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 reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication m
3、ay 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: 724-776-4970 (outside USA)
4、 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/ARP5376B AEROSPACE RECOMMENDED PRACTICE ARP5376B Issued 1998-09 Revised 2010-03 Superseding ARP5
5、376A Methods, Locations And Criteria For System Sampling And Measuring The Solid Particle Contamination Of Hydraulic Fluids RATIONALE Revision B was made to correct and update references, and to make minor changes in the sampling procedures for clarity. INTRODUCTION General: The performance of moder
6、n hydraulic equipment for aerospace purposes is widely determined by the type and condition of the applicable hydraulic fluids. The quality and serviceability of these hydraulic fluids are dependent on various factors (e.g., thermal stability, viscosity), in particular on the level of solid particle
7、 contamination, which requires regular control if it is to be kept within the given limits. This recommended practice draws from aerospace industry experience and practice. It establishes recommended criteria for fluid contamination sampling and analysis of particulate contaminants in aerospace vehi
8、cle hydraulic systems. To obtain comparable test results, uniform test methods as given in this recommended practice should be used. Effects of Solid Particle Contamination: Solid particle contaminants have been linked to abrasive wear, contact fatigue, and fouling of critical passages, thereby shor
9、tening the life of the components in a hydraulic system. Solid particle contamination may have the following effects within a hydraulic system: a. components are subject to erosion (primarily in components with higher fluid velocities such as pressure control or servo valves); b. all moving parts ar
10、e subject to wear by abrasion; c. control valves are subject to silting (settlement of fine particles around the metering edges); d. critical passages may become blocked leading to functional failure. SAE ARP5376B Page 2 of 14Sources of Solid Particle Contamination: Solid particle contamination of h
11、ydraulic fluids may be system-generated, introduced from the outside, built-in during manufacturing or maintenance-generated, and may include but is not limited to: a. dust particles in the air; b. metal particles, produced during the manufacture of parts; c. sand residues on castings; d. abrasion o
12、f seals; e. oxide layers on welding seams and on heat-formed or heat-treated steel parts; f. chemical and physical changes in the condition of hydraulic fluids; g. maintenance of hydraulic systems (e.g., fibers from rags, contamination from component changeout, disassembly and assembly of fittings,
13、dirty quick disconnects on fluid servicing carts, adding new fluid from unclean containers, etc.); h. wear of components; i. ingress of particles via rod gland seals and wipers. Outline of This Recommended Practice: This recommended practice consists of four major parts: a. cleaning of apparatus and
14、 sample bottles, where used (Sections 3 to 6); b. sampling location, apparatus, collection methods, and frequency (Sections 7 to 10); c. analysis methods for solid particle contamination (Sections 11 to 13); d. data reporting (Section 14). 1. SCOPE This SAE Aerospace Recommended Practice (ARP) provi
15、des procedures for assuring cleanliness of sampling equipment, for performing the sampling process, and for measuring and reporting the sample particle count. The ARP gives procedures for cleaning sample bottles, when used, and recommends the solvents to be applied and how these solvents should be p
16、repared. Requirements for the selection of the sampling point, sampling method, and sampling frequency are also specified. This ARP also recommends three measuring methods for determining the level of solid particle contamination of hydraulic fluids used in aerospace hydraulics. These are: a. on-lin
17、e automatic particle counting; b. automatic particle counting method using bottle samples; c. microscopic particle count method using bottle samples. SAE ARP5376B Page 3 of 142. APPLICABLE DOCUMENTS The following publications form a part of this document to the extent specified herein. The latest is
18、sue 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 this document
19、, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1 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.sae.org. ARP598
20、Aerospace Microscopic Sizing and Counting of Particulate Contamination for Fluid Power Systems ARP4285 Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid Membrane Procedure AS4059 Aerospace Fluid Power - Cleanliness Classification for Hydraulic Fluids 2.2 ISO Publications Availab
21、le from International Organization for Standardization, 1 rue de Varembe, Case postale 56, CH-1121 Geneva 20, Switzerland, Tel: +41-22-749-01-1, www.iso.org. (Also available from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ISO
22、 3722 Hydraulic fluid power - Fluid sample containers - Qualifying and controlling cleaning methods ISO 4407 Hydraulic fluid power - Fluid contamination - Determination of particulate contamination by the counting method using an optical microscope ISO 11171 Hydraulic fluid power - Calibration of au
23、tomatic particle counters for liquids ISO 11500 Hydraulic fluid power - Determination of the particulate contamination level of a liquid sample by automatic particle counting using the light-extinction principle ISO 11943 Hydraulic fluid power - On-line automatic particle-counting systems for liquid
24、s - Methods of calibration and validation 3. GENERAL CLEANLINESS When establishing the level of solid particle contamination of hydraulic fluids, the test results may be adversely affected by not sufficiently taking account of the need for optimum cleanliness of the sampling and analysis equipment.
25、In order to obtain meaningful results reproducible at any place and at any time, it is essential to ensure that the preliminary conditions prevent any additional solid particle contamination of the hydraulic fluid sample taken. Additional solid particle contamination can be caused by using apparatus
26、 inadequately cleaned for the measurement. All apparatus used for sampling and determining the solid particle contamination level of hydraulic fluids should be thoroughly cleaned before use. The apparatus should be resistant to the solvent and the sample fluids. SAE ARP5376B Page 4 of 144. USE OF SO
27、LVENTS The following solvents are recommended for the cleaning procedure: a. Solvent A: De-mineralized, distilled or de-ionized water, or water from conversion osmosis. b. Solvent B: 2-propanol (isopropyl alcohol), reagent-pure. c. Solvent C: Petroleum ether or other suitable equivalents. WARNING: U
28、se precautions and consult applicable safety regulations when using flammable solvents. 5. FILTRATION OF SOLVENTS 5.1 Pressure Filtration Pressure filtration of solvents using an inert gas pressurized solvent tank is generally the most convenient method to dispense clean solvent. 5.1.1 Use the follo
29、wing typical apparatus: a. pressure tank, stainless steel; b. filter-jet spray gun, with filter attachment; c. membrane filter, having an aperture size less than or equal to 0.5 m. 5.1.2 Procedure The filter-jet spray gun (5.1.1b), with a membrane filter (5.1.1c) fitted, should be connected by a hos
30、e to the pressure tank (5.1.1a) containing the solvent. The gun should produce a concentrated jet of filtered solvent for cleaning the surfaces. Precleaning is not required. 5.2 Vacuum Filtration Vacuum filtration of solvents can be used as an alternative to pressure filtration, however, a final fil
31、ter using a membrane filter (5.2.1d) is still required on the dispensing wash bottle to ensure clean solvent is being dispensed. 5.2.1 Use the following typical apparatus: a. vacuum pump; b. filtration apparatus, stainless steel or glass; c. wash bottles; d. membrane filter, having an aperture size
32、less than or equal to 0.5 m. 5.2.2 Procedure For vacuum filtration of the solvent, the filtration apparatus (5.2.1b) should be fitted with a membrane filter (5.2.1d) and connected to the vacuum pump (5.2.1a) by a hose. The solvent should be filtered through the membrane filter by the vacuum in the f
33、lask of the filtration apparatus. The filtrate collected in the flask should be transferred to the correspondingwash bottle (5.2.1c). The wash bottle should only be used with a membrane filter (5.2.1d) fitted. SAE ARP5376B Page 5 of 146. SAMPLE BOTTLES Sample bottles, when used, should preferably be
34、 made from glass, should have a nominal capacity of 250 mL and a minimum capacity of 150 mL, and should be sealed by means of caps (preferably of phenolic resin) which will not cause contamination. Otherwise a non-flaking plastic film compatible with the hydraulic fluid should be used. Bottles made
35、of non-flaking polyethylene have also been used with success. 6.1 General Cleaning Requirements Before use, sample bottles and caps should be thoroughly cleaned in accordance with a qualified procedure such as the procedure described in 6.2. In carrying out steps d to f, care should be taken to ensu
36、re that the whole surface of the sample bottle is pressure-rinsed from top to bottom. Optionally, pre-cleaned sample bottles may be obtained from a qualified source adhering to the requirements below. 6.2 Recommended Cleaning Procedure for Sample Bottles The following method has been qualified to pr
37、oduce acceptable bottle cleanliness: a. rinse with a degreasing fluid; b. wash thoroughly in a filtered hot water solution of detergent; c. rinse twice with filtered hot water at a temperature of between 40 C and 60 C; d. rinse twice with solvent A, filtered through a membrane filter having an apert
38、ure size less than or equal to 0.5 m; e. rinse three times with solvent B, filtered through a membrane filter having an aperture size less than or equal to 0.5 m, to remove water; f. rinse three times with solvent C, filtered through a membrane filter having an aperture size less than or equal to 0.
39、5 m.After the last rinse, a small amount ( size 1 4 A 5 6 B 15 14 C 25 21 D 50 38 E 100 70 F Reported cleanliness class or classes: _ RequiredCleanliness: AS4059 class _ Based on size (A, B, or C) _ Other (describe) _ Technician comments (condition of sample, nature of contaminants, etc.): _FIGURE 3
40、 - TYPICAL FLUID CLEANLINESS REPORT SAE ARP5376B Page 13 of 1413. ANALYSIS METHOD USING A MICROSCOPE (BOTTLE SAMPLES) 13.1 Principle A known volume of fluid is filtered under vacuum conditions through a membrane filter with an imprinted grid to collect the solid particle contamination on the filter
41、surface. Using an optical microscope, counting and grouping of particles into size classes is done according to their largest dimension. The filter is rendered transparent for examination under transmitted light and left opaque for examination under incident light.13.2 Procedure Sample and membrane
42、preparation should be carried out in accordance with ARP4285 while particle counting should be carried out in accordance with ARP598 or ISO 4407. 13.3 Expression of Results The results should be expressed as the number of particles in each range per 100 mL of liquid. Record whether the microscopic e
43、xamination was performed under incident or transmitted light. See Section 14, Figure 3. 14. TEST REPORT 14.1 General The test report, as described in this recommended practice, should contain the results established by measuring the solid particle contamination of aircraft hydraulic fluids. The anal
44、ysis based on the test report permits the evaluation of the cleanliness of hydraulic fluids. Consequently, appropriate action can be taken in time to detect and correct deficiencies within the hydraulic system, which might be detrimental to its operation. 14.2 Test Report Form The facility carrying
45、out the measurement of the solid particle contamination of hydraulic fluids should complete the test report form in duplicate. The facility should keep one copy on file for technical documentation purposes and should return the other copy to the technical quality assurance group responsible for the
46、inspection of the aircraft. The minimum information to be included in the form is listed in 14.3. 14.3 Minimum Data to be Included in the Test Report The test report should include, as a minimum, the following information: a. sample identification (number, etc.); b. type of aircraft from which the s
47、ample has been taken; c. serial number of aircraft; d. aircraft system and location of sample; e. sampling date and time (relative to last flight); f. type or mix of hydraulic fluid (important for safety of handling); g. method of sampling and particle counting; h. the actual particle counts obtaine
48、d; SAE ARP5376B Page 14 of 14i. the analysis date; j. the name of the technician who carried out the measurement. A typical test report sheet is shown in Figure 3. 15. NOTES 15.1 A change bar ( l ) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. A
