Page 407 - Centrifugal Pumps 2E

372 Centrifugal Pumps: Design and Application

Table 17-2
Frequently Used Seat Face Materials
and Their PV Limitations

developed for a wear rate that provides an equivalent seal life of two
years. A PV value for a given application may be compared with the lim-
iting value to determine satisfactory service. These values apply to aque-
ous solutions at 120°F. For lubricating liquids such as oil, values 60% or
higher can be used.
Three separate tests are performed by seal manufacturers to establish
performance and acceptability of seal face materials. PV testing is a mea-
sure of adhesive wear. Abrasive testing establishes the relative ranking of
materials in a controlled environment. Operating temperatures have a
significant influence on wear. A hot water test is used to evaluate the
behavior of seal face materials at temperatures above the atmospheric
boiling point of the liquid.