Elastomeric seals are used in a wide range of applications, but even the best quality polymers can fail. This is usually the result of abrasion, chemical attack, or gradual expansion/contraction due to extreme operating temperatures. Polymer spring energy storage seals are a reliable solution for these harsh operating conditions. Spring-energized seals are composed of high-performance elastomers, typically polytetrafluoroethylene (PTFE). These seals are designed to provide a smooth, energy-efficient operation.
This highly durable polymer jacket is reinforced with a corrosion-resistant metal spring energizer that supplies a constant load to the lips, creating a reliable gas-tight barrier against all contacting sealing interfaces. Seals that are in the springtime are an effective combination of elastomeric and metallic sealing concepts.
When choosing a material for a spring jacket, fluoroplastic compounds and engineered plastics are both options, but PTFE is generally considered to be the best because of its exceptional durability and tolerance to extrusion. Virgin poly ether ether ketone (PEEK) is sometimes recommended for back-up rings and high-temperature applications, while UHMW-PE is valuable for dynamic sealing applications with high wearing forces.
However, the wide variability of PTFE-based compounds means there is usually a lubricated, modified, or proprietary solution appropriate for all working conditions. There are different types of energizers for Spring. Depending on the type of fluid the energizer is used in, it can have different effects. The performance of stainless steels is good in most cases, but knowing the grade of steel is important in order to get the longest life out of the spring-powered seal.
Functions of Energizers
When a spring-energized seal is installed in a cavity, it is subject to radial compression from the surrounding walls. This spring-loaded mechanism energizes the lips, which causes them to press firmly against the gland walls to create a very strong leak-tight barrier. The radial tension in the installation sealant ensures a reliable seal from start to finish, without any system pressure required. When pressure is applied, the jacket becomes more energized and the seal force increases.
The sealant has excellent low- and high-pressure sealing capabilities, and is assisted by spring-energizers in combatting seal extrusion at high temperature/pressure. This is a form of failure that can be seen as a nibbling or shaving of seal materials over time as a result of repeated stress. It is important to note that additional factors can affect seal extrusion, such as the size of the extrusion gap and the surface speed.
Back-up rings with specialist spring energizers can provide reliable performance in applications involving complex extrusion phenomena.
Where Spring Energizers are Most Useful ?
Sealed springs are most valuable where leakage is a problem and in extreme environments, such as cryogenic temperatures. The results of these space launch vehicle applications have been found to be relevant to aviation in high-temperature jet engines. The seals are versatile and have been used in many different industries, such as life science (robotics, liquid chromatography, in vitro diagnostics, and microsurgical tools), energy (onshore/offshore ball valves and LNG loading arms), and industrial (valves and pumps). Spring loading can be designed to handle critical low friction requirements in dynamic applications or extreme high loading often required for cryogenic sealing. The springs used in your device are made from corrosion-resistant metals, such as the 300 series.
A stainless-steel spring helps to energize the seal when the pressure is low enough to not fully activate the lips. The spring also compensates for variations in stuffing box tolerance and normal seal wear. The metal spring is more accurate than devices such as O-rings when it comes to controlling friction.
Types of Springs:
There are three different types of springs:
- Light Spring
- Medium Spring
- Heavy Spring
Each has a corresponding load rating to meet the exact linear friction or torque requirements. In dynamic applications, the spring expands to counteract seal wear while continuing to provide load.
The spring system maintains the seal lips in a compressed state, without taking a compression set or becoming too soft or hard, in conditions involving thermal cycling. The flexible spring allows for a large tolerance range, which is helpful when dealing with hardware misalignment and eccentricity. This allows the spring to work without causing extra friction or the inability to seal.
These Spring-Energized Seals are designed with unique material properties that provide design engineers with new solutions to difficult applications. Many of these capabilities are the result of the materials used in the seal. Seal jackets are made from low-friction PTFE and blends, which are chemically inert, extrusion resistant, and capable of operating over a wide temperature range. The polymer’s lack of resilience is overcome by a spring-loaded metal component that is corrosion resistant. The spring energized seal solves many of the problems associated with O-rings or other elastomeric seals. When selecting an elastomeric seal to handle a variety of solvents, it is important to review the compatibility of the elastomer in each solvent. In many cases, no elastomer is ideal for the intended range of fluids.
In many cases, none of the commonly used elastomers are suitable for the intended range of fluids. The problem becomes even more difficult when the operating temperature exceeds about 500 degrees Fahrenheit. If you are considering using an elastomer for a rotary or reciprocating application, you will have a difficult time choosing one.
There are many factors to consider.
- With spring energized PTFE seals, you can be sure that the seals will be compatible with virtually all industrial chemicals and solvents, even at elevated temperatures and pressures.
- With spring energized PTFE seals and O-spring the durability of the products is not compromised.
- The spring energized seals are the smart way to ensure energy efficiency
- In dynamic service, you don’t have to worry about slipsticks or sticking elastomers.
The Spring energized seal is actually designed to handle a variety of applications. The Spring-Energized O-ring seal are made to ensure the durability and the safety of the products these are used in.