Hydraulic Cylinder Seals: Types, Materials, Functions

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.

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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.

What Are Hydraulic Cylinder Seals?

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.

Main Functions of Hydraulic Cylinder Seals

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:

• &#;Pressure adaptability and contamination prevention: Hydraulic seals are designed to function with both low-pressure and high-pressure. Furthermore, they prevent contamination by acting as a barrier to keep dirt out. &#;
• Controlling leaks and preventing blowouts: Hydraulic cylinder seals are designed to create a pressure-tight seal around the piston rod, reducing friction and preventing leaks and blowouts. They are made from unique materials that resist wear from hydraulic fluid and feature a lip to create a positive seal around the piston rod.&#;
• Cost-effectiveness and easy maintenance: Hydraulic cylinder seals are designed to reduce the cost of parts and labor, be resistant to wear and tear, and require minimal maintenance. They are easy to install and replace and provide a high level of performance, making them a cost-effective and low-maintenance solution for hydraulic systems.&#;
• High durability and adaptability: Manufacturers around the globe make high-quality hydraulic cylinder seal kits that provide durability and a long lifespan. Constructed from top-notch materials, these advanced seals are engineered to withstand harsh conditions and keep the machinery running smoothly.&#;
• Safe and water resistance: Renowned for resisting water, chemicals, and wear and tear, hydraulic seals are a popular choice for mining businesses that want to speed up mineral extraction. They are also safe to use in various industries, such as those producing pharmaceuticals and chemicals.

Main Types of Hydraulic Seals

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

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

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.

Rod & Buffer Seals

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 & Lubrication

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.

What Materials Are Used in Hydraulic Seals?

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:

• &#;Rubber: A hydraulic rubber seal is suitable for applications requiring high flexibility and compressibility. Nitrile butadiene rubber (NBR), fluoroelastomer (FKM), and hydrogenated nitrile butadiene rubber (HNBR) are popular materials used to create these seals due to their resistance to grease, mineral oils, and other hydraulic fluids.&#;
• Polytetrafluoroethylene: PTFE has remarkable durability when exposed to extreme temperatures, pressures, and caustic chemicals. Its low coefficient of friction means it requires less lubrication than other seals, and it can perform effectively even when used dry.&#;
• Rigid plastics: Plastic hydraulic cylinder seals offer resistance to temperature, pressure, and chemical reactivity and come in various materials. The strength of seals can be improved by utilizing engineered plastics instead of commodity plastics. Plastic seals are much more rigid than rubber or PTFE seals, providing additional power to the cylinder.&#;
• Thermoplastic Elastomers: TPEs offer excellent strength and flexibility, making them ideal for hydraulic cylinder seals. They are highly resistant to abrasion and tearing and can keep constant pressure for extended periods. Their combination of plastic and rubber properties makes them an excellent choice for components that require durability and elasticity.

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.

Conclusion

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!

Hydraulic systems play a critical role in various industries, powering machinery and equipment with precision and efficiency. These systems are integral to operations in industries such as Oil & Gas, Cranes & Aerial Lifts, Construction, Forestry, Agriculture and Mining, where they enable the movement of heavy loads, the operation of machinery, and the execution of complex mechanical tasks. At the heart of these systems lie hydraulic cylinders, converting fluid power into mechanical force allowing for controlled and powerful movements which are essential to the functionality of equipment in diverse industrial applications. An integral element to these systems is the Hydraulic Cylinder Seals.

A key component to ensuring the optimal performance of these cylinders is a hydraulic seal. This small but mighty piece of the cylinder is essential for maintaining the integrity and efficiency of the entire system. They prevent leaks by containing the hydraulic fluid within the system, ensuring the pressure needed for operation is maintained. They also keep contaminants out of the cylinder, which is important for protecting its internal components from damage and wear. The reliability and longevity of hydraulic systems are heavily dependent on the quality and performance of seals.

At RHK Hydraulic Cylinder Services Inc., we pride ourselves on being industry leaders in complete hydraulic cylinder manufacturing, service and repair. With more than three decades of experience, we provide top-notch solutions tailored to meet each project&#;s specific needs. Our expertise in custom cylinder design and our deep understanding of hydraulic systems enable us to deliver products and services that ensure top performance and longevity of your equipment. We&#;re dedicated to ensuring that every hydraulic cylinder we service and manufacture meets the highest standards of quality and reliability.

Various Materials Used for Seals

The operating environment significantly influences the choice of seal material. For instance, in applications exposed to abrasive particles or harsh chemicals, seals made from durable and chemically resistant materials such as PTFE or polyurethane are preferable. Polyurethane seals are ideal for environments with high abrasion, such as mining and construction, due to their excellent wear resistance. PTFE seals offer superior chemical resistance, making them suitable for applications involving aggressive chemicals or solvents. In contrast, nitrile rubber seals are suitable for environments with moderate temperatures and exposure to hydraulic fluids.

Hydraulic cylinders operate under varying pressure and temperature conditions, affecting seal performance. High-pressure applications require seals with excellent strength and abrasion resistance, such as polyurethane. For high-temperature environments, PTFE seals are ideal due to their stability and low friction properties. Polyurethane seals can withstand high pressures and provide excellent wear resistance, making them suitable for heavy-duty applications. PTFE seals maintain their properties at high temperatures, making them ideal for applications in extreme heat, such as in foundries or steel mills.

Contact us to discuss your requirements of hydraulic oil seal manufacturers. Our experienced sales team can help you identify the options that best suit your needs.

The hydraulic fluid used in the system also determines the suitable seal material. Nitrile rubber seals are compatible with most hydraulic fluids, making them a versatile choice. However, for systems using specialized fluids or operating in extreme conditions, PTFE or polyurethane seals offer enhanced performance and longevity. Nitrile rubber seals are compatible with a wide range of standard hydraulic fluids, making them suitable for general-purpose applications. On the other hand, PTFE seals offer excellent chemical resistance and are suitable for systems using specialized synthetic or bio-based hydraulic fluids.

Piston Seals vs. Rod Seals: Exploring Their Unique Roles

Hydraulic cylinders rely on several types of seals, each serving a specific purpose. Among the most common are piston seals and rod seals.

Piston seals, also known as piston rings, are located in the cylinder barrel, creating a seal between the piston and the cylinder bore. Their primary function is to contain the pressurized hydraulic fluid on one side of the piston, allowing the cylinder to generate force in a specific direction. Piston seals must withstand high pressure and dynamic movement, making the material they&#;re made critical to the overall functionality of the hydraulic cylinder.

There are two common types of piston seals used in hydraulic cylinders:

Single-Acting Seals: When it comes to single-acting seals, they are designed for cylinders that apply force in one direction. They&#;re typically used in applications where the piston only moves in one direction and returns to its original position via external force or spring.

Double-acting seals: These seals are used in cylinders that apply force in both directions. They must withstand pressure from both sides of the piston, requiring materials with strong wear resistance and durability.

Rod seals, located in the gland or seal housing, prevent hydraulic fluid from leaking out of the cylinder and protect the internal components from contamination. These seals must perform under dynamic conditions, withstanding the reciprocating motion of the rod. The effectiveness of rod seals directly impacts the cylinder&#;s efficiency and the overall hydraulic system&#;s performance. There are also two types of rod seals:

Lip seals: They feature a flexible lip that creates a seal against the rod, preventing fluid leakage. They are commonly used in low to medium-pressure applications.

U-Cup Seals: They have a U-shaped cross-section that provides a tight seal against the rod. They are best suited for high-pressure applications and provide excellent wear resistance.

Selecting the appropriate seal material is crucial for the optimal performance of hydraulic cylinders. The choice depends on various factors, including the operating environment, pressure, temperature, and fluid compatibility.

Preventing Contamination: Wiper Seals and Their Vital Role

Contamination is a common issue in hydraulic systems, leading to premature wear, reduced efficiency, and potential failure. Wiper seals, also known as scrapers, play a vital role in preventing contaminants from entering the cylinder and damaging internal components.

Wiper seals are installed on the external side of the cylinder, where the rod exits the housing. Their primary function is to scrape off dirt, dust, and other debris from the rod as it retracts into the cylinder. By preventing contaminants from entering the hydraulic system, wiper seals enhance the longevity and reliability of the cylinder.

Wiper seals are typically made from durable materials like polyurethane and nitrile rubber. Polyurethane wipers offer excellent abrasion resistance, making them suitable for applications with heavy contamination. These are ideal for harsh environments with high levels of contamination, such as construction and agriculture, due to their excellent wear resistance. Nitrile rubber wipers provide good flexibility and are effective in environments with moderate contamination levels. These are suitable for applications with moderate contamination, such as industrial machinery, due to their flexibility and resistance to hydraulic fluids.

Ensuring Longevity and Performance of Hydraulic Seals

The performance and longevity of hydraulic seals directly impacts the efficiency and reliability of hydraulic systems. Proper maintenance and care are essential to maximize seal life and ensure optimal performance.

Regular inspections of hydraulic seals helps to identify signs of wear, damage, or contamination early. Visual checks for cracks, deformation, or fluid leaks can prevent minor issues from escalating into major failures. RHK recommends that users regularly check seals for signs of wear, cracks, or deformation to identify potential issues early. Scheduled maintenance, including cleaning and lubrication, ensures seals remain in good condition and perform effectively. We also recommend that you implement a routine maintenance schedule that includes cleaning and lubrication to keep seals in optimal condition.

Proper installation of hydraulic seals is crucial for their performance. Incorrect installation can lead to premature wear, leaks, and system inefficiencies. Following manufacturer guidelines and use of appropriate tools during installation ensures seals are correctly positioned and function as intended.

Hydraulic cylinder seals are critical components to ensure the efficiency, reliability, and longevity of hydraulic powered systems. Understanding the different types of seals, their unique roles, and the importance of material selection is key to optimizing equipment performance. By preventing contamination and ensuring proper maintenance, hydraulic seals can significantly enhance the lifespan of hydraulic cylinders.

For those seeking expert guidance and top-quality hydraulic seals, RHK Hydraulics offers comprehensive hydraulic cylinder services, custom hydraulic cylinder manufacturing, and repair solutions. As one of the leading hydraulic cylinder manufacturers in Canada, RHK Hydraulic Cylinder Services Inc. is dedicated to providing reliable and durable hydraulic solutions tailored to meet the unique needs for each application.

Hydraulic cylinders are vital to various industrial applications, and ensuring they operate efficiently and reliably is essential. By understanding the different types of hydraulic cylinder seals and how to maintain them, you can optimize the performance of your businesses&#; hydraulic systems. Investing in high-quality seals and following best practices for maintenance and installation will help you achieve long-lasting, reliable operations of your equipment.

Contact our team at RHK Hydraulics a call for all of your hydraulic needs, from manufacturing to repair! Contact us today to learn more.

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