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O-Rings

Typical Interference and Stretch by Application

\[ \text{Stretch} = 100 \times \frac{ID_\text{Gland} - ID_\text{O-Ring}}{ID_\text{O-Ring}} \]
\[ \text{Interference} = 100 \times \frac{OD_\text{O-Ring} - OD_\text{Gland}}{OD_\text{O-Ring}} \]

In most glands the free O-ring size does not exactly match the installed geometry. Internal seals may stretch the O-ring over the gland diameter, while external seals may rely on the O-ring outside diameter being slightly larger than the gland diameter.

ApplicationTypical Allowance
Face Seal (Internal Pressure)0-3% Interference
Face Seal (Internal Vacuum)0-5% Stretch
Rod (Static)0-2% Interference
Piston (Static)0-5% Stretch

Canyon Components

Typical Compression

Compression, often called squeeze, is what creates the initial sealing contact between the O-ring and the gland surfaces. Too little squeeze can leave an unreliable seal; too much can increase friction, wear, assembly force, and the risk of material damage.

\[ \text{Compression Ratio} = 100 \times \frac{CS_\text{O-Ring} - D_\text{Gland}}{CS_\text{O-Ring}} \]
ApplicationMinimumTypicalMaximum
Face Seal10% Compression25% Compression35% Compression
Rod & Piston (Static)5% Interference20% Interference30% Interference

Canyon Components

Gland Fill

Gland fill compares the O-ring volume with the available groove volume after installation. Leave enough free volume for tolerance stack-up, thermal expansion, media swell, and normal deformation so the O-ring is not over-packed in the groove.

\[ \text{Fill}_\text{Gland} = 100 \times \frac{\text{Volume}_\text{O-Ring}}{\text{Volume}_\text{Gland}} \]
ApplicationMinimumTypicalMaximum
Static Seal65% Gland Fill75% Gland Fill85% Gland Fill

Canyon Components