1、Designation: D7721 11D7721 17Standard Practice forDetermining the Effect of Fluid Selection on HydraulicSystem or Component Efficiency1This standard is issued under the fixed designation D7721; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This practice covers all hydraulic fluids.1.2 This practice is applicable to both labora
3、tory and field evaluations.1.3 This practice gives overall provides guidelines for conducting science-based hydraulic fluid evaluations. It does notprescribe a specific efficiency test methodology.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are inc
4、luded in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior t
5、o use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers
6、 to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D4174 Practice for Cleaning, Flushing, and Purification of Petroleum Fluid Hydraulic SystemsD4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants2.2 ISO Standards:3ISO 4391 Hydraulic fluid powerPumps, motor
7、s and integral transmissionsparametertransmissionsParameter definitionsand letter symbolsISO 4392 Hydraulic fluid powerDetermination of characteristics of motorsISO 4409 Hydraulic fluid powerPositive displacement pumpsMethods of testing and presenting basic steady stateperformanceISO 5598 Fluid powe
8、r systems determined from electric power meterreadings or calculated from the mass of fuel consumed and the lower heating value of the fuel.3.2.6 fit for use, nproduct, system, or service that is suitable for its intended use.3.2.7 fuel rate, nthe rate at which fuel is consumed in L/h, normalized to
9、 the fuel density at 15 C.3.2.8 grade, ndesignation given a material by a manufacturer so that it is always reproduced to the same specificationsestablished by the manufacturer.standards organizations such as ASTM or ISO.3.2.9 hydraulic fluid, nliquid used in hydraulic systems for lubrication and tr
10、ansmission of power.3.2.10 hydraulic system, nfluid power system that is an arrangement of interconnected components which generates,transmits, controls, and converts fluid power energy.3.2.11 hydromechanical motor hydromechanical effciency, nratio of the actual torque to the derived torque.output o
11、f themotor to the theoretical torque output of the motor.3.2.8 hydromechanical pump effciency, nratio of the derived displacement to absorbed hydraulic torque.3.2.12 motor overall effciency, nratio of the mechanical output power to the power transferred from the liquid at its passagethrough the moto
12、r.3.2.13 motor volumetric effciency, nratio of the derivedtheoretical inlet flow rate to the effective outletinlet flow rate.3.2.14 outlier, nresult far enough in magnitude from other results to be considered not part of the set.3.2.14.1 DiscussionFor purposes of this practice, classification of a r
13、esult as an outlier shall be justified by statistical criteria in comparison with thevalid data points.3.2.15 pump hydromechanical effciency, nratio of the theoretical input torque of the pump to the actual torque input of thepump.3.2.16 pump overall effciency, nratio of the power transferred to the
14、 liquid, at its passage through the pump, to the mechanicalinput power.3.2.17 pump volumetric effciency, nratio of the effective output flow rate to the derivedtheoretical output flow rate.3.2.18 reference oil, noil of known performance characteristics used as a basis for comparison.3.2.18.1 Discuss
15、ionFor purposes of this practice, the reference oil may be a hydraulic fluid of any suitable composition.3.2.19 test oil, nany oil subjected to evaluation in an established procedure.3.2.19.1 DiscussionFor purposes of this practice, the test oil may be a hydraulic fluid of any suitable composition.3
16、.3 Definitions of Terms Specific to This Standard:3.3.1 design of experiment, DOE, nstatistical arrangement in which an experimental program is to be conducted and theselection of the levels (versions) of one or more factors or factor combinations to be included in the experiment.3.3.2 duty cycle, n
17、time interval devoted to starting, running, stopping, and idling when a device is used for intermittent dutyin use and the time spent operating at different levels of rated capacity.speed, displacement volume, torque, and pressure.3.3.3 effciency improvement, ndifference in system or component behav
18、ior between two fluids and this difference can apositive change in one or more parameters measured in a system or component that may be defined as an improvementa reductionin fuel consumption, work produced, electrical power draw, flow rate, temperature reduction, and so forth.or temperature, anincr
19、ease in work produced or flow rate, or any combination of these or other parameters.D7721 1723.3.3.1 DiscussionThis improvement is expressed as a percent increase that is obtained by dividing the test oil performance by the reference oilperformance and multiplying by 100 or, if appropriate, for exam
20、ple, temperature, then actual values can be reported.3.3.4 power factor, nin AC electrical circuits, the ratio of actual electric power dissipated by the circuit to the product of theroot mean square values of current and voltage. In DC electrical circuits, it is the energy consumed (watts) versus t
21、he product ofinput voltage (volts) times input current (amps).3.3.4.1 DiscussionThe power factor is the dimensionless ratio of energy used compared to the energy flowing through the wires.3.3.5 system overall effciency, nin fluid power systems, the ratio of the output power of the system to the inpu
22、t power of thesystem.3.3.5.1 DiscussionFor integral transmissions and open-loop hydraulic circuits that drive a hydraulic motor, system overall efficiency is the ratio ofthe output mechanical power at the hydraulic motor shaft to the input mechanical power at the pump shaft. Methods ISO 4391 andISO
23、4409 provide additional details for determining system efficiency in circuits with boost pumps.4. Summary of Practice4.1 The purpose of this practice is to define minimum technical requirements needed statistically to validate for conductingenergy efficiency performance comparisons of two or more hy
24、draulic fluids in controlled laboratory or field evaluations.4.2 Controls and considerations based on both technical factors and practical experience are included.4.3 Requirements for test planning, testing conduct, and data analysis and reporting are described.5. Significance and Use5.1 The purpose
25、 of a hydraulic fluid is to cool and lubricate fluid power components, as well as transmit power. Several standardtest methods are available to measure the lubrication performance of hydraulic fluids. This practice provides uniform guidelinesfor comparing fluids in terms of their power-transmitting
26、abilities as reflected in their effect on hydraulic system or componentefficiency. Standard test methods ISO 4409 and ISO 4392 provide specifications for evaluating the steady state performance ofhydraulic pumps and motors but do not address technical requirements specific to hydraulic fluid testing
27、.5.2 GeneralEnergy efficiency benefits of hydraulic fluids are the differences between two large numbers. Differences in fluidperformance may be relatively small. Consequently, it is essential to ensure that the differences observed are statistically valid(within defined confidence limits, typically
28、 95%) and that proper precautions to ensure the that the necessary experimental controlshave been put in place to compare are implemented to ensure consistency in operating conditions and duty cycle when comparingthe energy efficiency performance of two or more different hydraulic fluids under ident
29、ical operating conditions. of differenthydraulic fluid formulations.5.3 Practical advantages of enhanced hydraulic system efficiency may include increased productivity (faster machine cycletime), reduced power consumption (electricity or fuel), and reduced environmental impact (lowered emissions).5.
30、4 This practice implies no evaluation of hydraulic fluid quality other than its effect on hydraulic system efficiency.6. Procedure6.1 ProtocolAsuccessful outcome is dependent on an evaluation of goals and methods at the outset along with an assessmentof potential sources of error. Such an evaluation
31、 requires a clearly defined test protocol that shall include: (1)(1) statistical designof experiment and analysis, (2)(2) fluid order evaluation, (3)(3) equipment selection, (4)(4) analysis and mitigation of the testvariables, and (5)(5) appropriate data collection methods. This ensures that both th
32、e reference and test oils are evaluated in exactlythe same way, thus ensuring a valid comparison is made.6.1.1 Site Coordinator/Personnel TrainingBecause of the complexity of field trials, it is recommended that a designated sitecoordinator be used to ensure any questions or concerns from site perso
33、nnel are addressed and that test protocols are beingfollowed.6.2 Statistical Design of Experiment (DOE)A statistical DOE system shall be used to account for any test variability andensure any differences observed are significant to 95%95 % confidence limits.6.3 Test ControlThere are a number of test
34、 variables that can significantly influence efficiency measurements and shall becontrolled.D7721 1736.3.1 Fluid OrderTo account for the potential impact of machine drift/bias and lubricant carryover effects, it is highlyrecommended that the efficiency of the reference fluid (A) be evaluated before a
35、nd after each test fluid (B) evaluation. Alternatingthe reference fluid and test fluid in anABAorABAB test sequence is satisfactory. When operator or test equipment variables mayhave a significant impact on the test outcome, the operators and test equipment should also be alternated in a systematic
36、manner.6.3.2 Carryover ControlHydraulic systems may retain a significant amount of residual fluid after they have been drained. Thisresidual fluid can create cross-contamination. The level of cross-contamination between test fluids shall be kept to a minimum. Inpreparation for the evaluation of each
37、 fluid, the hydraulic system should be filled, flushed, and drained of the test fluid at least once.Practice D4174 provides specific recommendations to facilitate this process. The cross-contamination level in the test fluid ideallyshould not exceed 10%10 % in field trials and 1%1 % in laboratory ev
38、aluations. theThe amount of cross-contamination should bedetermined using an appropriate test method such as elemental analysis, mass balance, infrared spectroscopy, or viscosity. Thisinformation is to be included with the test results.6.3.2.1 Flushing Requirements for Surface Active Fluids (for exa
39、mple,Example, Friction Modified)If any of the fluids underevaluation containcontains surface-active friction-reducing materials (for example, friction modifiers), then extra precautions tominimize carryover effects may be required. One of these precautions shall be to use a flush oil that is capable
40、 of removing suchsurface-active additives.6.3.3 Environmental Conditions (for example, Temperature, Humidity, and Precipitation)Field Trials)It is important tominimize the effect of differences in environmental conditions such as ambient temperature during the conduct of a field test. Thismay includ
41、erequire testing only during defined periods of the day over multiple days, or on multiple days under similar weatherconditions, or collecting temperature data for subsequent analysis or correction during data analysis.conditions. Record ambienttemperature, atmospheric pressure, and sea level at the
42、 beginning of each test sequence.6.3.3.1 Precipitation shall be avoided as much as possible during testing as it is difficult to account for variation in traction.6.3.3.2 The recommended ambient temperature for machine testing is 15 C to 30 C.6.3.4 Oil TemperatureOil temperature can have a significa
43、nt influence on fluid performance and, therefore, should bemonitored to account for its influence on efficiency. Oil temperatures shall be measured as accurately as possible both in thereservoir and at the pump.pump inlet.6.3.5 Oil ViscosityOil viscosity can have a significant influence on fluid eff
44、iciency and, therefore, should be monitored fromstart to end of test to account for its influence on efficiency.6.3.6 Oil PressureOil pressure has a strong influence on hydraulic pump efficiency. It is important to ensure that theequipment is operating at comparable pressures during identical test o
45、perations between oils under test. If pressure changes as aresult of factors other than the work load (that is, leakage, pump wear) occur, the results will not be valid.6.3.7 Operator DifferencesIt is usually preferable in mobile equipment to test reference and candidate oils using the sameoperator.
46、 When not possible, procedures should be included to minimize the effects of any differences, for example, account fordifferences in DOErandomized testing and machine evaluation.6.3.8 Operating Conditions (Speed, Load, Duty Cycle)The test procedure should define as specifically as practical suchvari
47、ables as speed of operation, sequence of steps, and load.Also, the duty cycle shall be defined to hold as consistently as possiblebetween the test and reference oils. Where possible, standard duty cycles such as found in VDI 2198 should be employed.6.3.9 Fuel QualityDifferences in fuel characteristi
48、cs can contribute to changes in efficiencies during field testing. It is highlypreferable to conduct field evaluations using a single batch of fuel. When this is not possible, comparable fuel quality shall beincluded in the test protocol.6.3.10 Electronic (Controlled for Power Factor)Electric Power
49、QualityIn systems drawing power from a common sourcesuch as plant equipment, changes in load separate from the test equipment can affect electrical power quality. In systems that maybe affected, comparable power quality (for example, amps, watts, and power factor) shall be included in the test protocol.6.3.11 An accurate location to measureThe recommended location for measuring electrical power consumption is between themotor and motor starter.variable frequency drive (or starter in an across-the-line application) and the
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