For applications requiring enhanced environmental and safety protection, the 9100 series is available as dual seals capable of working in either an unpressurized buffer environment or a pressurized barrier fluid system.
The Thomson 9000 series pusher seals are all stationary flexible elements as standard.
“Perpendicularity of the mating ring to the shaft axis is important for both stationary and rotating flexible element designs. “
“Perpendicularity for a rotating mating ring mounted on the sleeve (where a stationary flexible element is used) is controlled by the seal sleeve run out and perpendicularity of support surface on the sleeve. It is independent of the seal chamber face run out. An advantage of a stationary flexible element is that it will deflect to a fixed position to align with the rotating face. “
This fundamentally means that whilst the current standard views rotating and flexible element seals as the same. A design using a flexible stationary element has some benefits over flexible rotary designs that can not be dismissed.
Seals using a stationary flexible element with springs external to the process liquid are also a proven design in process fluids with high particulate concentrations.
Stationary flexible elements are preferred in many oil and gas applications such as:
It is important to note that the advantages of the flexible stationary face would apply even in applications that are not as demanding as those noted above. Flexible stationary faces should be considered the preferred option in almost all applications.