'O' Ring Guide

How to use this guide
For new applications
1) Refer to Design sections, pages
27-31, for guidance with regard to
applications.
2) For aerospace equipment, select ‘O’
ring from Aerospace Sizes to BS ISO
3601-1, pages 17-20.
3) For general metric equipment, select
‘O’ ring from Chart 72, pages 21-22.
4) If the metric size you require is not
available from Chart 72, then select
from the metric columns in Chart 50,
pages 13-16.
5) For general inch sizes, use Chart 50, or
Chart 17000 on page 23.
Selecting a back-up ring
One or more back-up rings are used to
prevent extrusion of an elastomeric ‘O’
ring under arduous operating conditions.
Our standard back-up rings are machined
in PTFE and normally supplied in single
turn or spiral form. See page 12 for more
details on back-up rings.
Back-up rings for use with James
Walker ‘O’ ring number
Refer to How to order section on page 7
for precise specification details relating to
back-up rings for Chart 50, Chart 72 and
Chart 17000 applications.
Back-up ring for use with existing
‘O’ ring
1) Identify appropriate Chart and part
number for existing ‘O’ ring. (Note: If
a standard ‘O’ ring has been used on
a non-standard shaft or cylinder — ie,
compressed or stretched into place
— the equivalent standard back-up
ring must not be used as it cannot be
stretched or squeezed in the same way.)
2) Refer to How to order section on page 7
for precise specification details.
Back-up ring for use with non-standard
size ‘O’ ring
Please contact our Technical Support
Team for recommendations on the correct
back-up ring.
Back-up ring for a new application
1) Select the ‘O’ ring you require from
our Charts, using the method outlined
earlier on this page.
2) Refer to How to order section on page 7
for precise specification details.
To order or get further details, call your local contact shown on rear cover or listed at www.jameswalker.biz 5