GAP CHART
Back-up Rings are installed on the downstream side of an
O-Ring to help prevent premature failure and leakage. If the
sealing ring cannot resist increasingly higher pressure, part
of the seal will be forced into the diametrical gap. Back-up
rings are used to block the clearance gap and provide support
for the seal.
Applications which fall on the right side of the curve
require use of back-up rings.