Bring On The "Spring" Q&A

What makes spring energized seals so efficient?

Spring energized seals are high performance seals, energized by a spring. Needed for the most demanding applications, energized PTFE seals are extreme-temperature resistant, high-pressure, chemically inert, consistent, and dynamic.The internal energizing spring makes the thin, flexible PTFE sealing jackets resilient when applying a load to the sealing element at low pressures. The "U" shaped jacket allows fluid pressure to energize the sealing lips, so total sealing pressure rises with increasing operating pressure spring force. As the given system’s pressure increases, the spring engages to create a highly efficient seal against the mating surface. The spring provides permanent resilience to the seal jacket and compensates for jacket wear, hardware misalignment, or eccentricity.

What applications are the most ideal for spring energized PTFE seals?

The most common applications in which spring energized seals are used include hydraulic actuators, aircraft engines, brake systems, valves, fire suppression systems, drones, chemical pumps, compressors,

cryo coolers, food processing equipment, mechanical seals, oil field equipment, and aircraft engines. Customers seeking to reduce their overall costs while maintaining applications such as these benefit from Colonial Seal’s absence of tooling charges, minimum order quantities, and design costs. High quality spring energized seals from Colonial Seal have also been proven to improve reliability and reduce downtime.

What are the design elements of these seals?

Spring Energized Seals have three main design characteristics. These include an application specific U-shaped seal profile, spring geometry suited to the particular application, and proven high-performance polymers. Standard products are available from 2 mm up to 2500 mm (8' 2") in diameter whereas customizations may be manufactured in intermediate sizes, inch (imperial) sizes, or special geometries. All performing under the same operating principle, seals only differ in their profile form and type of metallic spring used.

Spring energized standard seals can be used at pressures up to 3,000 psi and operate in the range of –280 to 500oF. Available in a range of geometries and designs, these seals allow the optimum profile to be selected for each application. All of these maintain low friction, long service life, and can be used for rotary, reciprocating and oscillatory motions.

Custom spring energized seals can handle up to 60,000 psi and operate in the range of –400 to 600oF. Custom spring energized seals offer a wide range of PTFE compounds to choose from and can be manufactured in polyethylene based material when required. Functional parameters must be chosen before choosing the best seal for a customer's application. Quality of the mating surface has a significant effect on the function and service life of the sealing system and is an important aspect to consider. They can be produced from a wide range of PTFE based compounds and are specially formulated for sealing elements.

What materials are used to create these seals?

Available jacket materials include Virgin PTFE (recommended for most static applications for pressures below 3,000 PSI), Graphite filled PTFE (recommended for dynamic applications for pressures also below 3,000 PSI), Carbon Filled PTFE (recommended for dynamic applications for pressures below 5,000 PSI), Polymer Filled PTFE (recommended for dynamic applications and long life for pressures below 3,000 PSI), and Rubber Elastomer. Nitrile, FKM, and FFKM are also available for use as jacket materials.  

Available spring materials include 301 SS which is recommended for general applications and temperatures up to 400oF. Elgiloy is recommended for greater chemical and temperature resistance with temperatures up to 600oF, 17-7 PH SS is standard for coil springs in general applications with temperatures up to 500oF, and rubber elastomer is used for rubber O-rings (serving as the energizer that is also referred to as PolyPacks or Loaded U-cups.)

What benefits can I expect as a result of using spring energized seals?

Design of components such as hydraulic and pneumatic cylinders (in all industries) can benefit from the offerings of spring energized seals. These benefits include excellent leak tightness, high resistance to wear, no extrusion into gaps, withstanding aggressive and abrasive process media, very good temperature capabilities, low friction, compact form, and simple installation.

How does my load affect the type of spring my seal should use?

Coiled springs are most ideal for a seal that is constantly receiving a compressive load regularly. Cantilever springs (also known as leaf springs) are used when a seal is in an environment where the load is constantly rising and falling. A helical spring falls somewhere in between these and is often used for critical oil and gas applications.

What factors will influence my spring energized seal’s performance?

Factors influencing seal performance include hardware preparation (surface finish and hardness), operating conditions, lubrication, frictional considerations, spring load vs. deflection, and extrusion gap / radial clearance. These must be addressed with your seal design consultant during the planning stage to ensure maximum reliability of your spring energized “Colonial” seals! Colonial Seal Company works closely with OEMs to ensure that the process of material selection, first article sampling, production, and application of sealing solutions meets their rigorous demands. The company has partnered with a network of highly qualified engineering professionals to ensure that your custom sealing solutions will be met. 

The above information is provided only as a guide in helping you select the type of spring energized seals to maximize efficiency of your applications. Please call Colonial Seal Company at 856-432-0012 or email sales@colonialseal.com if you have any concerns about the optimal spring required for your specific application.

Founded in 1994, Colonial Seal Co. is headquartered in Westville, New Jersey. Colonial Seal specializes in oil & grease seals, hydraulic seals, rotary shaft seals, mechanical seals, rubber molded products and gaskets. Through a global network of manufacturers, Colonial Seal can produce custom seals designed for a client’s unique sealing applications. Colonial Seal Company is ISO 9001:2008 certified.