Without the necessary closing force for the sliding face generated by the spring backing, an unpressurized mechanical seal would open (load factor k). The most common types of spring backing are steel springs, which come in diverse forms (spring types), laminated bellows and rolled bellows. Elastomer materials or magnetized rings are able to perform the same duty, but their suitability as spring backing is limited.

For reasons of durability, the steel springs used as spring backing for mechanical seals are manufactured almost exclusively from stainless spring steel or high-corrosion-resistant alloys. With severely polluted products or heavy chemical attack, the spring backing can be provided with an additional protection or enclosure.

Mechnical seal with a multiple spring in contact with the product

Mechnical seal with enclosed spring (illustrated is a wave spring). Being situated outside the product chamber, the spring is also protected against chemical attack