WIXLIB

ALFAGOMMA // HOSE GUIDELINESSAFETY GUIDE AND BASIC FACTORS FOR THE SELECTION, INSTALLATION AND MAINTENANCEOF HOSE AND HOSE ASSEMBLIESALFAGOMMA10Hydraulic hose (and hose assemblies) has a limited lifedependent on service conditions to which is applied.Subjecting hose (and hose assemblies) to conditions moresevere than the recommended limits significantly reduceservice life. Exposure to combinations of recommendedlimits (i.e., continuous use at maximum rated workingpressure, maximum recommended operating temperatureand minimum bend radius) will also reduce service life.Laminar flow - In laminar flow, the individual fluid particlesmove up to certain speeds in uniform layers alongside eachother. They scarcely disturb or influence each other.Turbulent flow - If the value for Re exceeds 2300, flowbecomes whirling and turbulent. The individual particlesno longer move in one direction in an orderly fashion, butinfluence and hinder each other.WARNING: FAILURE TO FOLLOW PROPERSELECTION, INSTALLATION AND MAINTENANCEPROCEDURES MAY RESULT IN PREMATUREFAILURES, BODILY INJURY, AND DAMAGE TOPROPERTY.LAMINAR1. SELECTION - The following is a list of factors which mustbe considered before the selection of a hose can be made:TURBULENT1.1 Line sizeIn order to achieve maximum efficiency in a hydraulic system,it is necessary to keep pressure losses (resistance to thevolumetric flow) to a minimum when a fluid is conveyed bythe different types of flow lines.When a fluid flows through a flow line, heat is generated byfriction. Thus part of the energy is lost as heat energy, whichresults in a pressure loss.These pressure losses depend upon: flow velocity (for a given volumetric flow, the fluid flowvelocity increases with a decrease in the cross sectionalarea of a flow line and vice versa) length of the flow line the viscosity of the fluid flowing the density of the fluid flowing the type of flow (laminar or turbulent)Types of flow - The type of flow changes from laminar toturbulent at a certain flow velocity. This velocity is givenby the Reynold’s Number Re.For cylindrical flow lines the following formula applies:Re vxdυwhere: v velocity (m/s)d flow line internal dia (m)υ kinematic viscosity (m2/s)As soon as the value for Re exceeds 2300, the laminar flowchanges to turbulent flow.www.alfagomma.comCertain fluid flow velocities have proved to be most suitablefor hydraulic flow lines.Recommended flow velocities:Suction lines:0.5 1.2 m/sReturn lines:2 3 m/sPressure lines:4 7.5 m/s1.6 4 feet/s6.5 10 feet/s13 25 feet/sFLOW CAPACITY NORMOGRAMFlow Capacities of Hose at Recommended Flow VelocitiesThe chart below is provided as an aid in the determinationof the correct hose size.Example: at 45 l/min, what is the proper hose size withinthe recommended velocity range for pressure lines?Locate 45 l/min in the left-hand column and 7,5 m/s in theright-hand column (the maximum recommended velocityrange for pressure lines).Lay a straight line across these two points. The insidediameters shown in the centre column is above 9,5 mm sowe have to use 12,7 mm (1/2”). For suction hose, follow thesame procedure except use recommended velocity rangefor intake lines in the righthand column.where Q flow in liters per seconds (l/sec)V velocity in meters per seconds (m/s)d hose inside diameter (mm & dash size)

ALFAGOMMA // HOSE GUIDELINESTECHNICAL INFORMATION – NORMOGRAM OF THE FLOWFlow Ql/min11ALFAGOMMAThe normogram herewith is pivotal to help you find the hose diameter by knowing the liquid flow and speed.In order to find the correct diameter you should trace a line between the flow value (l/min) and the suggested speed (m/sec)according to the kind of delivery (pressure or return). The value touched by the line in the central column will indicate the hoseID (mm/inches) that must be used.Gal/min *Inside diameter ocity forsuction linesRecommendedmaximumvelocity forreturn linesRecommendedmaximumvelocity forpressure lines* gallons are UK gallonsConversion factor: gal/min x 4,546 l/minfeet/s x 0,3048 m/s

ALFAGOMMA // HOSE GUIDELINESALFAGOMMA12It is therefore important to calculate correctly the requiredflow line sizes. Undersized pressure lines results in highfluid velocity causing an excessive pressure drop, and heatbuilt up, which impair overall system performance.Undersized suction lines can cause cavitation at thehydraulic pump inlet, affecting performance, shorteningpump life, and creating excessive noise levels.The flow capacity normogram on page (12) is an aid todetermine the correct hose internal diameter size, desiredflow rate and recommended velocity. By the use of any twoknown factors, the third can be determined.1.2 Pressure:After determining the system pressure for a hydraulicsystem, hose selection must be made so that therecommended maximum operating pressure specified bya given hose, is equal or greater than the system pressure.Dynamic pressure is common for all hydraulic systems.Pressure surges which exceed the maximum workingpressure (pressure relief valve setting) affect the servicelife of system components, including a hose assembly andtherefore need to be taken into consideration. Hoses usedfor suction lines must be selected to ensure the hose willwithstand the negative pressure of the system.1.3 Temperature:Care must be taken to ensure that the operating temperatureof the fluid being conveyed and ambient temperatures, donot exceed the limitations of the hose.Special care must be taken when routing near hot manifoldsor molten metal.1.4 Fluid Compatibility:Hose selection must assure compatibility of the hose tube,cover, reinforcement, and fittings with the fluid used.Additional caution must be observed in hose selection forgaseous applications. Some fire resistant fluids require thesame hose as petroleum oil. Some use a special hose, whilea few fluids will not work with any hose at all.For gas application, where compatible with AlfagommaHoses, and at pressure above 10bar, the hose cover shallbe pin-pricked.1.5 Permeation:Permeation (that is, seepage through the hose) will occurfrom inside the hose to outside when hose is used withgases, liquid and gas fuels, and refrigerants (includingbut not limited to such materials such as helium, fuel oil,natural gas or freon). This permeation may result in highconcentrations of vapours which are potentially flammable,explosive, or toxic and in loss of fluid.Even though the fluid compatibilty is acceptable, you musttake into account the fact that permeation will occur and couldbe hazardous. Permeation of moisture from outside the hoseto inside the hose will also occur. If this moisture permeationwould have detrimental effects (particularly but not limited torefrigeration and air conditioning systems), incorporation ofsufficient drying capacity in the system or other appropriatesystem safeguards should be selected and used.1.6 Routing:Attention must be given to optimum routing to minimiseinherent problems. Restrain, protect or guide hose withthe use of clamps if necessary to minimise risk or damagedue to excessive flexing, whipping or contact with othermoving parts or corrosives. Determine hose lengthsand configurations that will result in proper routing andprotection from abrasion, snagging or kinking and provideleak resistant connections.www.alfagomma.com1.7 Environment:Care must be taken to ensure that the hose and fittings areeither compatible with or protected from the environment towhich they are exposed. Environmental conditions includingbut not limited to ultraviolet light, heat, ozone, moisture,water, salt water, chemicals, and air pollutants can causedegradation and premature failure and, therefore, must beconsidered.1.8 Mechanical Loads:External forces can significantly reduce hose life.Mechanical loads which must be considered includeexcessive flexing, twist, kinking, tensile or side loads, bendradius, and vibration. Use of swivel type fittings or adaptorsmay be required to ensure no twist is put into the hose.Unusual applications may require special testing prior tohose selection.1.9 Abrasion:While a hose is designed with a reasonable level of abrasionresistance, care must be taken to protect the hose fromexcessive abrasion which can result in erosion, snagging,and cutting of the hose cover. Exposure of the reinforcementwill significantly accelerate hose failure.1.10 Proper End Fitting:Care must be taken to ensure proper compatibility existsbetween the hose and coupling selected based on themanufacturer’s recommendations substantiated by testingto industry standards such as SAE J517DIN 20024, JIS B 8360.1.11 Length:When establishing proper hose length, motion absorption,hose length changes due to pressure, as well as hose andmachine tolerances must be considered.1.12 Specifications and Standards:When selecting hose and fittings, government, industry,and manufacturer’s specifications and recommendationsmust be reviewed as applicable.1.13 Hose Cleanliness:Hose components may vary in cleanliness levels. Caremust be taken to ensure that the assemblies selected havean adequate level of cleanliness for the application.1.14 Welding and Brazing:Heating of plated parts, including hose fittings and adaptors,above 232 C (450 F) such as during welding, brazing, orsoldering may emit deadly gases.1.15 Electrical Conductivity:Certain applications require that a hose be non-conductiveto prevent electrical current flow. Other applications requirethe hose to be sufficiently conductive to drain off staticelectricity.Extreme care must be exercised when selecting hose andfittings for these or any other applications in which electricalconductivity or non-conductivity is a factor.For applications that require hose to be electrically nonconductive, including but not limited to applications nearhigh voltage electric lines, only special non-conductivehose can be used.The manufacturer of the equipment in which the nonconductive hose is to be used must be consulted to becertain that the hose and fittings that are selected areproper for the application.

ALFAGOMMA // HOSE GUIDELINES2. INSTALLATION - After the selection of the correct hose,the following factors must be considered prior to hoseand fitting assembly and installation.2.1 Pre-Installation Inspection:Prior to installation, a careful examination of the hose mustbe performed. All components must be checked for correctstyle, size, and length. The hose must be examined forcleanliness, obstructions, blisters, cover looseness, or anyother visible defects.2.2 Hose and Fitting Assembly:Do not assemble an ALFAGOMMA fitting on anALFAGOMMA hose that is not specified by ALFAGOMMAfor that hose. Do not assemble ALFAGOMMA fittings onanother manufacturer’s hose or an ALFAGOMMA hoseon another manufacturer’s fitting unless ALFAGOMMAapproves the assembly in writing, and the user verifies theassembly and the application through analysis and testing.The ALFAGOMMA published hose assembly instructionsmust be followed for assembling the fittings on the hose.2.3 Related Accessories:Crimp or swage ALFAGOMMA hose or fittings only withALFAGOMMA approved swage or crimp machines andin accordance with the ALFAGOMMA published hoseassembly instructions.2.4 Parts:Do not use any ALFAGOMMA hose fitting part (includingbut not limited to sockets, or inserts) except with the correctALFAGOMMA mating parts, in accordance with ALFAGOMMApublished hose assemby2.5 Reusable/Permanent:Do not reuse any reusable hose coupling that has blown orpulled off a hose. Do not reuse an ALFAGOMMA permanent(that is, crimped or swaged) hose fitting or any part thereof.2.6 Minimum Bend Radius:Installation of a hose at less than the minimum listed bendradius may significantly reduce the hose life. Particularattention must be given to avoid sharp bending at the hose/fitting juncture.2.7 Twist Angle and Orientation:Hose installations must be such that relative motion ofmachine components does not produce twisting.2.8 Securement:In many applications, it may be necessary to restrain,protect, or guide the hose to protect it from damage byunnecessary flexing, pressure surges, and contact withother mechanical components. Care must be taken toensure such restraints do not introduce additional stress orwear points.2.9 Proper Connection of Ports:Proper physical installation of the hose requires a correctlyinstalled port connection while ensuring that no twist ortorque is transferred to the hose.2.10 External Damage:Proper installation is not complete without ensuring thattensile loads, side loads, kinking, flattening, potentialabrasion, thread damage, or damage to sealing surfacesare corrected or eliminated.2.11 System Checkout:After completing the installation all air entrapment must beeliminated and the system pressurised to the maximumsystem pressure and checked for proper function withoutany leaks. Personnel must stay out of potential hazardousareas while testing.3. HOSE AND FITTING MAINTENANCE INSTRUCTIONSEven with proper selection and installation, hose life maybe significantly reduced without a continuing maintenanceprogram. Frequency should be determined by the severityof the application and risk potential. A maintenance programmust be established and followed to include the followingas a minimum:3.1 Visual Inspection Hose/Fitting:Any of the following conditions require immediate shutdown and replacement of the hose assembly: Fitting slippage on hose. Damaged, cut or abraded cover (any reinforcementexposed). Hard, stiff, heat cracked, or charred hose. Cracked, damaged, or badly corroded fittings. Leaks at fitting or in hose. Kinked, crushed, flattened or twisted hose. Blistered, soft, degraded, or loose cover.3.2 Visual Inspection All Other:The following items must be tightened, repaired or replacedas required: Leaking port conditions Remove excess dirt build-up Clamp, guards, shields System fluid level, fluid type and any air entrapment3.3. Functional Test:Operate the system at maximum operating pressure andcheck for possible malfunctions and freedom from leaks.Personnel must stay out of potential hazardous areas whiletesting.3.4 Replacement Intervals:Specific replacement intervals must be consideredbased on previous service life, government or industryrecommendations, or when failures could result inunacceptable downtime, damage, or injury risk.13ALFAGOMMADo not use any ALFAGOMMA hose or fitting for anyapplication requiring non-conductive hose, including but notlimited to applications near high voltage electric lines, unlessthe application is expressly approved in the ALFAGOMMAtechnical publication for the product, the SAFETY GUIDE hoseis both orange in colour and marked “non-conductive”, andthe manufacturer of the equipment on which the hose is to beused specifically approves the particular ALFAGOMMA hoseand fitting for such use.ALFAGOMMA does not supply any hose or fittings forconveying paint in airless paint spraying or similar applicationsand therefore should not be used. A special hose and fittingassembly is required for this application, to avoid staticelectricity buildup which could cause a spark that may resultsin an explosion and/or fire.The electrical conductivity or non-conductivity of hoseand fittings is dependant upon many factors and may besusceptible to change. These factors include but are not limitedto the various materials used to make the hose and the fittings,manufacturing methods (including moisture control), how thefittings contact the hose, age and amount of deterioration ordamage or other changes, moisture content of the hose at andparticular time, and others factors.

ALFAGOMMA // HOSE GUIDELINESCORRECT ASSEMBLY INSTALLATIONALFAGOMMA14Satisfactory performance and appearance depend uponproper hose installation. Excessive length destroys the trimappearance of an installation and adds unnecessarily tothe cost of the equipment. Hose assemblies of insufficientlength to permit adequate flexing, expansion or contractionwill cause poor power transmission and shorten the life ofthe hose.The diagrams below offer suggestions for proper hoseinstallations to obtain the maximum in performance andeconomy.RIGHTWRONGAdequate hose length is most important to distributemovement on flexing applications and to avoid abrasion.WRONGWRONGRIGHTRIGHTSince hose may change in length from 2% to -4% underthe surge of high pressure, provide sufficient slack forexpansion and contraction.To avoid twisting in hose lines bent in two planes, clamphose at change of plane, as shown.RIGHTWRONGAvoid sharp twist or bend in hose by using proper angleadapters.RIGHTNever use abending radiusless than theminimumamount shownin the table.WRONGWRONGRIGHTRIGHTWhere the radius falls below the required minimum, anangle adapter should be used as shown above to avoidsharp bends in hose.To prevent twisting and distortion, hose should be bent inthe same plane as the motion of the boss to which the hoseis connected.WRONGWRONGRIGHTObtain direct routing of hose through use of 45 and 90 adapters and fittings. Improve appearance by avoidingexcessive hose length.High PressureNo PressureDue to changes in length when hose is pressurised, donot clamp at bends so curves absorb changes and protectthe hose with a spring guard. Do not clamp high and lowpressure lines together and protect the hose with a springguard.www.alfagomma.comHose should not be twisted. Hose is weakened wheninstalled in twisted position. Also pressure in twisted hosetends to loosen fitting connections. Design so that machinemotion produces bending rather than twisting.RIGHTWRONGHigh PressureRIGHTWRONGRIGHTNever use a bending radius less than the minimum shownin the hose specification tables. Avoid sharp bend in hoseto reduce collapsing of line and restriction of flow by usingproper spring guard. Exceeding minimum bend radius willgreatly reduce hose assembly life.

ALFAGOMMA // HOSE GUIDELINESHOW TO DETERMINE CORRECT ASSEMBLY LENGTHFor most assemblies, the correct assembly length maybe determined by direct measurement of the equipmentor a drawing. Minimum bend radii as shown in the hosespecification tables should be observed.Assemblies are measured to the end of the seal.To determine the length of hose needed in makingassemblies with permanent or reusable couplings, subtractDimension “C” (Cut off factor) for each coupling from therequired overall assembly length. Dimension “C” may befound in the coupling specification tables.HOW TO MEASURE ASSEMBLIESLength over nipplesLength between S.P. and nipple endsSwivel

reflected in the Group's state-of-the-art product portfolio, which also include adapters and swivel connectors. MANUFACTURING PLANTS 16 IN 8 COUNTRIES ITALY - FINLAND GERMANY - UK USA - BRAZIL CHINA - MALAYSIA 79 IN 21 COUNTRIES AND 5 CONTINENTS SUBSIDIARIES AND ASSEMBLY PLANTS QUALITY CERTIFICATION ISO ISO 9001 SINCE 1993 ISO 14001 .