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The following definitions are intended to give basic understanding of the terms
specifications, may have specific meaning of certain terms that may be different
from their common usage - in such case the terms should be interpreted in the
context of the standards, or specifications, being referred to.
z - (lower case) symbol normally used to indicate the number of vanes of an
impeller, such as used in the formula for calculating the impeller eye area.
Z - (upper case) symbol normally used for calculating pump hydrodynamic size,
a hydraulic index that is similar to specific speed.
Z - the third coordinate in a three-dimensional projection. In a pump's Forces
and Moments (F&M) the Z force normally refers to the force in horizontal plane
in the direction perpendicular to the pump shaft.
Zeron - a highly alloyed super duplex stainless steel material used in pump
components in aggressive environment service. Zeron is a registered trademark
by its owner, and is claimed to have high resistance to pitting, crevice corrosion,
and stress corrosion cracking.
Zero percent head loss NPSHR (NPSH0) - the net positive suction head
required (NPSHR) by a pump that will result in zero or no head loss from its
original performance curve obtained when the pump is tested with ample
NPSHA. The standard criteria for establishing NPSHR is based on three percent
head loss, or NPSH3. NPSH0 is sometimes specified in high energy application
to provide the pump with extra margin of protection from cavitation damage.
Some companies have developed an empirical factor to be applied on a known
NPSH3 of a pump to estimate its NPSH0.
Zymaxx - a commercial brand of composite material containing carbon fibers
used in making pump parts such as bearings, bushings, wear ring inserts, etc.,
comparable to those made of Peek material. Zymaxx is a registered trademark
by its owner.