Standard Design
The PTFE insert is rigidly held into the body and ‘energized’ onto the spherically machined disc by means of the secondary seat which is fixed into the body by a bolted in retaining ring. This version is used in low temperature and ambient applications.
Firesafe Design
The PTFE insert is rigidly held in the body and ‘energized’ onto the spherically machined disc by means of the secondary seat which extends onto the disc periphery and is fixed into the body by a bolted in retaining seat. When the PTFE insert is burnt away, during a fire, the secondary metal seat is designed to ‘energize’ onto the disc and form a seal in both directions.