Goulds Pumps ANSI FAMILY IOM (ATEX Compliant) - IOM - Manual (Page 136)

Alignment
A shaft alignment is not required when using the C-Face
adapter. The rabbetted fits of the motor to the adapter
and the adapter to the bearing frame automatically
aligns the shaft to within the specified limits below.
The C-face motor adapter is intended for end users
who need fast pump installation. A C-face adapter
can attain a nominal alignment of 0.007 inches TIR.
However, due to the stack up of machining tolerances
of the various parts, the alignment can be as high as
0.015 inches TIR. Using a flexible, elastomer
coupling like a Rexnord ES or Wood's Sureflex will
provide acceptable pump and motor life under these
alignment conditions.
To achieve the best Mean Time Between Pump
Maintenance (MTBPM) requires shaft alignments of
less than 0.002 inches (0.05mm). End users who
require high pump and motor reliability are better
served by using a foot mounted motor on a precision
machined baseplate and performing a conventional
alignment.
134
ANSIFAM IOM - 5/08