O-ring SCHAERER Spare Parts 3303985000

An O-ring forms a flexible seal between two mating surfaces by compressing slightly when installed. The elastic material fills microscopic gaps, blocking liquid or steam while allowing the parts to move or expand without leaking. This design is used wherever a joint must hold pressure yet remain serviceable: water inlet valves, steam wands, boiler ports and group heads in coffee machines.

The operator fits the O-ring into a groove cut to its exact cross-section. Once seated, the ring is held in place by the surrounding metal; no adhesive is needed. When the joint is tightened, the O-ring deforms just enough to create a leak-proof barrier. Over time, heat and cleaning chemicals harden the material, so the ring is replaced as part of routine maintenance to keep the seal effective.

This O-ring is made from EPDM rubber with a 70 Shore A hardness, a grade chosen for its balance of flexibility and resistance to hot water and steam. The black colour is standard for food-safe EPDM in catering equipment. Its dimensions—2.9 mm outer diameter and 1.78 mm cross-section—match the grooves in SCHAERER coffee and espresso machines, ensuring a precise fit without stretching or pinching.

Cleaning is limited to wiping the ring with a damp cloth before installation; no solvents are required. Store the spare in a cool, dry cupboard away from direct sunlight to prevent premature ageing of the rubber.

Genuine SCHAERER spare part, article 3303985000, listed under seals and gaskets in the coffee-equipment catalogue.