Iron (Fe), ppm Copper (Cu), ppm Tin (Sn), ppm Lead (Pb), ppm Boron (B), ppm Silicon (Si), ppm Zinc (Zn), ppm Phosphorus (P), ppm <1 <1 <1 <1 <1 2 137 <1 <1 <1 <1 2 6 117 Fluid Analysis Property A cam ring on 3rd cartridge Outlet side plate 3rd cartridge
Additional Performance Testing Formulated synthetic OSP hydraulic fluid (ISOVG-46) FZG Gear Wear Test (ASTM D4998) Test conditions = 121 ºC, 20 hrs, 100 rpm Weight loss = 7.3 mg FZG Load Stage Test (ASTM D5182) Failure load stage = 10 Elastomer Compatibility (ISO 1817 Modified) Elastomer batch: SRE-NBR-1 Test temperature = 100 ºC Test duration = 168 hrs Avg. volume change = 7.91% Avg. points hardness change = -5
Case Study
Trial of OSP-based Hydraulic Fluid Application Background Equipment for moveable swimming pool floors and submersible booms Creates swimming venues that have a great deal of flexibility and provide high board diving, swimming, aqua-aerobics, toddler paddling etc Previously had some challenges with their hydraulic system (corrosion) including hydraulic fluid degradation (chemical and oxidative). One conversion complete to OSP-based hydraulic fluid with seven more in process
Product Selection Product corrosion testing was critical (modified ASTM D665) OSP-based hydraulic fluid showed good ferrous corrosion testing in chlorinated swimming pool water at contamination levels up to 10%
Trials on OSP-based Hydraulic Fluid Trials conducted using a Marzocchi GHP-2 External Gear Pump - Displacement = 4.5-35 cm 3/rev - Speed = 2500-4000rpm - Max. continuous pressure = 160-280 bar Trial Conditions - Tank containing two 17/4PH Cr-plated piston rods - Hallite seals - 6 week trial - 500 strokes/ day and 2500 strokes/ week - Pool temp. = 30oC - Chlorine levels 3-4ppm
Performance Data 49 KV40, cst 48 47 Cylinder 1 End A 46 Cylinder 2 End A 45 Cylinder 1 End B 44 Cylinder 2 End B 43 0.2 42 3 weeks 6 weeks 0.16 Water, % Start Cylinder 2 End A 0.08 Cylinder 1 End B Cylinder 2 End B 0.04 0.79 TAN, mgkoh/g Cylinder 1 End A 0.12 0 0.78 0.77 Cylinder 1 End A 0.76 Cylinder 2 End A 0.75 Cylinder 1 End B Cylinder 2 End B 0.74 0.73 Start 3 weeks 6 weeks Start 3 weeks 6 weeks
Performance Data Cylinder 1 End A Appearance KV40, cst KV100, cst TAN, mgkoh/g Water, % Carbonyl content, ppm P, ppm S., ppm Fe, ppm Cu, ppm Cr, ppm Cl, ppm Na, ppm Start 0 week clear 44.3 8.2 0.78 0.07 0 146 8.7 <5 2.2 Cylinder 1 End B 3 weeks clear 46.5 8.5 0.76 0.15 0 144 3.5 <5 2.2 End 6 weeks clear 47.3 8.5 0.76 0.06 0 143 2.8 <5 2.2 Cylinder 2 End A Appearance KV40, cst KV100, cst TAN, mgkoh/g Water, % Carbonyl content, ppm P, ppm S., ppm Fe, ppm Cu, ppm Cr, ppr Cl, ppm Na, ppm Start 0 week clear 46.4 8.4 0.77 0.02 0 145 26 <5 2.2 Appearance KV40, cst KV100, cst TAN, mgkoh/g Water, % Carbonyl content, ppm P, ppm S., ppm Fe, ppm Cu, ppm Cr, ppm Cl, ppm Na, ppm Start 0 week clear 45.4 8.4 0.77 0.11 0 146 6 <5 2.1 3 weeks clear 45.7 8.3 0.76 0.18 0 144 3.6 <5 2.1 End 6 weeks clear 47.0 8.5 0.76 0.08 0 145 2.8 <5 2.1 Cylinder 2 End B 3 weeks clear 46.2 8.4 0.76 0.10 0 143 2.7 <5 2.2 End 6 weeks clear 47.6 8.5 0.75 0.13 0 143 3.7 2.5 <5 2.2 Appearance KV40, cst KV100, cst TAN, mgkoh/g Water, % Carbonyl content, ppm P, ppm S., ppm Fe, ppm Cu, ppm Cr, ppr Cl, ppm Na, ppm Start 0 week clear 44.0 8.3 0.77 0.13 0 146 20 <5 2.2 3 weeks clear 46.9 8.6 0.76 0.05 0 144 2.7 <5 2.2 End 6 weeks clear 47.8 8.5 0.76 0.07 0 143 3.1 <5 2.2
Key Learnings from Trial Fluid is chemically and shear stable Fluid meets all desired elastomer testing requirements Fulfills corrosion testing requirements Fluid shows good wear performance Additional conversions are in process based on first trial s success
Fire Resistance Testing
Classification of Fire Resistant Fluids Classification Description HFAE HFC-E (a) Oil-in-water emulsions containing >95% water (v/v) and up to 5% of additives Chemical solutions in water containing >75% water (v/v) and an additive package and water soluble polymer thickener Water-in-oil emulsions that typically contain >40% water (v/v) and an additive package Water polymer solutions containing >35% water (v/v), a high molecular weight polyalkylene glycol thickener and an additive package HFC fluids with a lower water content of about 20% water (v/v) HFDR Anhydrous synthetic phosphate esters containing an additive package HFDU Anhydrous synthetics (other than phosphate esters). For example polyol esters, vegetable oils and polyalkylene glycols. The base oil represents about 95% of the formulation with an additive package. HFAS HFB HFC (a) Not an official ISO category
Fire Resistance Assessment often made based on a range of tests Spray Flammability Hot Manifold Ignition Hot Channel Wick Flame Soaked Cube test Fire point and flash point are also relevant Examined performance with two tests Stabilized Flame Heat Release method Hot Manifold Ignition test
Fire Testing Results Fully formulated (i.e. contain a base oil and performance additive package) Based on an ISO-VG-46 classification RI Value RI Factor Manifold ignition test ISO-15029-2 ISO-15029-2 (ISO14935) Polyol Oleate Ester 5 Class H 373-425 Water Soluble PAG 11 Class H 342-373 Water Insoluble PAG 12 Class H 342-373 OSP 10 Class H 342-373 Base Oil (a) 7th Luxembourg Report 3.1.3.6. The ignitability factor (RI) is graded into ranges with the least flammable having a RI >100
Conclusions OSP-based hydraulic fluid offers exceptional air release, oxidation stability and wear properties Unique air release properties may open up opportunities for designing mobile equipment with smaller reservoirs. Some OSPs offer biodegradability and could be used in designing future environmentally friendly HEPG type fluids Case study showed that OSP-based hydraulic fluid could be successfully used in field OSPs did not show any significant difference from PAGs in terms of fire resistance based on Stabilized Flame Heat Release method and Hot Manifold test OSPs have better hydrocarbon oil compatibility than conventional PAGs and may be a better practical choice in converting equipment from a hydrocarbon oil to an OSP-based fire resistant hydraulic fluid
Acknowledgements We acknowledge David Phillips who consulted on the examination of the OSP-hydraulic fluid in field testing.
Thank You