What are hydraulic fittings?
Hydraulic fittings are available in a wide variety of types and applications. They are used to connect hydraulic hoses to components such as hydraulic cylinders, pipes or various types of hydraulic hoses in hydraulic systems. Different types of hydraulic connections cause fluid to flow, change direction, deflect, or mix. These connections must be able to create a tight seal and prevent leaks in the application. These fittings are widely used in hydraulic applications such as plumbing, robotics, assembly lines and heavy equipment. Hydraulic fittings are used to seal hydraulic oil or liquid inside the system. Therefore, the joints must be compatible with the fluids used. The hydraulic fluid provides the energy needed for the system to do its job. There are several types of hydraulic fluids on the market.
Figure 1: Hydraulic connections
Common types of hydraulic connections
Petroleum-based liquids: Petroleum or mineral liquid is the most widely used hydraulic fluid. Additives in these liquids protect against rust and oxidation, wear, rot, and extreme pressure. These liquids are generally of high quality, low cost and widely available.
Water-based liquids: These liquids have a high water content, therefore, they are used for fire resistance. They are available as water-in-oil emulsions, oil-in-water emulsions, and water-glycol mixtures. They are more expensive than petroleum-based liquids and have lower abrasion resistance.
Synthetic Liquids: These are man-made liquids that provide benefits such as fire resistance, low friction, and thermal stability. Due to their excellent lubricating properties, they are ideal for use in high temperature and high pressure applications. However, they are more expensive than oil-based liquids and may be slightly toxic.
Types of hydraulic connections:
The following types of hydraulic fittings are widely used in the European and US markets:
ORFS: ORFS (O-Ring Face Seal) joints have an O-ring groove on the smooth surface of the joints. Sealing of such connections is achieved by connecting the O-ring with the smooth face of the female connector. These connections are ideal for high pressure applications and provide a leak-free connection. ORFS connections can be of the following types:
Direct ORFS connections: Direct screw connections with male ORFS connections to G, NPT or male metric strings
Elbow ORFS connections: Elbow screw connection with one ORFS female connector and the other female ORFS connector at an angle
Tee ORFS connections: T-shaped screw connection with one female ORFS connection port and two male ORFS connection ports
Crossover ORFS connections: Four male ORFS connection ports in cross-orientation, useful for distributing or combining media
These ORFS connections are usually fitted with accessories such as plugs, end caps, and O-rings.
DIN / BSP fittings: DIN (Deutsches Institut für Normung) and BSP (British Standard Pipe) fittings are commonly used in Europe for hydraulic fittings. DIN fittings guarantee interchangeability with different brands of fittings and are used in industrial, construction and oil and bag industries. BSP fittings comply with the BSP standard for screw threads. They are used for sealing and connecting pipes and they can be obtained by connecting the outer thread (male) with the inner thread (female). They are mostly used in the plumbing industry and are very popular, except in North America, where NPT standards are used.
Selection criteria and points of interest of hydraulic connections:
The following criteria must be considered before choosing the right type of hydraulic fittings for your application:
1- Size: The inner and outer diameters of the joints are two important sizes that must be considered. These connection diameters must be compatible with the hose diameter. Excessive or excessive connections may cause leakage or disconnection.
2- Material: Hydraulic fittings must be compatible with hydraulic fluid and the working environment. The most common fittings are brass, aluminum, steel or stainless steel. O NBR (Nitrile) rings are the most widely used sealing material.
3- Temperature: Hydraulic connections should be proportional to your temperature range.
4- Pressure: Hydraulic connections should be proportional to your pressure range, including pressure increase. Performance above this range can damage connections.
5. Application: The type of application also determines the type of connections used. T or cross joints are used for mixing or distribution applications.
6- Assembly: If the hydraulic system requires frequent connection and disconnection of hose or pipe, fast hydraulic connection connections can be used. Likewise, hydraulic compression joints can be used to meet the need for welding or soldering joints. It uses a compression nut to tighten against the ferrule, creating a very strong seal. This material can be used in areas with high temperatures because welded joints can leak in such environments.
How to properly connect to the hydraulic hose:
For proper connection of hydraulic hose with hydraulic fittings:
1) Make sure it matches the length of the hose. To reduce the risk of contamination and damage to the assembly, a hose cutter can be used to cut it to the desired size with a clean end.
2) Select the appropriate hydraulic hose fittings. Make sure the size, pressure, temperature, material, style and direction of the connections match your performance.
3) Determine the depth of connection of the connections and mark with a marker on the hose. Lubricate the hose (if necessary) and insert the hose into the fittings until it rests on the hose.
4) Adjust the coil to the appropriate diameter, place the end of the hose in the crimping device and remove the hose.
5) Confirm the diameter of the wrinkles.
6) Clean the hose assembly so that it is not contaminated with the hose brush.
Common applications of hydraulic connections:
Hydraulic fittings are used in piping and pipes with hydraulic hoses in the following cases:
1) Factory applications such as assembly lines, presses, robotics, hydraulic power units
2) Construction and mining equipment
3) Agricultural equipment
4) Plumbing programs
5) Oil and gas industry
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