The Type 15 is recommended where minimum
leakage rates are desirable and contact with the shaft is acceptable.
The limited radial sealing gap between the
carbon ring and the shaft results in considerably less leakage than that
of the Type 5 controlled gap seal, under full operating conditions.
However, due to the design, the Type 15 will leak more at start-up, but
as operation proceeds from cold start to full temperature, leakage will
diminish greatly as the accompanying shaft growth occurs.
