L3 / D4
A guide line for determining pump shaft stiffness where the length
of the shaft is compared to its diameter. This number should be
below 60 in imperial units and 2.0 in metric units.
Labyrinth seal
A non contacting seal utilizing a tortured path for the escape
of the fluid. Utilizes a series of pressure drops to reduce the
leakage.
Lantern Ring
A device used to supply lubricant to packing. Usually located
in the middle of the packing ring set.
Linear pressure drop
A straight line pressure drop across the lapped seal faces. Seldom
happens.
Line bearings
Position the rotor or shaft radially. Normally of the sleeve
type.
Line bored
When the drilling or boring is done on a jig that insures every
component is in a straight line.
Lip Seal
See grease seal.
Low flow
A condition that can cause excessive heat inside the pump volute.
A temperature rise of 10?C (18?F) across the operating pump is
considered excessive. Usually caused by throttling a pump discharge
valve.
Lubricant
Any fluid that will maintain a film thickness of one micron or
more at its operating temperature and load.