clearance (2 g) of O-ring without retaining ring should be controlled as shown
in Fig. 9.4.
(2) The specifications, dimensions, and materials of O-ring must be suitable for
application types, such as larger compression ratio for face seal and smaller
compression ratio for radial seal, larger compression ratio for static seal and
smaller compression ratio for dynamic seal, larger compression ratio for reciprocating dynamic seal and smaller compression ratio for rotary dynamic seal.
(3) O-ring material must be compatible with fluid pressure. Figure 9.5 shows the
failure process of O-ring under high-pressure fluid extrusion under a radial seal.
Figure 9.6 shows the characteristic curves of the relationship between the fluid
pressure and the allowable radial clearance of three O-rings with different Shore
pressure
Fig. 9.4 Maximum diameter
clearance (2 g) of O-rings
without retaining rings
Fig. 9.5 Failure process of O-ring under high-pressure fluid extrusion under radial sealing
Fluid pressure/mPa
Extrusion zone
(Shore hardness)
Non-extrusion zone
Radial clearance/mm
Fig. 9.6 Curve of
relationship between fluid
pressure and allowable radial
clearance of materials with
different hardness
9.1 Electro-Hydraulic Servo Control Technology of Aircraft Gas Turbine Pump
63