1、 _ SAE Technical 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 ther
2、efrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this
3、publication may be reproduced, 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: +1 724-776-49
4、70 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J968/2_201509 SURFACE VEHICLE RECOMMENDED PRACTICE J968-2 SEP2015 Issued 1966-08
5、 Revised 1991-05 Reaffirmed 2015-09 Superseding J968-2 DEC2002 Diesel Injection Pump TestingPart 2: Orifice Plate Flow Measurement RATIONALE J968-2 has been reaffirmed to comply with the SAE five-year review policy. 1. ScopeThis part of SAE J968 specifies the flow measuring system, including the fix
6、ture, to be used for flowtesting the single hole orifice plates used in an orifice plate type nozzle and holder assembly (described inSAE J968-1) which is intended for testing and setting diesel fuel injection pumps on test benches.The flow measuring system and fixture ensure accurate flow testing o
7、f the entire range of orifices from 0.4 to0.8 mm diameter as specified in SAE J968-1. It is intended primarily for use by the manufacturers of singlehole orifice plates.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein.
8、 The latest issue of SAE publications shall apply.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J967Calibration Fluid for Diesel Injection Equipment SAE J968-1Diesel Injection Pump TestingPart1: Calibrating Nozzle and Holder Assemblies2.1.2 ISO PUBLI
9、CATIONAvailable from ANSI, 25 West 43rd Street, New York, NY 10036-8002.ISO 7440/2Road vehiclesFuel injection equipment testingPart 2: Orifice plate flow measurement3. Orifice Plate Flow Measuring System3.1 General DescriptionAn orifice plate flow measuring system shall comprise:a. Orifice Plate Hol
10、ding Fixture (shown in Figure 1)b. Fluid Supply Circuit and Flow Measuring Device (an example is shown in Figure 2)c. Flow Overcheck DeviceOPTIONAL. (This device is for periodic overchecking of the accuracy of theprimary flow measurement device in (b) and is specified in Appendix A.1.)FIGURE 1ORIFIC
11、E PLATE HOLDING FIXTURE FOR FLOW MEASUREMENTFIGURE 2FLUID SUPPLY CIRCUIT WITH PRESSURE AND TEMPERATURE CONTROLAND FLOW-MEASURING DEVICE_ SAE INTERNATIONAL J968-2 SEP2015 2 of 6The system shall be designed and constructed to minimize fluid evaporation, contamination, aeration, andinstability of press
12、ure and temperature.Flow values obtained by alternative systems shall require correlation with values determined using theprevious system.3.2 Orifice Plate Holding FixtureThe functionally critical details and dimensions of the fixture are shown inFigure 1. Dimensions not specified and construction t
13、echniques are left to the discretion of the manufacturer ofthe fixture, but shall be such that the fixture has unrestricted and undistributed flow.4. Flow Measuring Procedure4.1 General Requirementsa. The orifice plates shall be clamped in a fixture conforming to Figure 1.b. The following monitoring
14、 points shall be provided and the values measured or verified:1. Orifice inlet temperature2. Orifice inlet pressure3. Orifice outlet pressurec. The fluid shall enter the orifice through the entry cone.d. The flow through each orifice plate shall be measured individually.e. The fluid in the flow circ
15、uit shall conform to SAE J967. Viscosity and specific gravity shall bemeasured frequently and the fluid shall be discarded if it ceases to conform to SAE J967.4.2 Reference ConditionsThe orifice plate flow values stated in Part 1 of this document refer to volumetric flowrate measured (or adjusted to
16、) 40 C. The other reference conditions shall be as follows:a. Inlet pressure minus outlet pressure = 100 barb. Outlet pressure = ambient pressurec. Inlet temperature of fluid = 40 Cd. Dynamic viscosity at 40 C = 2.1 x 103 Ns/m2e. Density at 40 C = 0.808 g/cm 3NOTEDynamic viscosity at 40 C = kinemati
17、c viscosity at 40 C x density at 40 C.4.3 Accuracy of Measurement4.3.1 Measurements shall be taken with the following accuracies:a. Orifice volumetric flow rate at 40 C: 0.2% of readingb. Temperature of volume measured: 0.5 Cc. Dynamic viscosity at 40 C: 0.1 x 103 Ns/m 2d. Density at 40 C and at atm
18、ospheric pressure: 0.001 g/cm3NOTEDensity is preferably measured at ambient temperature and is adjusted to 40 C as follows inEquation 1:(Eq. 1)m40 a 0.0006840 ta()gcm3=_ SAE INTERNATIONAL J968-2 SEP2015 3 of 64.3.2 The following supply conditions shall be maintained taking into account gauge error:a
19、. Temperature of fluid at inlet: 1 C;b. Inlet Pressure: 0.1 bar;c. Maximum cyclic fluctuation in inlet pressure: 1 bar.4.4 Correction ProcedureTo compensate for the effects of temperature, density, and viscosity, the empiricalformula in Equation 2 shall be used:(Eq. 2)where: is the reference density
20、 = 0.808 g/cm3m40 is the fluid density (g/cm 3) in the circuit at 40 C is the reference dynamic viscosity = 2.1 x 103 Ns/m 2m40 is the dynamic viscosity (Ns/m 2) of fluid in the circuit at 40 C is the coefficient of volumetric expansion of the fluid, equal to 0.000824 C1tm is the fluid temperature (
21、C) in the flow measuring deviceta is the fluid temperature (C) at which density is measuredandK = 88 for 0.4 orificesK = 100 for 0.5 orificesK = 114 for 0.6 orificesK = 135 for 0.7 orificesK = for 0.8 orificesPREPARED BY THE SAE DIESEL FUEL INJECTION EQUIPMENT STANDARDS COMMITTEEFlowFlow measured()m
22、40-1.7 1m40 K-1 tm 40()+-=_ SAE INTERNATIONAL J968-2 SEP2015 4 of 6APPENDIX AAN OVERCHECK DEVICE FOR THE FLOW MEASURING SYSTEMOPTIONALA.1 RequirementsThe device as illustrated in Figure A1 shall have the following features:FIGURE A1SCHEMATIC DIAGRAM OF FLOW-CHECKING DEVICEA.1.1 Measuring Chamber (1)
23、The volume of the sample shall be measured in a chamber with the followingspecifications:a. 4 L capacity minimumb. Minimum internal wetted surfacec. Conical upper and lower surfacesd. Vertical graduated tube of 25 mm diameter maximum extending upwardly from the top surface of thechambere. Graduation
24、s in 1 mL increments and correct at 50 C to 2 mL after draining for 1 minf. Chamber made from low thermal expansion material, or appropriate allowance for differentialexpansion to be made in the measured flow correction formula (see 4.4)g. A 25 mm effective diameter drain valve in the center of the
25、baseh. Independent upwardly facing fluid inleti. The measuring chamber shall have a temperature sensor in a central position lying on the axis of theinlet connectionA.1.2 Level Sensor (2)A level sensor looking through the graduate shall stop the sample collection and timersimultaneously._ SAE INTERN
26、ATIONAL J968-2 SEP2015 5 of 6A.1.3 Three-Port Valve (3)A symmetrical power operated three-port valve with zero leakage (or two separatesimilar two-port valves operating in “push-pull“ mode) shall be arranged to connect the orifice outlet to eitherthe measuring cylinder or to a separate chamber havin
27、g the same height. This valve shall have anequivalent port area of between 6 and 8 mm diameter and shall have fast response time (50 ms) and equalin both directions.A.1.4 Slave Chamber (4)The second “slave“ chamber shall have an overflow at the same level as the sensor inA.1.2 (see Figure A1), and t
28、he measuring chamber shall have an overflow at a higher level.A.1.5 Drain Return (5)The drain return shall be separate from the overflow lines to ensure full and completedrainage.A.1.6 Control Unit (6)A control unit shall incorporate a second timer with a six figure display reading to threedecimal p
29、laces and having an accuracy of 0.001 s. Controls shall be provided to:a. Deliver the flow to the measuring chamber and start the timer simultaneouslyb. Drain and reset the timerc. Manually select and hold either direction of flow (to test for leakage)The sensor shall reverse the valve mode and stop
30、 the timer simultaneouslyA.1.7 Fluid Passageway (7)This fluid passageway, because it must run downward, shall have a bore size largeenough to produce no back pressure and small enough to carry entrained air downward with the smallestorifice flow rate, e.g., between 7 and 8 mm bore.A.2 Schematic Diagram Figure 1 shows the device for calibrating and checking a different type of faster actingprimary meter. The arrangement of overflow levels with respect to the orifice height and the arrangement ofthe fluid passageways shall be observed._ SAE INTERNATIONAL J968-2 SEP2015 6 of 6
