Radial seals

Radial seals have one sliding friction partner seated radially around the other. the cylindrical contact surface separates the spaces at either end of the cylinder. Within limits, the partners can move axially in relation to each other without impairing the seal's effectiveness.

To compensate for wear, the seal is retightened by altering the radial position of one or both of the partners. Because this changes the geometry of respective part and therefore the forces applied, soft materials have to be used. In cases, too, radial sealing elements have to be lubricated to prevent overheating.

The radial seal category includes rotary shaft seals, lip seals, and stuffing boxes. Because agitator shafts often display serious radial deflection, radial seal rings are unsuitable and lip seals are usable only for undemanding applications. Though stuffing boxes are still used quite widely for sealing agitator shafts, they are now being replaced by mechanical seals to an increasing extent.