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Standard

Methods for Evaluating Cryogenic Filters

2019-12-03
CURRENT
ARP900C
The purpose of this document is to present test methods that can be utilized to evaluate the filtration and operating characteristics of filters that will be utilized in a cryogenic system. The methods presented herein are intended to supplement standard filter testing specifications to allow evaluation of filter performance characteristics in areas that could be affected by extreme low temperatures.
Standard

Filter Element Cleaning Methods

2019-07-15
WIP
AIR787B
This SAE Aerospace Information Report (AIR) provides technical information to assist the development of specific cleaning methods for filter elements. Consideration is limited to filter elements which are designated as "cleanable" (not "disposable"), but which cannot be cleaned by simple and obvious procedures. Cleaning methods developed according to this report should be evaluated by the methods of ARP725. Satisfactory cleaning methods can be developed for most "cleanable" filter elements. Technical or economic feasibility of the cleaning method may be limited, however, by incompatibility of filter-element construction materials, by mechanical weakness or lack of corrosion resistance to withstand repeated or continued cleaning, or by the presence of unusually tenacious contamination. These factors must be considered when selecting approaches to the development of specific methods.
Standard

Methods, Locations and Criteria for System Sampling and Measuring the Solid Particle Contamination of Hydraulic Fluids

2019-07-15
WIP
ARP5376C
This SAE Aerospace Recommended Practice (ARP) provides procedures for assuring cleanliness of sampling equipment, for performing the sampling process, and for measuring and reporting the sample particle count. The ARP specifies procedures for cleaning sample bottles, when used, and recommends the solvents to be applied and how these solvents should be prepared. Requirements for the selection of the sampling point, sampling method, and sampling frequency are also specified. This ARP also specifies three measuring methods for determining the level of solid particle contamination of hydraulic fluids used in aerospace hydraulics. These are: a. on-line automatic particle counting; b. automatic particle counting method using bottle samples; c. microscopic particle count method using bottle samples.
Standard

Aerospace - Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure

2018-08-13
CURRENT
ARP4285A
This SAE Aerospace Recommended Practice (ARP) establishes a method for evaluating the particulate matter extracted from the working fluid of a hydraulic system or component using a membrane. The amount of particulate matter deposited on the membrane due to filtering a given quantity of fluid is visually compared against a standard membrane in order to provide an indication of the cleanliness level of the fluid.
Standard

Bubble-Point Test Method

2017-04-04
CURRENT
ARP901B
This test method describes a procedure for measuring the largest pore or hole in a filter or similar fluid-permeable porous structure. A standard referee test method for precise determination or resolution of disputes is specified. A simpler inspection test procedure for quality assurance “go-no-go” measurement is also given. Bubble-point testing physics, analysis of bubble-point test data, and correlation with other methods of pore size determination are separately discussed in the appendix.
Standard

Aerospace Microscopic Sizing and Counting of Particulate Contamination for Fluid Power Systems

2016-06-09
CURRENT
ARP598D
This SAE Aerospace Recommended Practice (ARP) defines the materials, apparatus and procedure for sizing and counting of particulate contamination, 5 μm or greater, in hydraulic fluid samples by membrane filtration iwth microscopic counting. It is capable of counting particulate matter in samples withdrawn from fluid power systems as identified by the 12 classes of SAE AS 4059 or NAS 1638 and projected beyond these for the five standard ranges specified and can thus serve as the primary document to determine acceptability. It is also capable of revealing but not measuring evidence of abnormal amount of water, other fluids, fine particulate and other materials, especially fibers and metals. It is applicable to all military, civil, space vehicles and test equipment.
Standard

Evaluating Effectiveness of Filter Element Cleaning Methods

2014-06-03
CURRENT
ARP725B
This SAE Aerospace Recommended Practice (ARP) presents a procedure for evaluating cleaning methods with respect to contaminant removal and element degradation particularly for metallic filter elements. A procedure for checking durability of cleaning equipment and a referee cleaning method are also included. It is applicable only to the evaluation of cleaning methods proposed for removal of service dirt and not for built-in dirt, liquid oxygen (LOX) cleaning, etc. Supporting information for use with the ARP is also included.
Standard

Sensitization and Corrosion in Stainless Steel Filters

2014-02-06
CURRENT
AIR844B
This document reviews briefly the subject of woven metal screens. Conditions that can promote damaging corrosion in stainless steel filter screens are discussed and recommendations are listed for minimizing corrosion damage. This is a general document only; for specific applications it is suggested that the reader refer to the technical literature, and selected references listed below.
Standard

Aerospace Fluid Power - Contamination Classification for Hydraulic Fluids

2013-09-27
CURRENT
AS4059F
This SAE Aerospace Standard (AS) defines contamination classes and levels for particulate contamination of hydraulic fluids and includes methods of reporting related data (Appendix A). The contamination levels selected are based on the widely accepted NAS 1638 cleanliness classes. The conversion from NAS 1638 cleanliness class specifications to AS4059 class specifications is defined. The comparison of the NAS 1638 classes to AS4059 classes and levels is provided and are defined and the differences explained (Appendix B). NAS 1638 classes based on weight of particles are not applicable to these classes and are not included. A contamination code has been added to describe the contamination levels of the fluid at the specified particle size ranges.
Standard

Aerospace-Particle Count Data Conversion and Extrapolation

2012-09-24
CURRENT
AIR877C
This SAE Aerospace Information Report (AIR) describes a mathematical model that can be used to analyze particle count data. Particle counts that fit the model can be graphically displayed, converted from one counting size-frequency range to another, and extrapolated to estimate counts beyond the measured range. Derivation, applications, and calculations are described.
Standard

Secondary Filters for Fluid System Reliability

2012-09-24
CURRENT
AIR4057B
This SAE Aerospace Information Report (AIR) discusses the design choices and engineering trade-offs available to the system designer in the efficient selection and application of Last-Chance filters in contrast to main or primary system filters.
Standard

Fine Wire Mesh for Filter Elements

2012-09-24
CURRENT
AIR888C
This SAE Aerospace Information Report (AIR) discusses the terminology, types, method of manufacture and chemistry of the fine wire meshes used for filtration of hydraulic, lubrication fuel systems, and similar applications. Information contained herein may be used for quality assurance testing to insure that a high performance filter grade wire mesh is acceptable for use in an aerospace application.
Standard

Aerospace Microscopic Sizing and Counting of Particulate Contamination for Fluid Power Systems

2012-01-19
HISTORICAL
AS598
This SAE Aerospace Standard (AS) defines the materials, apparatus and procedure for sizing and counting of particulate contamination, 5 µm or greater, in hydraulic fluid samples by membrane filtration with microscopic counting. The microscopic counting method is capable of counting particulate matter in samples withdrawn from fluid power systems as identified by the 12 classes of AS4059 and projected beyond these for the five standard ranges specified and can thus serve as the primary document to determine acceptability. It is also capable of revealing but not measuring evidence of abnormal amount of water, other fluids, fine particulate and other materials, especially fibers and metals. It is applicable to all military, civil, space vehicles and test equipment.
Standard

Methods for Evaluating Cryogenic Filters

2011-12-19
HISTORICAL
ARP900B
The purpose of this document is to present test methods that can be utilized to evaluate the filtration and operating characteristics of filters that will be utilized in a cryogenic system. The methods presented herein are intended to supplement standard filter testing specifications to allow evaluation of filter performance characteristics in areas that could be affected by extreme low temperatures. The test methods can be utilized to evaluate filters for particle sizes equal to or greater than 5.0 μm and flows up to and including 60 gpm (230 L/min) capacity. If higher flow rate filters are to be evaluated in accordance with the test methods presented herein, it will be necessary to increase the system flow capacity and the size of effluent sampling system from those recommended in this document.
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