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 there
2、from, 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 2013 SAE International All rights reserved. No part of this pu
3、blication 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: +1 724-776-4970
4、 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR887CAEROSPACEINFORMATION REPORT AIR887 REV. CIssued 1968-05 Revised 2008-06 Reaf
5、firmed 2013-10 Superseding AIR887B (R) Liquid Filter Ratings, Parameters and Tests RATIONALEAIR887C has been reaffirmed to comply with the SAE five-year review policy. TABLE OF CONTENTS 1. SCOPE 32. REFERENCES 32.1 Applicable Documents 32.1.1 SAE Publications. 32.1.2 U.S. Government Publications 32.
6、1.3 ISO Publications 43. GENERAL DATA ON ISO TEST DUSTS . 44. FILTER RATINGS. 44.1 Absolute Filtration Rating 44.2 Filtration Ratings . 44.2.1 Nominal Rating 54.2.2 Filtration Ratio. 54.3 Efficiency by Weight 75. SIGNIFICANT FILTER TESTS . 75.1 Clean Pressure Drop 75.2 Dirt Capacity 75.3 Collapse Pr
7、essure. 85.4 Flow Fatigue 85.5 Reverse Flow 95.6 Media Migration. 95.7 Material Compatibility 95.8 Cold Start Capability . 95.9 Contaminant Retentivity 96. FILTER ELEMENT TEST METHODS 96.1 Bubble Point Test 96.2 Maximum Particle Passed Test 106.3 Degree of Filtration Test . 106.4 Multi-pass Filter P
8、erformance Test. 116.4.1 Modified Multi-pass Tests . 116.5 Clean Element Pressure Drop Test 116.6 Dirt Capacity Test 12Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6.7 Collapse Test 126.8 Flow Fat
9、igue Test 126.9 Reverse Flow Test 126.10 Media Migration Test 136.11 Cold Start Test 136.12 Material Compatibility Test 136.13 Dynamic Efficiency Test 137. NOTES 14SAE INTERNATIONAL AIR887C Page 2 of 14_Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction o
10、r networking permitted without license from IHS-,-,-1. SCOPE This SAE Aerospace Information Report (AIR) identifies and explains the meaning of various ratings and terms used to describe the physical characteristics of liquid filter elements. The significance of various filter parameters is discusse
11、d. Inaddition, a number of filter test methods are briefly described. This AIR and the data presented are only applicable where the system liquid wets the filter elements. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. T
12、he 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 event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in t
13、his document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sa
14、e.org.ARP24 Determination of Hydraulic Pressure Drop ARP598 Aerospace Microscopic Sizing and Counting of Particulate Contamination for Fluid Power Systems ARP901 Bubble-Point Test Method ARP1827 Measuring Aircraft Gas Turbine Engine Fine Fuel Filter Element Performance AS4059 Aerospace Fluid Power -
15、 Cleanliness Classification for Hydraulic Fluids ARP4205 Aerospace Fluid Power - Hydraulic Filter Elements - Method for Evaluating Dynamic Efficiency with Cyclic FlowARP5454 Multi-Pass Method for Evaluating Filtration Performance of Fine Lube Filter Elements Utilized in Aerospace Power and Propulsio
16、n Lubrication Systems AIR5455 Impact of Changes in Test Dust Contaminants and Particle Counter Calibration on Laboratory Filter Element Performance and Fluid Cleanliness Classes 2.1.2 U.S. Government Publications Available from the Document Automation and Production Service (DAPS), Building 4/D, 700
17、 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 215-697-6257, http:/assist.daps.dla.mil/quicksearch/.MIL-F-8815 Filter and Filter Elements, Fluid Pressure, Hydraulic Line, 15 Micron Absolute and 5 Micron Absolute, Type II Systems General Specification For MIL-PRF-5606 Hydraulic Fluid, Petroleum B
18、ased MIL-PRF-83860 Filter Elements, Disposable, Fluid Pressure, Hydraulic Line, 5 Micron Absolute SAE INTERNATIONAL AIR887C Page 3 of 14_Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2.1.3 ISO Publ
19、ications Available from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org.ISO 12103-1 Road Vehicle - Test Dust for Filter Evaluation - Part 1 - Arizona Test Dust ISO 16889 Hydraulic Fluid Power - Multi-pass Method for Evaluating Filt
20、ration Performance of a Filter Element 3. GENERAL DATA ON ISO TEST DUSTS The new International Standard Organization (ISO) test dusts are manufactured from the same Arizona Road Dust as AC fine test dust (ACFTD), but processed with a jet mill and classified into well-controlled particle size distrib
21、utions. Suspensions of the ISO medium test dust are certified by National Institute of Standards especially in the 3 to 10 m range, than will the element rated 10 20. A number of filtration ratings can be based on the filtration ratio. Some of the more common of these ratings are as follows: 4.2.2.1
22、 Minimum Beta Ratio The minimum value of the filtration ratio for specified particle sizes during the filtration ratio test. 4.2.2.2 The Average Beta Ratio Since the filtration ratio may vary with differential pressure and from one sample point to the next, an average of the measured filtration rati
23、os for particles greater than any size of interest is used rather than the minimum value. The average beta ratio is calculated in accordance with ISO 16889. SAE INTERNATIONAL AIR887C Page 6 of 14_Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or netwo
24、rking permitted without license from IHS-,-,-4.2.2.3 The Time Averaged Beta Ratio Since there is a time base for the test, a time averaged filtration ratio is sometimes used. Either time averaged beta ratios or time averaged efficiencies can be used, but the results are not the same. Currently, the
25、most favored time average is based on the efficiencies. 4.3 Efficiency by Weight A number of Military Specifications, such as MIL-F-8815 and MIL-PRF-83860, require that a filter element remove a minimum percentage by weight of a specified contaminant when a certain weight of the contaminant is added
26、 on the upstream side of the element. This is known as a Degree of Filtration Test (see 6.3). While the test is very repeatable it has the disadvantage of measuring the efficiency of an element only at the beginning of its life. 5. SIGNIFICANT FILTER TESTS In addition to the filtration ratings the v
27、arious tests that are used to further determine the performance of an element are: a. Clean pressure drop b. Dirt capacity c. Collapse pressure d. Flow fatigue e. Reverse flow f. Media migration g. Material compatibility h. Cold start capability i. Contaminant retentivity 5.1 Clean Pressure Drop Cle
28、an pressure drop is the differential pressure across a new filter element at specified flow rates and temperatures with a specified fluid. As a specification requirement, clean pressure drop provides little measure of filter element service life compared to the dirt holding capacity to a specified t
29、erminal drop. See 6.5 for the test method. 5.2 Dirt Capacity The dirt capacity of a filter element relates to the frequency of maintenance, filter element change out intervals, and these relate to the economy of operation. The selection for a required dirt capacity for a filter element for a particu
30、lar flow-rate and filtration rating must be based on a trade-off study between size and economy. The Dirt capacity is the amount of contaminant added in a laboratory test to attain a filter element differential pressure corresponding to the change-out differential pressure for a specific application
31、. The filter element differential pressure, on which dirt capacity is based, is usually the setting at which the differential pressure indicator actuates. In the absence of an indicator, other parameters may be used, as shown below: SAE INTERNATIONAL AIR887C Page 7 of 14_Copyright SAE International
32、Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a. The pressure drop just below the cracking pressure of the housing bypass valve. b. An arbitrarily selected value below the collapse strength of the filter element; a typical le
33、vel being 3 to 9% of system operating pressure. In this case it should be verified that the filter element construction allows for filter performance to the stipulated differential pressure. In dirt capacity tests, increments of a standard contaminant are added continuously (ISO 16889) or periodical
34、ly (MIL-F-8815) until a specified differential pressure is reached. See 6.6 for a more detailed description of the procedure. The total contaminant added is called the apparent dirt capacity of the filter element. The retained dirt capacity is the amount of contamination retained by the filter eleme
35、nt during the test. The difference between the two dirt capacities is the amount of contaminant that passes through the filter element. Dirt capacity tests are sensitive to several test variables such as contaminant characteristics, rate and amount of contaminant added, fluid, temperature, flow rate
36、 and system conditioning (volume, cleanup filter, etc.). ISO test dusts (per ISO 12103-1), which simulate natural airborne dust, are commonly used for dirt capacity testing. Different contaminants will yield different capacities for the same filter elements. While other contaminants can be used, the
37、 ISO dusts provide standardized contaminants at relatively low cost. The ISO 12103-1 test dusts are categorized into four grades based on their particle distributions.A1: ultrafine A2: fine A3: medium A4: coarseOne basic difference in commonly used dirt capacity tests is whether or not a cleanup fil
38、ter is permitted downstream of the test filter element during testing. The use of a cleanup filter will increase the apparent dirt capacity. The lower the filtration efficiency of the element, the greater the increase in apparent dirt capacity of the element. However, if use of a cleanup filter is n
39、ot permitted, the volume and design of the test circuit can have an effect on the apparent dirt capacity and influence the repeatability of the test with different test stands. In addition to the Dirt Capacity, filter element service life is also related to contamination generation within the system
40、 andingestion rates. Contamination generation is related to filter element efficiency since high efficiency filter elements providecleaner systems that result in less wear and contamination generation. 5.3 Collapse Pressure The collapse pressure is the maximum differential pressure that the filter e
41、lement can withstand without filtration medium or structural failure. The minimum collapse pressure must exceed the filter bypass relief valve setting to allow for full flow pressure drop at cold temperature. For a filter without a bypass relief valve the minimum collapse pressure should be higher t
42、han the maximum differential pressure that can be developed across the filter element during system operation; see 6.7 for a collapse pressure test method. For instance, high pressure filter elements designed in accordance with MIL-F-8815 are required to meet a collapse pressure 1.5 times the system
43、 operating pressure. 5.4 Flow Fatigue Flow fatigue tests determine the integrity of the filter element to withstand pulsating flow by subjecting the element to a flow cycle that normally ranges from zero to a specified percentage of rated flow and back to zero. Test dust is added so that cycles are
44、conducted at specified differential pressure(s). The number of flow cycles and differential pressure specified for testing should be dependent upon the expected service life and operating conditions. See 6.8 for test procedure.SAE INTERNATIONAL AIR887C Page 8 of 14_Copyright SAE International Provid
45、ed by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5.5 Reverse Flow In some systems, the filter element may be subjected to reverse flow, i.e., fluid flow through the filter housing is in a direction which is the reverse of the normal f
46、low direction. Reverse flow capability can be designed into a filter element by the use of support screens or mesh on both sides of the medium. Often a better alternative is to design the housing to allow the reverse flow condition to bypass the filter element. Also with an appropriate reverse-flow
47、bypass valve, the housing can be designed so the direction of the flow through the filter element is always the same regardless of direction of flow though the housing. See 6.9 for the test procedure. 5.6 Media Migration Media migration tests are specified to determine, and hence, limit, the amount of filtration medium or other materials of construction that are released from the fil
