be used with mineral-base hydraulic fluid.
Examples of some of the
different kinds of seals used in plumbing systems are shown in Figure
2-20 and discussed in the following paragraphs.
Seals Used in Plumbing Systems.
O-Rings. In Army aircraft, the O-ring is the most commonly used
type of hydraulic seal.
It is designed to control leaks against
pressures coming from any direction and can be used where there is
either rotative- or linear-relative movement between parts.
ring can also be used between nonmoving parts to eliminate leaks such
as in the joint between two parts of a housing.
When used in this
manner the O-ring is called an O-ring gasket.
When the pressure to be retained by an O-ring
exceeds 1,500 psi, a backup ring is used in the groove along with the
O-ring. Backup rings prevent O-ring material from extruding into the
clearance gap between the sealed surfaces.