O-ring, 15 x 2 mm – Viton, Part# 23970008 – vacstellar

Inside every Leybold Trivac pump there are small grooves and passages that need a perfect seal. This little black O-ring does exactly that.

It slides into place around a shaft, cover, or oil line. Once it’s there, it stops leaks and keeps the vacuum strong.

Viton is the material you want for these pumps. It stays soft and flexible even when the oil gets hot. Normal rubber would harden and crack after a year or two.

You usually replace these O-rings during a full service – when you change the big gaskets, the shaft seal, or do a major overhaul. They cost almost nothing, but skipping them can cause small drips or poor vacuum later.

The size is exact: 15 mm inside diameter, 2 mm thick. It fits Leybold D40BCS and D65BCS perfectly. The same part is also used in Busch R5 pumps like RD0200A, RD0240A, RD0300A and RD0360A.