ASTM D4174-89(2005)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4174 – 89 (Reapproved 2005)
Standard Practice for
Cleaning, Flushing, and Purification of Petroleum Fluid
Hydraulic Systems
This standard is issued under the fixed designation D4174; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
Section
Supplementary Methods 6.3.3
1.1 Thispracticecoversaidfortheequipmentmanufacturer,
Limitations of Contamination Control Devices 6.3.4
the installer, the oil supplier and the operator in coordinating
Storage 7
General 7.1
their efforts towards obtaining and maintaining clean petro-
Inspection 8
leum fluid hydraulic systems. Of necessity, this practice is
General 8.1
generalized due to variations in the type of equipment, build-
System Components 8.2
Valves, Strainers and Coolers 8.2.1
er’s practices, and operating conditions. Constant vigilance is
Sumps and Tanks 8.2.2
required throughout all phases of design, fabrication, installa-
Control Devices 8.2.3
tion, flushing, testing, and operation of hydraulic systems to Pumps 8.2.4
Flushing Program 9
minimize and reduce the presence of contaminants and to
General 9.1
obtain optimum system reliability.
Preparation of System for Flushing 9.2
1.2 This practice is presented in the following sequence: Oil Heating Prior to Flushing 9.3
Selection of Flushing Oil 9.4
Section
System Operation Oil 9.4.1
Scope 1
Special Flushing Oil 9.4.2
Referenced Documents 2
Flushing Oil Selection Guide 9.4.3
Significance and Use 3
Flushing Procedure for New Systems 9.5
Definitions 4
Flushing Oil Charge 9.5.1
Types of Contamination 5
Cleaning of Filtration Devices 9.5.2
General 5.1
Cleaning of System Components 9.5.3
Water 5.2
System Flushing 9.5.4
Soluble Contaminants 5.3
Draining of Flushing Oil 9.5.5
Insoluble Contaminants 5.4
Displacement Oil 9.5.6
Lodged Contamination 5.4.2.1
Interim Corrosion Protection 9.5.7
Suspended Contamination 5.4.2.2
New Fluid Charge 9.5.8
Contamination Control 6
Flushing of Used Systems 9.6
General 6.1
General Guidelines 9.6.1
Initial Filling 6.1.1
Procedure 9.6.2
In-Service Units 6.1.2
System Maintenance 10
Connection of Contamination Control System 6.1.3
Shipping 10.1
Piping to Contamination Control System 6.1.4
Preinstallation 10.2
Contamination Control Procedures 6.2
In-Service Units 10.3
Full Flow Contamination Control 6.2.1
Decision to Flush In-Service Hydraulic Systems 10.4
Bypass Contamination Control 6.2.2
Fluid Condition Monitoring 11
Batch Contamination Control 6.2.3
Fluid Sampling Techniques 11.2
Contamination Control Processes 6.3
Visual Inspection 11.3
Gravity 6.3.1
Laboratory Analysis 11.4
Mechanical 6.3.2
Fluid Cleanliness Criteria 11.5
Centrifuge 6.3.2.1
General Information 12
Filters 6.3.2.2
Filter Ratings 12.2
Centrifuge Ratings 12.3
Coalescence 12.4
Vacuum Dehydration 12.5
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
Adsorption 12.6
Products and Lubricants and is the direct responsibility of D02.N0 on Hydraulic
Fluids.
1.3 The values stated in SI units are to be regarded as the
Current edition approved May 1, 2005. Published May 2005. Originally
standard. The values given in parentheses are for information
approved in 1982. Last previous edition approved in 1999 as D4174 – 89 (1999).
DOI: 10.1520/D4174-89R05. only.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4174 – 89 (2005)
1.4 This standard does not purport to address all of the cleaned to a level that will prevent component damage on
safety concerns, if any, associated with its use. It is the initial start up or when debris may be dislodged by any system
responsibility of the user of this standard to establish appro- upset.
priate safety and health practices and determine the applica- 4.2 The cleaning and flushing of both new and used systems
bility of regulatory limitations prior to use. are accomplished by essentially the same procedure. In new
systems, the emphasis is on the removal of contaminants
2. Referenced Documents introduced during the manufacture, storage, field fabrication,
and installation. In used systems, the emphasis is on the
2.1 ASTM Standards:
removal of contaminants that are generated during operations,
D445 Test Method for Kinematic Viscosity of Transparent
from failures that occur during operation; or contaminants
and Opaque Liquids (and Calculation of Dynamic Viscos-
introduced during overhaul.
ity)
4.3 While the flushing and cleaning philosophies stated in
D664 Test Method forAcid Number of Petroleum Products
this practice are applicable to all primary and servo hydraulic
by Potentiometric Titration
systems, the equipment specified herein does not apply to
D974 Test Method for Acid and Base Number by Color-
compact systems that use relatively small volumes of fluid
Indicator Titration
3 unless they are servo systems where it is economically justi-
D1774 Test Method for Elastic Properties of Textile Fibers
fied.
D2709 Test Method for Water and Sediment in Middle
4.4 It should be emphasized that the established procedures
Distillate Fuels by Centrifuge
to be followed for flushing and cleaning the hydraulic systems
D4006 Test Method for Water in Crude Oil by Distillation
should be accomplished through the cooperative efforts and
F311 Practice for ProcessingAerospace Liquid Samples for
agreement of the equipment manufacturer, the installer, the
Particulate Contamination Analysis Using Membrane Fil-
operator, and the fluid supplier. No phase of these procedures
ters
should be undertaken without a thorough understanding of the
F312 Test Methods for Microscopical Sizing and Counting
possible effects of improper system preparation. The installa-
Particles from Aerospace Fluids on Membrane Filters
tion and cleaning and flushing of the equipment should not be
F313 Test Method for Insoluble Contamination of Hydrau-
entrusted to persons lacking in experience.
lic Fluids by Gravimetric Analysis
2.2 ANSI Standards:
5. Types of Contamination
B93.2 Glossary of Terms for Fluid Power
5.1 General—Hydraulic systems can become contaminated
B93.19 Method for Extracting Fluid Samples from the
fromavarietyofsources.Generally,therearefivecategoriesof
Lines of an Operating Hydraulic Fluid Power System (for
contamination: (1) water, (2) fluid soluble material, (3) fluid
Particulate Contamination Analysis)
insoluble material, (4) erroneous fluid additions, and (5)
hydraulic fluid deterioration. Properly designed systems can
3. Terminology
normally control water and insoluble contaminants; however,
3.1 Definitions:
when it is necessary to remove soluble contaminants, a fluid
3.1.1 absolute filtration rating—the diameter of the largest
change and flush are required.
hard spherical particle that will pass through a filter under
5.2 Water—Water is almost always present in hydraulic
specified test conditions. This is an indication of the largest
fluids. It may be present in solution or in a free or emulsified
opening in the filter element.
form. Water can exist in solution at varying concentrations
3.1.2 nominal filtration rating—an arbitrary micrometre
depending on the nature of the fluid, the temperature, and so
value indicated by a filter manufacturer. Due to lack of
forth. For example, hydraulic fluid may hold 50 ppm of water
reproducibility this rating is deprecated. (ANSI B93.2)
at 21°C (70°F) and 250 ppm at 71°C (160°F). The water in
solution has no adverse effect on lubricating properties of the
4. Significance and Use
fluid and causes no corrosion; however, when fluid passes
4.1 Proper fluid condition is essential for the satisfactory
through a cooler some water may come out of solution and
performance and long life of the equipment. Prerequisites for
become free water in the form of finely dispersed droplets.
proper lubrication and component performance are: (1)a
Many contaminants hinder the separation of this free water
well-designedhydraulicsystem,(2)theuseofagoodfluid,and
from the fluid by settling and may cause an emulsion. In
(3) a maintenance program including proper filtration methods
hydraulic fluids, the emulsion impairs circulation, interfere
to ensure that the fluid is free of contaminants. These prereq-
with lubrication and adversely affect contamination control
uisites are meaningless unless the hydraulic system is initially
equipment.
5.2.1 Water contamination can be classified as either fresh
or sea water, as encountered in land or marine systems. Fresh
2 water enters the hydraulic system from moist air as condensa-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
tion, through improperly located vents, leaks in coolers, and
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
steamheaters,andbecauseofimproperoperation.Seawater,in
the ASTM website.
marine hydraulic systems, enters through leaks in coolers,
Withdrawn.
faulty manhole gaskets, faulty sump tank seals and improperly
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036. located vents. Sea and brackish water can also present a
D4174 – 89 (2005)
problem when used as a coolant in land-based units. Water 5.4.2.1 Lodged Contamination—These contaminants may
contamination in hydraulic fluids can: become dislodged by high fluid flows and temperature differ-
entials or by induced vibration during flushing. Contamination
5.2.1.1 Promote fluid oxidation.
can be lodged in unflushed pockets or settled on the bottom of
5.2.1.2 Reduce fluid stability.
tanks. Unless this contaminant is removed, it becomes dis-
5.2.1.3 Promote sludge.
lodged during startup or during system upsets. Experience,
5.2.1.4 Promote foaming.
good judgement, and careful inspection by the installation
5.2.1.5 Form emulsions.
supervisormustbereliedupontodeterminewhensuchdirthas
5.2.1.6 Promote rusting and corrosion.
been satisfactorily removed.
5.2.1.7 Affect additive and concentration.
5.4.2.2 Suspended Contamination:
5.2.1.8 Adversely affect lubricating properties.
5.4.2.3 (a) Contaminants suspended in the fluid can be
5.2.1.9 Promote bacteria growth.
generated by particles coming loose from pipe, hose, hydraulic
5.2.1.10 Alter fluid viscosity.
components,tankwallsgenerallycausedbyhighfluidvelocity,
5.2.1.11 Adversely affect fine filtration.
wear debris, and vibration. Suspended contaminant can be
5.2.2 In the case of severe salt water contamination, it is
measured, as described in 11.3. To prevent the level of
necessary to remove the operating fluid and clean and flush the
suspended contaminant from getting beyond acceptable limits,
hydraulic systems.
all units should be provided at least with a bypass contamina-
5.3 Soluble Contaminants:
tion control system (fluid filter or centrifuge). Preferably a full
5.3.1 Soluble contaminants in hydraulic systems include
flow filter or a full flow filter plus bypass purification is
cleaning chemicals, solvents, rust preventives, incompatible
provided. When a full flow filter is used, a bypass purification
lubricants, flushing oils, extraneous oils, oxidation products,
system may not be required.
gasket sealants, and assembly lubricants. These contaminants
5.4.2.4 (b) The bypass or full flow system, or both, are in
cannotberemovedbyconventionalfluidcontaminationcontrol
operation during the flush operation as well as on a continuous
equipment. Normally, a new charge of fluid is required to
basis during hydraulic system operation. The rated flow capac-
correct the problem. Fluid soluble contaminants can:
ity per hour of a bypass system should be 10 to 20 % of the
5.3.1.1 Change the fluid viscosity.
total system fluid volume.
5.3.1.2 Alter the flash point.
6. Contamination Control
5.3.1.3 Change the color.
6.1 General—Contamination control in a hydraulic system
5.3.1.4 Result in sludge deposits.
is the complete program of monitoring and maintaining a clean
5.3.1.5 Attack elastomeric seals.
fluid. Contamination control must begin with the design,
5.3.1.6 Initiate additive-water interaction that can cause
manufacture, and installation of the hydraulic system and
emulsification, possible additive loss, instability, impaired
continue throughout the life of the system. When making
purification equipment performance, foaming, and air entrain-
inspections or working in or around a unit, care must be taken
ment.
to prevent contaminants from entering the system. When work
5.3.1.7 Accelerate oxidation.
that generates contaminants is being performed in the vicinity
5.3.2 When a soluble contaminant is present, the fluid
of the hydraulic system, the system components must be
supplier and consult the equipment manufacturer should be
protected even to the extent of suspending operations, and
consulted regarding the advisability of continued use of the
requiring system components to be sealed until the contami-
fluid or replacing it with a new charge.
nating activity has ceased. The contamination control system
5.4 Insoluble Contaminants:
must be capable of removing water and particulate matter
5.4.1 Insoluble contaminants normally encountered are
consistentwithcontaminationtoleranceandsystemcleanliness
metal particles of all types and sizes, fibers, airborne solids,
requirements.
sand, and other nonmetallic particles. These contaminants are
6.1.1 Initial Filling—When initially filling the hydraulic
often the result of improper manufacturing techniques, im-
system, all fluids are filtered through 3 to 10-µm absolute (see
proper shipping and storage practices, and careless installation
4.1) filters as they are being transferred into the reservoir. The
of hydraulic systems. Some of the effects of solid contamina-
contaminationcontrolsystemisreadyforoperationpriortothe
tion are:
hydraulic system fill and is operating throughout flushing. See
5.4.1.1 Abrasive wear or sticking of components such as:
Section 9.5.
control valve poppets, cylinders, piston rods, and seals.
6.1.2 In-Service Units—The contamination control system
5.4.1.2 Faulty control functioning, particularly plugged
is in operation as long as the hydraulic system is in service. Its
fluid lines/filter plugging.
operationisfrequentlyandregularlymonitoredtoassurethatit
5.4.1.3 Reduced fluid stability.
is performing adequately and to determine the need for its
5.4.1.4 Sludge formation.
maintenance.
5.4.1.5 Increased foaming tendency.
6.1.3 Connection of Contamination Control System—The
5.4.1.6 Stabilized water-oil emulsions/accelerated oxidation
external fluid take-off from the circulating syst
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