Packing seal(Stuffing-Box Seal) Consists of stuffing box, flexible packing, gland and clamping bolts. The gland compresses packing material to grip the agitator shaft and sealing.

Common packing options: graphite-impregnated PTFE packing or aramid-braided PTFE packing. Housing and gland are mostly 316L stainless steel, fitted with stainless-steel or hard-alloy shaft sleeves.

Mechanical seal (Mainstream for Fermenters) Mechanical seals form sealing surfaces by end-face contact of one or multiple precision rotating and stationary rings.

Kept compressed by spring force.

Available in single-end-face and double-end-face configurations. Fermenter mechanical seal friction pairs are commonly silicon carbide-to-silicon carbide.

Silicon carbide-to-hard-alloy is also an option. Secondary sealing rings are generally FKM fluororubber. Springs and metal components are 316L stainless steel.

Hastelloy is specified for highly corrosive service.