1、Designation: D7721 11Standard 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 revisio
2、n, 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. Scope1.1 This practice covers all hydraulic fluids.1.2 This practice is applicable to both laboratory and fielde
3、valuations.1.3 This practice gives overall guidelines for conductingscience-based evaluations. It does not prescribe a specificefficiency test methodology.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard doe
4、s not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Stan
5、dards:2D4174 Practice for Cleaning, Flushing, and Purification ofPetroleum Fluid Hydraulic SystemsD4175 Terminology Relating to Petroleum, PetroleumProducts, and Lubricants2.2 ISO Standards:3ISO 4391 Hydraulic fluid powerPumps, motors and inte-gral transmissionsparameter definitions and letter sym-b
6、olsISO 5598 Fluid power systems efficiency; field testing; hydraulicfluid; shear stabilityAPPENDIXES(Nonmandatory Information)X1. PRACTICAL UNITSX1.1 Field evaluations of the effects of fluid selection onsystem efficiency generally yield results in terms of work perunit time or work per unit energy.
7、 Laboratory evaluations of theeffect of fluid selection on system or component efficiencygenerally yield results in terms of volumetric, hydromechanicalor overall efficiency. The results of laboratory evaluations maybe presented in either tabular or graphical form using thepractical units shown in T
8、able X1.1 and the equations providedin Appendix X2 (tables and equations referenced fromISO 4391).D7721 114X2. CALCULATIONSX2.1 Eq X2.1-X2.8 enable the presentation of results inpractical units (see Table X1.1).X2.1.1 Mechanical Power, kW:Pm 52pn!T60 000(X2.1)X2.1.2 Hydraulic Power, kW:Ph 5qVp!600(X
9、2.2)X2.1.3 Pump Volumetric EffciencyRatio of the effectiveoutput flow rate to the theoretical output flow rate:hVP5qVqVi5qVVin!(X2.3)X2.1.4 Pump Hydromechanical EffciencyRatio of thetheoretical torque to the actual torque:hhmP5TiT5p!Vi2pT(X2.4)X2.1.5 Pump Overall EffciencyRatio of the power trans-fe
10、rred to the liquid, at its passage through the pump, to themechanical input power:hOP5PhPm5hhmPhVP(X2.5)X2.1.6 Motor Volumetric EffciencyRatio of the actualrotational speed to the theoretical rotational speed:hVM5nni5nViqV! (X2.6)X2.1.7 Motor Hydromechanical EffciencyRatio of theactual torque to the
11、 derived torque:hhmM5TTi52pTd p!Vi(X2.7)X2.1.8 Motor Overall EffciencyRatio of the mechanicaloutput power to the power transferred from the liquid at itspassage through the motor:hOM5PmPh5hVMhhmM(X2.8)ASTM International takes no position respecting the validity of any patent rights asserted in conne
12、ction with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsi
13、ble technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful co
14、nsideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100
15、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM we
16、bsite(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).TABLE X1.1 Practical UnitsQuantity Symbol Unit DescriptionPump or motor displacement Vi l Volume of fluid displaced by a pump or a motor per shaft revolutionARotationa
17、l frequency n min-1Number of revolutions of the shaft per unit timeTheoretical rotational frequency nimin-1Theoretical shaft speed is determined from the relationship ni5qvViVolume flow rate qVL/min Volume of fluid crossing the transverse plane of a flow path per unittimeTheoretical volume flow rate
18、 qViL/min Theoretical flow is determined from the relationship qVi= nViTorque TNmMeasured value of the torque in the shaft of the test componentTheoretical torque Ti Nm Theoretical torque is determined from the relationshipTi 5 pVi/2pPressure p Bar Fluid pressure, relative to atmospheric pressureDif
19、ferential pressure dp Bar Fluid pressure difference, motor inlet versus motor outletHydraulic power Ph kWMechanical power Pm kWVolumetric efficiency hV.Hydromechanical efficiency hHM.Overall efficiency hO.AReport the basis for Vi. Derived displacement (in accordance with ISO 8426) or geometric displacement in accordance with manufacturers specification may be used.D7721 115
