Gland Dimensions

Please select an industry for design assistance or view the reference charts and design tips below:

Proper Squeeze

•Compression expressed as a percentage of the free-state cross-sectional thickness
     (O-Ring C/S) - Gland Depth
     (O-Ring C/S)
•Face Seal:                    20-30%
•Static Male/Female:     18-25%
•Reciprocating:              10-20%
•Rotary:                         0-10%

Stretch

(Groove Diameter) - (O-Ring ID)
(O-Ring ID)
•General rule is 0-5%
•Excessive stretch can overstress material, thin cross section, and reduces % squeeze
•% cross section reduction due to stretch about half of the % ID stretch

Pressure vs Clearance

•Excessive clearance can result in seal extrusion
Durometer vs. Pressure and Clearance Gap Chart

Tolerances

•Have to be considered for O-Ring and the gland
•Affects squeeze and affects pressure rating
•Less a factor on larger cross sections

Surface Finish

•Seal material must fill in voids in surface.
•Static surfaces
    –32 rms to seal liquid
    –16 rms to seal gas
•Dynamic Surfaces
     –8 to 16 rms
•Too rough of a surface can result in abrasion or spiraling, even with a static seal

Sharp Corners

•Can cause damage during seal installation

Gland Fill

•Gland volume vs. O-Ring volume
(O-Ring Volume)
(Gland Volume)
•About 25% void space or 75% nominal fill
•Need space in groove to allow for volume swell, thermal expansion, and increasing width due to squeeze
•Narrower groove for sealing vacuum or gas
•O-Ring can get squeezed out into clearance gap or get squeezed in two directions

Eccentricity & Side Loading

• Too much squeeze on one side and not enough on the other or none at all
•Can open too wide a clearance gap and result in extrusion of one portion of seal

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