Hydraulic Hose Selection and Manufacturing Process
Hydraulic Hose Selection and Manufacturing Process
Hydraulic Hose Selection and Manufacturing Process
The hydraulic fittings we depend on every day can be found in everything from heavy machinery to shipping vessels to manufacturing equipment. All that heavy duty gear, we need hydraulic hoses to safely transport fluids delivered under pressure to do the job.
Many of these hydraulic systems also work in tight spaces and require the use of flexible hoses with permanent connections. This permanent connection, or hydraulic connection, comes from curved metal collars at the end of the hose. It is important that this is done correctly.
The best place to start any hydraulic system project is with advice from an experienced professional. Careful planning of your design will help you build a more reliable system in less time. That's right, some insights will make your project more perfect.
Now that you have the correct hoses and connections, this
Let's look at how to clamp fittings and maintain reliable and permanent connections.
A quick guide to pressing hydraulic connections
Get a hose pressing machine. Once you have identified the correct tool, open the jaws and insert the hose socket into the fitting. Turn the adjustment knob on the pliers until the jaws are wide enough for the fitting to fit into the jaws.
Place the hydraulic hose next to the fitting. Then, insert the end of the hose even with the end of the metal socket in the fitting. Make a mark on the hose at the socket end of the fitting.
Twist the hose into place and attach it to the fitting. Continue pushing the hose until it reaches the line you made at the end of the collar.
THINGS TO BE CONSIDERED WHEN CONNECTING HYDRAULIC PIPE AND HYDRAULIC HOSE:
Different pipe and hose diameters should not be used in hydraulic systems, and sudden cross-sectional narrowing or cross-sectional increases should be avoided.
Sharp corners should be avoided in turns in lines used in hydraulic systems.
Excessively long and unnecessary pipe and hose lines should be avoided.
To prevent vibration and cavitation in the system, pipes should be fixed with clamps at regular intervals.
The suction pipe or hose must be short.
The return pipe or hose must be short.
Hoses should be used in moving and vibrating areas.
Thermal expansion should be taken into account in pipe connections.
Pipe diameters or hydraulic hose diameters must be sufficient to provide the desired flow rate and pressure.
Pipe wall thickness and hose type must be selected to meet the working pressure and temperature values.
Pipe and hydraulic hose connections must be leak-proof.
The inner surfaces of the pipe or hydraulic hose must be smooth.
The innermost layer of the Hydraulic Hose must be resistant to the fluid used in the system.
SELECTING THE CORRECT PIPE OR HYDRAULIC HOSE DIAMETER
The pump suction line must be larger than the pipe or hydraulic hose in the discharge line.
The pipeline from the tank to the pump should be kept as short as possible.
Elbows or similar elements should be avoided at the entrances to the pump. Otherwise, overheating will occur in the pump, which may damage the pump and other elements.
When calculating the suction line, the Flow Rate value between V suction = 0.8-1 m/sec is taken.
The pump pressure line should be chosen with a smaller diameter than the suction and return lines. Otherwise, we cannot get the desired pressure from the pump. When calculating the discharge line, the flow rate value between V discharge = 5-6 m/sec is taken.
The pump return line, like the suction line, should be chosen larger than the pressure line. Otherwise, limited passages in the return lines will cause the pressure to rise and power to be wasted unnecessarily. When calculating the return line
V rotation=2-4 m/sec Flow rate value is taken.
d= Pipe Inner Diameter or hydraulic hose inner diameter (mm)
Q= Pump Flow (Lt/Min)
V= Flow Velocity (m/sec)
V (For Suction Line)= 0.8 – 1 m/sec
V (For Pressure Line)= 5 – 6 m/sec
V (For Return Line)= 2 – 4 m/sec
HYDRAULIC HOSE SELECTION
First of all, it is necessary to determine the electrical conductivity of the environment in which the hydraulic hose will be used. In some applications, hydraulic hoses are required not to conduct electricity, and in other applications, it is required that they conduct static electricity generated on the hose. Since this choice directly affects human life, it should never be forgotten and its determination should be made in a way that leaves no question marks.
When determining the Hydraulic Hose, it must be determined whether the maximum working pressure of the system is compatible with the working pressure of the selected hose. It should not be forgotten that this criterion directly affects human life.
Since the structure of suction line hoses and pressure line hoses is different, as stated in the product introduction, it is important to determine whether the selected hydraulic hose will be used in the pressure line or the suction line. It should not be forgotten that the wrong choice to be made here will cause serious malfunctions in the system elements.
It must be determined that the operating temperature of the selected hydraulic hose is suitable for the fluid temperature to be used and the ambient temperature. A mistake made here may cause a fire in the facility or cost human life. If necessary, heat protectors such as glass fiber should be placed on the hose.
If the selected Hydraulic Hoses are used in gas systems, the outer surfaces of the hoses must be perforated, because gas passes through the layers more easily than liquid. Therefore, balloons form on the hose, and if the gas used is explosive, human life is endangered due to the risk of explosion.
The diameter of the selected Hydraulic Hose must be determined very well, otherwise the equipment used in the system will be damaged due to excess or insufficient flow or will operate with low efficiency.
The route of the hose must be determined very well in order not to cause complexity in the system.
In order for the Hydraulic Hose with Fittings to be healthy, the Fittings and Hoses must be compatible with each other.
Mechanical loads in the system directly affect the life of the hose. Therefore, when choosing a hose, consideration should be given to other criteria as well.
The hose must always be protected against shear effects and friction effects.
Hose length should be determined carefully. Long hose causes friction, twists and complications. Short hose shortens the life of the hose.
PRESSING OF HYDRAULIC HOSE FITTINGS
Before pressing, the dimensions of all selected materials (Hoses, Sockets and Unions) should be checked.
Hoses and nozzles that are not compatible with each other should never be used together.
The mold size and settings of the machine where pressing will be done should be checked.
Old materials should never be reused. (Removing the fittings and pressing them again or pressing a new fitting onto the old hose)
Since the hose pressing process directly affects human life in many cases, people who do the pressing process should think about what kind of problems may arise from the smallest mistake and should pay due attention to the pressing process.
Mistakes that can be made during the Hydraulic Hose Pressing process are as follows:
Shipping Hydraulic Hose with Fittings Without Pressing the Fittings onto the Hose
Incorrect calculation of the pressing size or misreading from the table and performing the pressing
Pressing process to the right size but with the wrong mold
Performing the pressing process without sufficiently inserting the couplings into the hose.
Deterioration that may occur due to the couplings hitting the jaws of the press when pressing elbow or bent special couplings.
Part of the socket remaining outside the mold during the pressing process.
Angles of double elbow pre-nipple in hydraulic hose lines
According to DIN 20066 Pkt.4
If no information is given about the angles, the pre-nipples are pressed in the direction of the natural bend of the hose.
Angles are only reported if the elbows are to be pressed in different directions.
By turning it counterclockwise, the fixture facing you will face down.
If no angle is specified, the hose is pressed in the direction of its natural bend. V= 0°
The first reported cantilever fixture is pressed in the natural bending direction (front/down). Next reported luminaire counterclockwise
(i.e. V = 90°) is pressed.
First specified fitting in the natural twist direction of the hose (front/downward) Next stated counterclockwise
(V= 270°)
THINGS TO BE CONSIDERED WHEN INSTALLING HYDRAULIC HOSES WITH FITTINGS
Storage & Traceability – HOSE
Listed below are the standards that specify the storage conditions of hoses:
Features of these standards:
ISO 8331: “Rubber and plastic hoses and hose fittings – Guide for storage use and enclosure selection”
DIN20066: “Hydraulic Fluid Power; Hose Fittings; Service Performance Evaluation”
Storage conditions have been noted to potentially reduce the service life of hose fittings. Stresses are transferred which can potentially reduce the service life of the fitting hose. It also includes a storage period of 6 years, which is the maximum usage capacity. As a result, each storage period consumes the service life of the union hose in equal parts.
BS 5244:”Storage and application of expiry dates for hose fittings and hydraulic rubber hoses”
Maximum Storage Time for Hoses and Fittings
3 years: no testing required on the hose
3-5 years: hydraulic pressure trial tests are required.
5-8 years: hydraulic pressure trial tests, impact, knocking, cracking, cold elasticity electrical tests are required.
8 years: scrapped.
Maximum Storage Period of Fittings Placed on Stored Material
3 years: no testing required on fittings
3-5 years: hydraulic pressure trial tests, impact tests are required.
8 years; scrapped.
The fitting hose service period varies depending on the material it connects. Therefore, it is not possible to make a general estimate regarding this period. Accordingly, it is recommended that records be kept with a view to each material and its specific application.
SAE J1273:” Recommended Practices for Hydraulic Hose Installation”
Maximum Storage Time
Rubber hoses:
<10 years in the party
After <10 years, the fittings are subjected to visual inspection and trial tests.
Thermoplastic or PTFE hoses are considered unlimited.
This standard covers the requirements on general elements for hoses in storage.
explains its impact.
This standard hose fitting service life hints at unforeseen effects
Each system must be carefully analyzed for order.
The user must be informed about the maintenance schedule for these standard hose fittings.
It gives general criteria that can be applied.
This service program should be performed on all applications and hoses.
Application to establish standard, visual inspection frequency and functional tests
It requires consideration of factors such as its nature and difficulty, past history, etc.
General storage conditions and placement policies are provided in all standards. Suggestions are presented by associating and listing the following parameters.
HEAT DEGREE
Usually 0-35 degrees (Preferably 15 degrees)
MOISTURE
Very humid or dry conditions should be avoided. The recommended average humidity should not be higher than around 65%.
LIGHT
Hoses should be protected from sunlight or strong artificial light. It is generally recommended that the windows of the warehouse be painted red or orange, and the hoses should be stored in closed boxes.
OXYGEN AND OZONE
Due to the harmful effects of ozone on rubber production, hoses should be stored in closed, ventilated boxes, and proximity to mercury vapor lamps or tubes and high voltage electronic materials should be avoided.
OILS, SOLVENTS, GREASE OILS
Stored hoses must be protected from possible contact with risky objects.
HEAT SOURCES
Hoses should be stored away from latent (indirect) heat sources.
ELECTRIC AND MAGNETIC FIELD
The proximity of materials in storage areas should be avoided as they may create electrical and magnetic fields.
Storage areas should not be close to materials that may cause current and heating in magnetic parts or create electric and magnetic fields.
STORAGE CONDITIONS
Hoses should always be stored in comfortable situations, without damaging or forcing them.
The recommended minimum curling circumference should be as wide as possible.
The hose should be stored in a way to avoid corrosion of its outer covering caused by accidental contact with the environment.
MANUAL PROCESSING METHODS
When touching the hoses, they should be protected against impacts and abrasion of the hose coating as much as possible.
VISUAL HOSE IDENTIFICATION
Hydraulic Hose Production Line and Production Process Map with Images;
Hydraulic Hose Cutting Operation;
Hydraulic Hose Stripping Operation;
Hydraulic Hose Fitting Assembly Operation;
Hydraulic Hose Pressing Operation;
Hydraulic Hose Washing Operation;
Hydraulic Hose Test Operation;
Hydraulic Hose Marking and Packaging Operation with Shiring;