Design Parameters Of Spring Energized Seals
Spring energized seals are a highly reliable option when standard elastomer-based and polyurethane-based seals do not meet the operational constraints, equipment parameters, or environmental conditions of your application.
The sealed outer ring of the plug seal is made of high-performance fluoroplastic compounds and engineering plastics with outstanding physical and technical properties. At the same time, the addition of the spring provides a load over the entire circumference of the seal, forming a leak proof seal between the seal ring and spring. In this combination, the spring pressurizes the sealing lip against the gland and piston rod surface for leak-free, high reliability and long life seals.
1. Standard material
PTFE is the most commonly used sealing ring material with excellent physical and chemical properties, moderate cost and good mechanical properties.
By using different fillers, the properties of the PTFE compound can be further improved, and the sealing efficiency (such as tensile strength, abrasion resistance, etc.) can be improved. However, not all fillers can be increased indefinitely, and the filler content is usually 5% to 40%.
Common filling compounds
- Bronze
- Carbon/Carbon fibre
- Glass fibre
- Graphite
- Molybdenum disulfide (Mos2)
(Other fillings for special conditions on request.)
PTFE compound material advantages:
- High temperature resistance
- Low friction
- High wear resistance
- Dry running capacity
- High PV factor
- Almost resistant to all known chemicals and solvents
- No chemical swelling when exposed to moisture or contact with fluids
2. Material & Types of Spring
From the foregoing description we know that the primary function of the spring is to provide a radial force at the sealing point of the sealed outer ring when installed in the sealed chamber. At the same time, flexibility is added to the PTFE sealed outer ring to improve eccentricity and material wear.
1) The medium, operating conditions and temperature range of the plug seal are extensive, and the spring material is also divided into various types, such as 300 stainless steel series (SS) 301, 302, 304 and 316.
2) The typical spring design in spring energized seals:
'V' spring (A)
Spiral spring (B)
Helical spring (C)
Continuous contact spring (D)
3) The selection of spring should generally refer to the working condition machines, such as speed, friction, operating temperature and media.
The friction load generated by the seal is the radial load of the selected spring, and the system's pressure load is a direct result of the friction coefficient of the selected material.
Therefore, the spring load can be customized to meet the special low friction requirements of dynamic applications. Low temperature or low temperature sealing applications may require extremely high spring loads. The spring compensates for the heat shrinkage of the outer ring of the seal, resulting in a tight seal.