The spring-energized seals are essential sealing elements designed to seal rotating shafts in machinery and equipment where oils, lubricants or other operating fluids are used.
The correct selection of a spring-energized seal depends on specific operating conditions, particularly the type of sealed medium, operating temperature, shaft peripheral speed, pressure and other parameters of the application.
A standard rotary shaft seal consists of a metal reinforcement ring, an elastomer sealing element and a tension spring. Depending on the requirements of the application, it can also be equipped with an additional dust lip for protection against contamination or supplied in a design without a dust lip.
Rotary shaft seals are standardized according to ČSN 02 9403 or DIN 3760.
Standard materials:
Rubber material of radial seals:
| Basis of elastomer | DIN ISO 1629 | Hardness [Shore A] | Colour | Temperature [° C] |
| Acrylnitrile-Butadiene-Rubber | NBR | 70 | black | – 40 up to + 100 for a short term + 120 |
| Fluorine-Rubber | FPM | 80 | brown | – 30 up to + 200 |
PTFE material of WEPO and WCP21 rubbers:
| Basis of elastomer | DIN EN ISO 1043- 1 | Filler | Hardness [Shore A] | Temperature [° C] | Form |
| Acrylnitrile-Butadiene-Rubber | PTFE | carbon/graphite | 62 | – 30 up to + 205 | WEPO |
| Fluorine-Rubber | PTFE | glass fibre/MoS2 | 60 – 80 | – 90 up to + 250 | WCP21 |
Special materials:
| Basis of elastomer | DIN ISO 1629 | Hardness [Shore A] | Colour | Temperature [° C] |
| Silicone-Rubber | VMQ | 70 | red | – 50 up to + 200 |
| Acrylate-Rubber | ACM | 70 | black | – 25 up to + 150 |
| Ethylene-Propylene-Diene-Rubber | EPDM | 70 | black | – 40 up to + 130 |
The shaft’s surface speed
The shaft’s surface speed corresponds to the slide speed of the mutual movement of sealing surfaces.
Working pressure by standard spring-energized seals
| max. pressure [bar] | rpm [min-1] | max. speed [m/s] |
| 0,5 | do 1000 | 2,8 |
| 0,35 | do 2000 | 3,15 |
| 0,2 | do 3000 | 5,6 |
Basic types:
- type WA
- type WAS
- type WB
- type WBS
- type WC
- type WCS
- type VIA
- type VIAS
Special types:
- type WAO
- type WBO
- type WAD
- type WBD
- type WCP21
Radial seal – type WA
– The WA shape has its external mantle of elastomer, which provides a very good static sealing.
– Corrosion of face side does not occur.
– More frequent exchange of the seal will prevent the damage of the seal seating hole.
– Designated for sealing of gaseous or thin liquid media.
Material :
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 1
Radial seal – type WAS
– With dust cap against impurities and danger of corrosion
Material :
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 12
Radial seal – type WB
– It is characteristic for a metal external mantle.
– It secures firm and precise seating in a case.
– Tolerance of the seating hole is required so as to reach the sealing on the external mantle.
– Good quality of the mantle surface is necessary.
Material :
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 12
Radial seal – type WBS
– With dust cap against impurities and danger of corrosion
Material:
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 12
Radial seal – type WC
– Metal layer with a reinforcing cap.
– Packing and installation as with the WB.
– Used under especially heavy operation conditions, in rolling mills, for farming and logging machines, in windmills.
– Due to its increased stiffness, this radial seal is suitable under heavy-duty installation conditions of larger dimensions.
Material:
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 12
Radial seal – type WCS
– With dust cap against impurities and danger of corrosion
Material:
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 12
Radial seal – type VIA
– Radial seal with viton mantle and with metal reinforcing ring.
– The FPM material is more suitable for high temperatures, high speeds, and resists chemically aggressive media.
Material:
– FPM 80
– Colour: brown
– Reinforcing ring: plain steel
– Spring: stainless and acidproof steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -30 up to +200
– speed [m/s] : ≤ 35
Radial seal – type VIAS
– With dust cap against impurities and danger of corrosion
Material:
– FPM 80
– Colour: brown
– Reinforcing ring: plain steel
– Spring: stainless and acidproof steel
Operation values:
– pressure [MPa/bar] : ≤ 0,05/0,5
– temperature [°C] : -30 up to +200
– speed [m/s] : ≤ 35
Radial seal – type WAO
– It has a grooved external mantle of elastomer, metal reinforcing ring and sealing lip without spring.
– Advantage: low friction.
– The external mantle of elastomer enables good static sealing and offers good accommodation of the thermal expansion.
– Upon higher roughness secures better sealing properties for liquid or gaseous media.
Material:
– NBR 70
– Colour: green/black
– Reinforcing ring: plain steel
Operation values:
– pressure [MPa/bar] : ≤ 0/0
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 6
Radial seal – type WBO
– Radial seal with metal external mantle, without spring.
Material:
– NBR 70
– Colour: green/black
– Reinforcing ring: plain steel
Operation values:
– pressure [MPa/bar] : ≤ 0/0
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 6
Radial seal – type WAD
– Radial spring with two sealing lips and external rubber mantle.
– Especially for sealing two media or heavy pollution from outside.
Material:
– NBR 70
– Colour: black
– Reinforcing ring: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,03/0,3
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 6
Radial seal – type WBD
– Radial spring with two sealing lips and external rubber mantle.
– Especially for sealing two media or heavy pollution from outside.
Material:
– NBR 70
– Colour: green/black
– Metal case: plain steel
– Spring: plain spring steel
Operation values:
– pressure [MPa/bar] : ≤ 0,03/0,3
– temperature [°C] : -40 up to +100
– speed [m/s] : ≤ 6
Type WCP21
– Radial seal with the sealing lip of PTFE and with rubber pre-stressing ring, that are installed between two metal cases.
– The PTFE’s very low friction coefficient prevents stammering, reduces start-up resistance, and is suitable on dry run or on insufficient lubrication.
– Applicable for higher speeds, higher pressure load, and for higher temperatures.
– For sealing aggressive chemicals (excellent technical stability of PTFE).
– Various layouts feature one or two lips.
Material:
– razor edge sealing: PTFE + fibreglass / MoS2
– Colour: grey
– Metal case: stainless and acidproof steel
– Rubber part: FPM
Operation values:
– pressure [bar] : 5 bar / 10 bar / 25 bar
– temperature [°C] : -90 up to +250
– speed [m/s] : ≤ 40
Catalogue Freudenberg EN – standard types
For more information about spring-energized seals or radial seals do not hesitate to contact us.