The 18-FR is a remote sensing, high capacity, spring and diaphragm operated, normally closed valve. The inner valve is held closed by the spring. When the sensed pressure increases above the spring setting, the valve opens.
The normally closed valve shall be of stainless steel construction with a spring to adjust the opening pressure.
The inner valve shall be of stainless steel 316 construction and the inner valve shall have EPDM resilient compound for seating.
A separate port will sense pressure to open the valve when system pressure exceeds the valve set-point.