Hydraulic cylinder seals are an integral part of any hydraulic system because they control and maintain the pressure and movement of hydraulic fluid. Without them, hydraulic systems can't work correctly.
The correct hydraulic cylinder seals, will maintain the integrity of the machine's system and extend its working life. Our hydraulic cylinder resealing services ensure such equipment runs at peak performance.
In this blog, we look at how hydraulic cylinder seals are designed to prevent leakage, the main types of seals, and the materials they are made of to withstand high pressure.
Hydraulic cylinder seals form a barrier between different components in a hydraulic cylinder. They are made with specific materials that adjust to varying clearance gap sizes and must be strong enough to withstand the shear stress created by system pressure.
When selecting hydraulics cylinders seals, it is essential to consider the type of surfaces they will be used on. A static seal should be employed if there is no relative motion between mating surfaces. On the other hand, if there is motion between surfaces (either reciprocating or oscillating), then a dynamic seal should be used.
A hydraulic cylinder seal protects the hydraulic fluid and prevents the hydraulic system's components from mixing with external fluids. They also help to improve a system's overall efficiency and reliability, among other things:
Different types of sealing are available for hydraulic cylinders, ranging from simple O-rings to complex rotary seals, hydraulic ram seals, and hydraulic oil seals. Depending on the application, the type of seal required will vary; but all seals serve the same purpose of creating a secure, fluid-tight seal.
Piston seals, also known as piston rings, are mechanical seals that reduce leakage between components in a reciprocating motion. Therefore, the primary function of a hydraulic piston seal is to form a seal between the cylinder tube and piston, preventing the leakage of lubricants and gases.
They also help maintain the pressure within the cylinder, allowing the piston to move efficiently. Piston seals are used in various applications, such as air compressors, hydraulic pumps, and internal combustion engines. As critical components in any reciprocating system, they ensure the efficient movement of the parts while keeping the system sealed and maintaining the pressure within.
Wiper seals keep dirt, debris, and other contaminants from entering a system or machine. They are typically used for applications such as hydraulic cylinders, pumps, and valves and can be made from various materials, including rubber, polyurethane, and thermoplastic elastomers.
Designed with a lip that scrapes the system's surface when it moves, they eliminate any particles that may have accumulated. Additionally, wiper seals provide an extra barrier against entering liquids and gases. They are commonly used in conjunction with other seals such as O-rings, and rod seals to provide a comprehensive sealing solution.
Hydraulic rod seals consist of a metal rod inserted in a rubber or plastic sealing element. The sealing part conforms to the rod surface, creating a tight seal that prevents internal pressure from escaping and external contaminants from entering the cylinder.
In addition, the buffer seal cushions the rod from shock and vibration, increasing the life of the cylinder and its components. Rod and buffer seals are suitable for mobile and industrial applications, such as agricultural and construction equipment, where they are exposed to dirt, dust, and moisture.
The difference between a rod seal vs. piston seal: Rod seals are flexible and keep pressure in and contaminants out, while piston seals are rigid seals that keep pressure in and lubricate in.
Guide rings are mounted on pistons and piston rods of hydraulic cylinders to absorb side loads and prevent metal-to-metal contact between sliding parts, such as rod and gland/piston and bore. They are typically placed inward of both the rod and buffer seal and should be lubricated on assembly with the same lubricant used in the hydraulic system.
These rings are available in metallic and nonmetallic options. Factors such as the diameter of the rod and piston, the stroke length, pressure, type of seal, and lubrication must be considered when selecting guide rings.
Choosing suitable seal material is crucial, as it determines the overall quality and durability of hydraulic seals. Your manufacturer can suggest appropriate materials - whether you need hydraulic seal rings, o-rings, or any other type of seal - to meet specific application needs. Below are the most common materials used to create seals:
With a wide variety of hydraulic seals available, it is essential to select wisely to ensure cost-effective hydraulic cylinder repairs. Doing so will help to guarantee a long operating life and improved performance over the lifetime of the hydraulic cylinder. Incorrectly sealing equipment can lead to premature wear and eventual failure.
As a hydraulic cylinder repair company, our team has been resealing hydraulic cylinders for over 30 years. We can help you no matter what your hydraulic system needs, and we are always happy to offer seal recommendations and answer any questions.
Having done thousands of repairs, we have extensive knowledge and experience to expertly service your repairs and perform preventative maintenance. We also have a large inventory of seals and stock common steel shapes if your repair requires fabrication. If you&#;re looking for experienced and professional hydraulic repair service, contact Cylinders, Inc. today!
FPE Seals
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Jul 13,
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Hydraulic seals are used in industrial applications, that prevent a fluid or gas from passing between different components of a cylinder, ensuring that the system operates efficiently and safely. However, not all seals are created equal, and different applications may require different types of seals. In this blog, we discuss the factors to consider when choosing the right seal, that is created in the appropriate material, to best suit your application.
When selecting a hydraulic seal, it&#;s important to consider its material and design, to ensure that it works effectively, safely and reliably.
You will get efficient and thoughtful service from CDI.
Temperature is one of the most important factors to consider when selecting seals. The temperature range of the seal must be compatible with the operating environment. If the seal is exposed to temperatures outside of its range, it can fail prematurely.
The temperature range of a seal is determined by the material it is made from. Different materials have different thermal properties. Some materials, such as rubber, are good at sealing at low temperatures, while other materials, such as metal, are better at sealing at high temperatures.
In addition to the operating temperature, the seal must also be able to withstand the temperature fluctuations that may occur in the environment. For example, a seal that is installed in a climate-controlled environment may not be able to withstand the extreme temperatures that can occur outdoors.
Not all seals can withstand high pressure. Therefore, if you are looking to seal a high-pressure application, it is vital to select a seal in a material that can cope without deforming or breaking. The seal design must be able to create a tight seal without creating too much friction and the seal must be lubricated properly to prevent wear and tear.
Some of the most common types of seals used in high-pressure applications include:
O-rings: O-rings are made of a flexible material that can conform to the surface of the seal housing. They are available in a variety of materials, including rubber, nitrile, and fluorocarbon.
V-rings: V-rings are made of a stiffer material than O-rings and can withstand higher pressures. They are also available in a variety of materials, including rubber, nitrile, and fluorocarbon.
Piston seals: Piston seals are used to seal pistons in cylinders. They are made of a variety of materials, including rubber, nitrile, and fluorocarbon.
If the seal is not compatible with the fluid used in a hydraulic system, it can degrade the seal material prematurely, causing the seal to leak. When evaluating fluid compatibility numerous factors need to be considered including the chemical composition of the fluid, the operating temperature and pressure, and the seal material. Compatibility will vary dependant on the material type. For example, elastomers are generally compatible with a wide range of fluids, while plastics and metals are more limited in their compatibility.
Properties: Nitrile seals have a good resistance to elongation at break, abrasion and compression set, but their flexibility suffers somewhat in the lower temperature range. Seals made from this material have a low resistance to ozone and must be stored carefully in most environments.
Temperature: Nitrile can withstand temperature range from -30°C to +100°C
Fluid Compatibility: The most common nitrile copolymer blend is the compound known as Buna-N. Possessing very good resistance to petroleum based hydraulic oils, Buna-N also works well with fuels such as diesel or gasoline.
Properties: PTFE has chemical inertness, high heat resistance, low temperature flexibility, low running friction, and non-adhesive characteristics. Because of a lack of resilience (memory) in PTFE, an energizer is most often employed to obtain the desired fit. Most PTFE seals, to retain their toughness and flexibility, are fortified with short glass fibres, bronze flashes, carbon graphite, or a combination of these fillers.
Temperature: PTFE can withstand temperatures to over 300°C but are often reduced by the filler or energizer employed.
Fluid Compatibility: PTFE seals are compatible with most chemicals, including acids, bases, and solvents.
Properties: Ethylene-Propylene (EPDM) has good heat resistance, low compression set and good flexibility at low temperatures.
Temperature: Ethylene-Propylene temperature ranges between -45°C and +150°C .
Fluid Compatibility: Ethylene-Propylene can be used for sealing phosphate ester hydraulic fluids such as Skydrol but is not suitable for petroleum based fluid. Ethylene-Propylene is highly effective for use with steam, acetone, and dilute acids and bases. Specially compounded Ethylene-Propylene can be made suitable for automobile brake systems.
Properties: Polyurethane is highly resistant to oil swell, ozone, oxidation, abrasion and has excellent cut resistance. Highly resilient, urethanes also have high tensile strength and elongation properties. Formulated of copolymers of ether or ester based urethanes, this material is used in a wide application of seals, wipers, backup rings, cushions, bumpers, and a myriad of other uses.
Temperature: Most urethane seals remain flexible and efficient in temperatures ranging between -54°C and +93°C with some able to withstand intermittent temperatures up to +135°C.
Fluid Compatibility: Polyurethane is compatible with hydraulic systems using petroleum based fluids.
Properties: Silicone is an elastomer made from silicon, oxygen, hydrogen, and carbon. It has a high resistance to dry heat, ultraviolet light, and ozone. This material is not recommended for dynamic situations due to poor abrasion resistance and high friction characteristics.
Temperature: Silicone temperature ranges from -54°C to +204°C
Properties: Viton® &#; FPM / Viton® equivalent FKM combines high temperature resistance with excellent chemical resistance. This material is not recommended for use in low temperatures or in aircraft hydraulic fluids.
Temperature: Viton® &#; FPM / Viton® equivalent FKM temperature ranges is -20° to +400° F.
Fluid Compatibility: Excellent for use with alcohol and aromatic fuels and highly resistant to ultraviolet light and ozone.
Properties: PEEK has excellent strength, fatigue resistance and stability in high temperature environments, with a melting point around 343°C, and very good chemical resistance.
Temperature: PolyEther Ether Ketone (PEEK) recommended operating temperature is -54°C up to +260°C
Fluid Compatibility: PEEK is compatible with almost any of the solvents used in HPLC.
Properties: Hydrogenated Nitrile is also known as saturated Nitrile have excellent resistance to many modern fuels, resistance to high energy radiation & good abrasion resistance.
Temperature: Hydrogenated Nitrile Butadiene Rubber (HNBR) temperature ranges from -40°C to +150°C
Fluid Compatibility: HNBR is widely used in automotive and oil industries and maintains excellent resistance to motor oils, sour gas, amine/oil mixtures, oxidized fuels, and lubricating oils. HNBR is resistant to mineral oil-based hydraulic fluids, animal and vegetable fats, diesel fuel, ozone, sour gas, dilute acids, and bases.
Properties: UHMWPE (Ultra High Molecular Weight Polyethylene) has very long molecular chains that helps to transfer load more effectively, strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made. It has very high abrasion resistance, shows zero water absorption, is self-lubricating and has a friction coefficient only slightly above most filled PTFE.
Temperature: Ultra high molecular-weight polyethylene (UHMWPE) recommended operating range is -200°C up to just +80°C
Fluid Compatibility: UHMWPE is stable in all hydraulic fluids, with high resistance to acids, bases, and aggressive media.
Selecting the right seal material is crucial to ensure the efficient and safe operation of machines, devices, and systems. Not sure what you are need? Get in touch with our knowledgeable team here at FPE Seals, who will discuss your requirements based on your application, and help you find the right seal for the job.
Original source at FPE Seals
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