The valve is a bi-directional tight shut-off device incorporating a resilient seal mechanically retained around the periphery of the valve disc. The seal is available in various types of elastomers, the selection being dependent on the valve duty and working pressure and temperature. The seal seats against a metal face machined into the body of the valve. Positive shut-off is achieved without excessive interference between seat and seal ensuring maximum seal life and low seating and unseating torques.
The E-Series has an ebonite lining which is a hard, natural rubber, bonded and autoclave cured to achieve maximum strength and adhesion. It has a corner locking overlap feature around the flange and shaft bores to maintain optimum stability. The seat contact area, against which the resilient disc seal ring locates, is fully machined to ensure consistently tight shut-off.
In operation, there is a key difference when compared with other rubber lined valves. The ebonite is part of the structural rigidity of the body and the resilient seal is disc located. This is the element being compressed during sealing on closure. This eliminates dragging on the liner, which occurs on other valve designs where the disc is solid and the seal is made by compression of the liner. It is particularly effective in high-chlorine environments such as brackish water and seawater, where the natural resistance of Ebonite insulates the wetted portions of the valve body from corrosive attack by such aggressive media. The use of Ebonite in this application allows the use of Carbon Steel valve bodies, and actually makes them more corrosion-resistant than stainless-steel bodies in brackish water applications.