Materials are selected on the basis of their chemical and thermal stability relative to the medium to the sealed. Care should also be taken to determine whether the anti-corrosive properties of the metallic components are sufficient.

Pro­tec­tion against cor­ro­sion

In the standard models, the reinforcing ring is of phosphatized, deep-drawn sheet and the radial spring from size 111 or 211 upward of bright-drawn spring strip steel. Seal sizes 100 to 110 and 200 to 210 are equipped with radial springs of stainless spring strip steel as standard. From size 111 or 211 upward, the seals can also be equipped with stainless radial springs upon request. Radial springs of spring-hard brass sheet are frequently employed for special sizes and designs.

De­pend­abil­ity of seal

In order to ensure a dependable sealing effect, the pressure exerted by the medium to the sealed may not lift the sealing lip up off the mating surface. The maximum permissible pressure per seal size can be seen in the tables on pages VI, VA, and DI. It is only permissible to increase the sealing lip prestress by increasing the spring force if a dependable seal cannot be ensured in any other manner. Otherwise, an increase in the sealing lip prestress would result in unnecessary friction and heat-up, leading to
unnecessary wear.

Pe­riph­eral and ro­ta­tional speed

In order to avoid unnecessary heat-up and wear of the sealing lip, limit the peripheral speed at the sealing lip in accordance with the selected seal material. The permissible rotational speeds for Perbunan® and Viton®, by seal size, can be seen in the tables on pages VI, VA and DI. The diagram (down) provides a rapid overview for per­mis­si­ble speedPerbunan®.


Fric­tion and dis­si­pated out­put

In order to determine the required drive output the coefficient of friction at start-up and the dissipated output under normal operating conditions is necessary. During start-up, static friction is initially encountered, followed by dynamic friction. The coefficient for static friction is assumed to be μo = 0.48, the coefficient for dynamic friction is a maximum of p = 0.24 (0.12–0.24). These figures apply for lubricated steel/PERBUNAN and steel/VITON sealing surfaces.

MRO = 5 · 10-4 · Fa · dm · μo [J]

Dissipated output:
PR = 52,5 · 10-6 Fa · dm · n · μ [W]

Fa = Contact pressure force (sealing lip) [N]
dm = Mean diameter of sealing lip [mm]
n = Speed [min-1]
μo = Coefficient of friction, static
μ = Coefficient of friction, dynamic

Coefficient of friction dissipated output

Per­mis­si­ble pe­riph­eral speed

The peripheral speed at the sealing lip may not exceed the following values:
  • Type VI: Perbunan® 20 m/s, Viton® 30 m/s
  • Type VA: Perbunan® 10 m/s, Viton® 15 m/s
  • Type DI: Perbunan® 9 m/s, Viton® 13 m/s

These values assume sufficient lubrication and heat dissipation at the sealing surface. Should these conditions not be provided, the limits shown at the left must be appropriately reduced, in accordance with the specific application.

Des­ig­na­tions em­ployed

Peripheral speed: v  (m/s)
Speed:         n  (min-1)
Axial force:   Fa  (N)
Pressure:    p  (Pa)
Moment of friction: MRO  (J)
Dissipated output: PR  (W)
Width/length, Diameter: b, l, d  (mm)
Coefficient of friction, static: μo    ( )
Coefficient of friction, dynamic : μ  ( )

Conversion of units
1 N = 0,102 kp
1 Pa = 0,102 mmWS = 10-5 bar
1 J = 0,102 kpm = 1 Nm
1 W = 1,36 · 10-3 PS