O-ring, 18 x 2.0 mm – Viton, Part# 320177

This is a Viton O-ring. Its part number is 320177 . An O-ring is a simple loop of elastic material. Its shape is a perfect circle. When you look at a cross-section, it looks like the letter “O”. That is where the name comes from.

You place this O-ring into a groove between two metal parts. When you tighten the parts together, the O-ring gets squished. It fills the tiny gap completely. This creates an airtight, leak-proof seal . This O-ring measures 18 mm on the inside and has a thickness of 2.0 mm .

This O-ring is made specifically for these Pfeiffer DUO pump models :

• Pfeiffer DUO 125

• Pfeiffer DUO 255M (Index C)

If you own either of these pumps, this is the right O-ring for you. It is also included as a standard component in the Seal Kit for the DUO 125 (Part # PSK025) , which contains one of these O-rings