GB/T 46719.3-2026Aerospace - Hydraulic filter elements test methods - Part 3: Filtration efficiency and retention capacity (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document is Part 3 of GB/T 46719 "Test Methods for Aerospace Hydraulic Filter Elements". GB/T 46719 has been published as follows.

Part 2.

---Part 1: Experimental Sequence;

---Part 2: Regulatory Role;

---Part 3: Filtration Efficiency and Retention Capacity;

---Part 4: Validation of Crushing/Rupture Pressure Rating;

---Part 5: Resistance to Flow Fatigue;

---Part 6: Cleanliness Levels this document is modified to adopt ISO 14085-3:2024 "Aerospace series hydraulic filter elements - Test methods - Part 3: Filtration efficiency and cut-off".

Retaining ability.

This document differs significantly from ISO 14085-3:2024.The relevant clauses are indicated in vertical margins.

Straight lines (|) are marked. A summary of these technical differences and their reasons can be found in Appendix A.

The following editorial changes have been made to this document.

---To align with existing standards, the standard title has been changed to "Test Methods for Aerospace Hydraulic Filter Elements - Part 3: Filtration Efficiency and..." "Interception Capacity"

---The pressure difference symbol "deltap" has been removed from section 3.3;

---The description of index number 2 in Figure 2 has been changed, replacing "filter element ultimate pressure difference" with "net pressure difference";

---Added table titles to the tables in Chapter 4 and named them "Table 1 Letter Symbols";

---Added the letter symbols "m2.5%" and "m80%" from Chapter 4;

---The serial numbers of Tables 1 to 5 in the file have been changed to Tables 2 to 6;

---The notation for the upstream basic weight contamination predefined value in 10.2.2 has been changed from "c'i" to "c'b";

---The notation for the initial volume of the sludge injection system in version 10.2.8 has been changed from "Vii" to "Vi";

---The symbol for the test flow rate in 11.2.1 has been changed from "qt" to "qf";

---The symbol for the predefined sewage injection flow rate in 11.2.9 has been changed from "c'i" to "q'i";

---The sign for the average upstream basic weight contamination level in 12.1.12 has been changed from "c'b" to "cb";

---The symbol in formula (19) has been changed, replacing "qi" with "qi";

---The symbol in the note in 12.1.14 has been changed from "c'b" to "cb";

---The description of the record location in section 12.2 has been changed from "recorded in Tables 4 and 5" to "recorded in Table 6";

---The symbols in formulas (25) and (26) have been changed, with "c2.5%" changed to "m2.5%" and "c80%" changed to "m80%".

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed and is under the jurisdiction of the National Aircraft Standardization Technical Committee (SAC/TC435).

Introduction

GB/T 46719 aims to provide a unified and consistent procedure for performance testing of aerospace hydraulic filter elements, and is proposed to consist of six parts.

---Part 1: Test Sequence. The purpose is to specify the test sequence and provide guidelines for acceptance criteria.

---Part 2: Regulation. This section describes the filter element's thermal conditions and cold start test procedure.

---Part 3: Filtration Efficiency and Retention Capacity. This section describes the test procedures for the filtration efficiency and retention capacity of filter cartridges.

---Part 4: Crushing/Rupture Pressure Rating Verification. This section describes the crushing/rupture pressure testing procedure for filter elements.

---Part 5: Resistance to Flow Fatigue. The purpose is to describe the test procedures for the filter element's resistance to flow fatigue.

---Part 6: Cleanliness Class. This section describes the test procedures for the initial cleanliness of the filter element.

In aerospace hydraulic fluid power systems, power is transmitted and controlled through pressurized fluid. This fluid serves as both a lubricant and a...

It is the power transmission medium. The presence of solid contaminant particles in the liquid can interfere with the lubrication ability of the hydraulic oil and lead to wear and failure of components.

The degree of contamination in the fluid directly affects the system's performance, reliability, and safety, and needs to be controlled within the system's permissible level.

There are several methods to control system contamination levels by removing solid contaminants, one of which is to use a filter cartridge encapsulated in a housing.

Filter cartridges achieve filtration through porous media. A filter is a complete device used to achieve system filtration.

The performance characteristics of a filter depend on the filter element (its media and geometry) and the housing (its overall structure and sealing design). For specific...

The actual performance of a filter is also related to fluid characteristics (viscosity, temperature, conductivity, etc.), suspended particles (size, shape, hardness, etc.), and flow conditions.

Related to the item.

A standard multi-pass method for evaluating the filtration performance of hydraulic filter elements under stable flow conditions has been developed and used for many years, and it has been cited in the hydraulic system specifications of many aircraft.

Most hydraulic fluid systems experience flow pulsations, a state of unstable flow, due to actuator actions and other factors.

This will have a significant impact on filter performance. To select the most suitable filter, it is necessary to compare the relative performance of different filters. To ensure this...

The reliability of the comparison needs to be tested under the same standard operating conditions.

This document describes two test methods and the required equipment for evaluating the performance of hydraulic filter elements under both stable and fluctuating flow conditions.

This document cannot measure the effects of other harsh operating conditions (such as high temperature, low temperature, and vibration) alone. Before conducting efficiency tests, the effects were assessed through...

The test filter element is pretreated (the description of these operating conditions and the order of the tests is in GB/T 46719.1) to determine the effects of these operating conditions.

The stable contamination level measured under fluctuating flow conditions indicates the average contamination level maintained by the filter in a dynamic operating system.

Contamination level is important for determining wear rate and reliability level.

During the experiment, operating conditions, especially the test medium and contaminants, were precisely controlled to ensure repeatability and reproducibility. Due to the experiment...

The parameters and test contaminants cannot accurately reproduce actual operating conditions (actual operating conditions vary significantly between different systems), so the results cannot be expected to accurately reflect real-world conditions.

The results are completely consistent with the actual performance of the working system.

Aerospace hydraulic filter element test methods Part 3: Filtration Efficiency and Retention Capacity

1 Scope

This document describes the test equipment, instrument accuracy and test conditions, test equipment verification, and test procedures for the performance testing of aerospace hydraulic filter elements.

Information required before testing, pre-test preparation, filter efficiency test, data processing and recording, labeling instructions, etc.

This document is applicable to evaluating the filtration performance of aerospace hydraulic filter elements under conditions of stable and fluctuating flow rates.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

GB/T 14041.1 Hydraulic filter elements – Part 1: Verification of structural integrity and determination of initial bubble point (GB/T 14041.1-2007, ISO 2942:2004, IDT) GB/T 17446 Glossary of Fluid Transmission Systems and Components (GB/T 17446-2024, ISO 5598:2020, MOD) GB/T 17486 Evaluation of differential pressure and flow characteristics of hydraulic filters (GB/T 17486-2006, ISO 3968:2001, IDT) GB/T 17489 Particulate Contamination Analysis of Hydraulic Transmission Systems—Extraction of Liquid Samples from Working System Piping (GB/T 17489-2022) ISO 4021:1992, MOD) GB/T 18854 Calibration of hydraulically driven automatic particle counters (GB/T 18854-2015, ISO 11171:2010) MOD) GB/T 21540 Calibration and Validation Methods for Hydraulic Transmission Online Liquid Automatic Particle Counting System (GB/T 21540-2022) ISO 11943:2018, MOD) GB/T 27613 Determination of particulate contamination in hydraulic transmission fluids by gravimetric method (GB/T 27613-2011, ISO 4405.

1991, MOD)

ISO 12103-1:2024 Test dust for evaluating filters in road vehicles - Part 1: Arizona test dust Note. GB/T 28957.1-2023 Test dust for evaluating filters in road vehicles - Part 1: Test dust for silica (ISO 12103-1.

2016, MOD)

3 Terms and Definitions

The terms and definitions defined in GB/T 17446 and the following terms and definitions apply to this document.

The total amount of a specified particulate contaminant injected into the test system when the ultimate pressure differential is reached.

Flow pulsation cyclic flow at the specified frequency and waveform, the flow rate changes from the rated flow rate to 25% of the rated flow rate.