LANTERN RING
A ring added to a packing set to assist in the introduction of a flush fluid to the stuffing box. This ring is usually made of plastic or metal.
LATERAL DEFLECTION OR LATERAL MOVEMENT
The relating displacement of the two ends of the expansion joint perpendicular to its longitudinal axis. Lateral movement is usually caused by the thermal expansion of the ducting system and measured in inches or millimeters.
LATERAL OFFSET
The offset distance between two adjacent flanges or faces. Can be due to misalignment, equipment settling, or by design to compensate for excessive displacement in the opposite direction during cycle.
LATTICE BRAID®
A Garlock trade name for a type of braided construction. In this method, the yarn is braided in an interlocking weave, making it very difficult to unravel. This construction yields a dense, tightly woven packing material having a square cross-section. Other packing manufacturers have different names for this braiding method.
LEAKAGE
An escape of gases or liquids from a piece of equipment.
LEAKAGE RATE
The quantity of fluid passing through (or around) a seal in a given period of time.
LIP DIAMETER
The inner diameter of the seal lip, measured with the spring installed.
LIP FORCE
The radial force exerted by an extension spring and/or lip of a seal on the mating shaft. Lip force is expressed as force per unit of shaft circumference.
LIP HEIGHT
The axial distance from the outside seal face to the toe face.
LIP ID TO ID ECCENTRICITY
See: Radial Wall Variance.
LIP INTERFERENCE
The tendency for a seals actual dimension at the lip area to be smaller than the ID or larger than the OD sealing surfaces.
LIP OPENING PRESSURE
The pressure necessary for flowing air at 10000 cm3/m between the contact surface of a radial lip seal and shaft-size mandrel under the following conditions: the seal case outer diameter clamped to be concentric with the mandrel and the pressurized air applied to the outside lip surface.
LIP SEAL
Lip seals have a pronounced lip-type design and rely on this lip surface to provide a seal under pressure. Also known as pressure activated.
LIVE LOADING
The use of Belleville spring washers on packing gland bolts to reduce load loss over time.
LUBRICANT STARVATION
Lack of proper lubrication at the seal interface which may cause premature wear and early failure.
LUBRICATION
The use of a liquid or fluid to reduce the friction, heat or wear between two surfaces where movement is taking place.