Seals & O-Rings

NBR is the cheapest and fine for clean air and mineral oil up to about 100 °C. FKM (Viton) handles most solvents and up to roughly 200 °C and is the default for vacuum service. FFKM (Kalrez, Chemraz) is for aggressive plasma chemistry and high bake temperatures — several times the price, so use it only where FKM actually fails.

On a KF or ISO joint, usually yes if it is clean, not permanently compressed and shows no cracks or swelling. On a CF joint the copper gasket is single-use and must be replaced. In either case, never reuse a seal that has seen plasma or aggressive process gas.

Both. Give us the pump model and part number if you have it, or the inner diameter, cord diameter and material if you are matching a loose seal. A photo next to a ruler is usually enough to identify a standard size.

No. A tip seal is the polymer strip along the edge of a scroll pump's scroll, doing the job that oil does in a wet pump. It is a wear part with a defined replacement interval and is model-specific — it is not interchangeable with any O-ring.