1、AIR1362REV.BIssued 1975-05Reaffirmed 2008-07Revised 2000-08Superseding AIR1362AAerospace Hydraulic Fluids Physical Properties1. SCOPE:This SAE Aerospace Information Report (AIR) presents data on hydraulic fluids which are of interest to detail designers of hydraulic systems and components for aerosp
2、ace flight vehicles. The data pertain to fluids conforming to specifications MIL-H-5606, MIL-H-8446, MIL-PRF-27601, MIL-PRF-83282, MIL-H-53119, MIL-PRF-87257, Aerospace Standard 1241 Type IV, Classes 1 and 2, and Type V. The relative merits of hydraulic fluid properties in relation to the fluid form
3、ulation, aerospace hydraulic system design and the related materials compatibility are discussed in AIR81, Hydraulic Fluid Properties. This document is essentially a metric document with English units available in the data charts for convenience. There is a treatment of conversions between ISO and E
4、nglish units in AIR1657.2. APPLICABLE DOCUMENTS:The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the
5、event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.2.1 SAE Publications:Available from SAE, 400 Common
6、wealth Drive, Warrendale, PA 15096-0001.AIR81A Hydrocarbon-Based Hydraulic Fluid PropertiesAIR1657A Handbook of Hydraulic Metric CalculationsAS1241C Fire Resistant Phosphate Ester Hydraulic Fluid for Aircraftg36g40g53g50g54g51g36g38g40g3g44g49g41g50g53g48g36g55g44g50g49g3g53g40g51g50g53g55SAE Techni
7、cal Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the
8、 sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2008 SAE International All rights reserved. No part of this publication may be reprod
9、uced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-77
10、6-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 2 -2.2 U.S. Government Publications:Available from DODS
11、SP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.MIL-H-5606 Military Specification Hydraulic Fluid, Petroleum Base; Aircraft, Missile and Ordnance, NATO Code Number H-515 (Inactive for New Design)MIL-H-8446 Military Specification Hydraulic Fluid, Nonpetrol
12、eum Base; Aircraft (Canceled)MIL-PRF-27601 Performance Specification Hydraulic Fluid, Fire Resistant, Hydrogenated Polyalphaolefin Base, High Temperature, Flight Vehicle, MetricMIL-PRF-83282 Performance Specification Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base, Metric, NATO Code Numb
13、er H-537MIL-H-53119 Performance Specification Hydraulic Fluid, Nonflammable, Chlorotrifluoroethylene Base (Inactive for New Design)MIL-PRF-87257 Military Specification Hydraulic Fluid, Fire Resistant; Low Temperature, Synthetic Hydrocarbon Base, Aircraft and Missile, NATO Code Number H-5383. DESCRIP
14、TION OF PROPERTIES:3.1 Hydraulic fluids have many physical and chemical properties which must be considered in the design of a hydraulic system as follows:TABLE 1Property Effect1. Bulk Modulus System stiffness2. Viscosity Power losses3. Density System weight4. Specific Heat Thermal characteristics5.
15、 Thermal Conductivity Heat exchanger design6. Thermal Expansion Reservoir design7. Fire Resistance Safety and survivability8. Chemical Stability Formation of breakdown products9. Thermal Stability Deterioration of fluid properties10. Shear Stability Loss of lubricity and viscosity11. Hydrolytic Stab
16、ility Corrosion12. Lubricity Component wear13. Compatibility System materials14. Volatility Cavitation and evaporation15. Toxicity Safety16. Foaming Cavitation and system stiffnessCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted
17、without license from IHS-,-,-SAE AIR1362 Revision B- 3 -3.1 (Continued):NOTE: The above listing sequence has no bearing on relative importance. Properties 1 through 7 have specific numerical values which are required in detail design and analysis work; data covering these properties are given in the
18、 document. Properties 8 through 16 are important considerations in the selection of a hydraulic fluid for a specific application, but numerical values associated with these properties are not usually required in system design.The types of hydraulic fluid considered to be most applicable to air vehic
19、les are:NOTE: AS1241, Type IV phosphate ester fluid is used in two different versions, Class 1, a low density (specific gravity 0.990 to 1.020), and Class 2, a high density (specific gravity 1.020 to 1.066). Type V phosphate ester is a higher temperature fluid, with specific gravity 0.97 to 1.02. Wh
20、ere available, data for both classes and types are provided.TABLE 2Fluid Type Operating Temperature SpecificationPetroleum base withpolymeric additives-54 to 135 C MIL-H-5606Silicate ester -54 to 204 C MIL-H-8446(Canceled)Synthetic hydrocarbonfire resistant-40 to 288 C MIL-PRF-27601Synthetic hydroca
21、rbon,fire resistant-40 to 205 C MIL-PRF-83282Nonflammable, chloro-trifluoroethylene base-54 to 135 C MIL-H-53119Synthetic hydrocarbon,fire resistant-54 to 135 C MIL-PRF-87257Phosphate ester, fireresistant-54 to 107 C AS1241, Type IV,Classes 1 and 2-54 to 135 C AS1241, Type VCopyright SAE Internation
22、al Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 4 -3.2 Operating conditions can cause changes in the physical properties of a hydraulic fluid. Temperature andn pressure, in particular, have significan
23、t influences on fluid viscosity and bulk modulus. The detail designer requires data for specific operating conditions, but these data are often not readily available. This results in designers acquiring, through various means, a personal file of hydraulic fluid properties. The intent of this documen
24、t is to encourage the use of standardized design information. Fluid specifications provide for variations in properties which can result from diferences in manufacturing processes or base stocks used. The data presented herein are considered to be nominal values.4. HYDRAULIC FLUID PROPERTIES:4.1 Bul
25、k Modulus:Bulk modulus is a term used to denote the ability of a fluid to resist volumetric reduction caused by applied pressure and is an important parameter in the design of hydraulic servo systems. Interaction of fluid compressibility with the mass of the mechanical parts and load produces a natu
26、ral frequency in hydraulic systems. This resonance is often the chief limitation to dynamic performance and is approximately proportional to the square root of the fluid bulk modulus. Pressure is generally measured as gauge pressure while all equations in this document use absolute pressure.4.1.1 Th
27、ere are several different types of bulk moduli; selection of the proper modulus is based on the function being performed. Functions that occur rapidly, with little chance for heat transfer into or out of the system, require adiabatic moduli; examples include hydraulic pumps, motors, and rapidly osci
28、llating servo actuators. Functions that occur slowly or with constant fluid temperature require isothermal moduli; this modulus has limited application to air vehicle hydraulic systems. Pressure excursion magnitude is also a factor in modulus selection. Large excursions, for example in pumps and mot
29、ors, require the use of secant moduli; small pressure fluctuations around a quiescent level, as in oscillating servo actuators, require the use of tangent moduli. Bulk modulus is the reciprocal of fluid compressibility and is generally expressed in Pascal (Pa). The most commonly used moduli are summ
30、arized below:Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 5 -4.1.2 Bulk modulus is defined by:(Eq. 1)and,(Eq. 2)where:t= Adiabatic tangent bulk modulus, Pas= Adiabatic sect
31、ant bulk modulus, PaP = Pressure, PaV = Volume at pressure P, m3Po= Reference pressure, usually atmospheric, PaVo= Volume at pressure Po, m3TABLE 3FunctionPressureExcursionBulkModulus ApplicationDynamic Small1AdiabatictangentDesign of servo systemsand actuatorsDynamic Large2AdiabatictangentDesign of
32、 hydraulicpumpsStatic Small IsothermaltangentLimited use in airvehicle system designStatic Large IsothermalsecantLimited use in airvehicle systems design1Less than 10% of system pressure (approximately).2More than 80% of system pressure (approximately).tVPV-=sVoPoPVoV-=Copyright SAE International Pr
33、ovided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 6 -4.1.2 (Continued):Equation 1 is the thermodynamic definition of bulk modulus and represents the true rate of volumetric change at the pressure of “interes
34、t“. Equation 2 defines a “mean“ bulk modulus and represents the volumetric change with pressure from atmospheric to the pressure of “interest“.Both moduli can be determined under isothermal or adiabatic conditions.Two methods used for measuring bulk modulus are the pressure-volume-temperature method
35、, which gives isothermal secant information and the sonic method which yields adiabatic tangent data. Relationships between the moduli are:(Eq. 3)where:at= Adiabatic tangent bulk modulus, Pait= Isothermal tangent bulk modulus, Pais= Isothermal secant bulk modulus, Pacp= Specific heat at constant pre
36、ssure, J/(kg K)cv= Specific heat at constant volume, J/(kg K) = Fluid mass density, kg/m3c = Velocity of sound in the fluid, m/sBulk modulus can be substantially lowered by the presence of entrained air (free bubbles) in the fluid. Dissolved air has a minor effect in reducing bulk modulus. The amoun
37、t of air which can be dissolved in hydraulic fluids is approximately proportional to the pressure level. The time required to achieve equilibrium conditions may prevent complete dissolution in some cases. Generally, when the operating pressure exceeds the saturation pressure, bulk modulus degradatio
38、n due to air is small.atit- =itat pressure P is approximately equal to isat pressure 2Patc2=cpcv-=Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 7 -4.1.3 The bulk modulus dat
39、a presented in this document cover temperatures from +38 to +149 C at pressure from 0 to 55 mega Pascal (MPa).4.2 Viscosity:Viscosity causes a fluid to resist flow, varies with ambient condition and contributes to characterizing flow as laminar or turbulent. Fluid viscosity nearly always limits the
40、lowest operating temperature of a hydraulic system and often limits the highest operating temperature. Fluid systems and components have conflicting viscosity requirements, i.e., good lubrication and low internal leakage require a moderately high viscosity while low line losses and fast control resp
41、onse dictate a low viscosity fluid. Good design requires a thorough consideration of the effects of operating conditions on viscosity and the efect of viscosity variations on system performance.TABLE 4Figure No. Bulk Modulus Hydraulic Fluid1 adiabatic tangent MIL-H-56062 MIL-H-84463 MIL-PRF-276014 M
42、IL-PRF-832825 MIL-H-531196 MIL-PRF-872577 AS1241, Type IV, Class 18 adiabatic secant MIL-H-56069 MIL-H-844610 MIL-PRF-2760111 MIL-PRF-8328212 MIL-PRF-8725713 isothermal secant MIL-H-560614 MIL-H-844615 MIL-PRF-2760116 MIL-PRF-8328217 MIL-H-5311918 MIL-PRF-8725719 AS1241, Type IV, Class 1Copyright SA
43、E International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 8 -4.2.1 Fluid flow causes shear stresses within the fluid which vary with the velocity gradient across a given sheared section. For Newton
44、ian fluids the shear stress is proportional to the velocity gradient across a given sheared section. For the non-Newtonian fluids the shear stress is not proportional to the velocity gradient.The shear equation for Newtonian fluids is as follows:(Eq. 4)where: = Shear stress, Pa = Absolute viscosity,
45、 Pa s= Velocity gradient across sheared section of thickness ds, s-1Many models have been proposed for the shear equation for non-Newtonian fluids. In general some of these equations can be written as:(Eq. 5)where:n depends on the model chosenL= Limiting-shear-strength of fluid, Pa4.2.2 The ratio of
46、 absolute viscosity to fluid mass density occurs frequently in flow analyses. This ratio is, by definition, the kinematic viscosity of the fluid.(Eq. 6)where: = Kinematic viscosity, mm2/s or centi-Stoke (cSt) = Absolute viscosity, mPa.s or cP (centi-Poise) = Mass density, g/cm3Kinematic viscosity at
47、 atmospheric pressure is easily measured with commercially available viscometers. Kinematic viscosity has units of cm2/s called Stokes. Because this unit is large, the term centistoke (cSt) is often used.duds-=duds-us-1L-n1/n=-=Copyright SAE International Provided by IHS under license with SAENot fo
48、r ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1362 Revision B- 9 -4.2.2 (Continued):The viscosity of hydraulic fluids decreases significantly as temperature is increased. This relationship can be plotted using ASTM viscosity graph paper resulting in a straight line plot or approximated by:(Eq. 7)where:T= Absolute viscosity at Temperature T, Pa so= Viscosity at reference temperature To, Pa s = A temperature-viscosity coefficient which depends upon the fluid, 1/CT = Temper
