New soft-seated knife gate valve
From September 2007, KSB Aktiengesellschaft, Frankenthal, Germany, will add a soft-seated knife gate valve in cast iron to their extensive valve range.
Hera BD knife gate valves with bi-directional seal are available from DN 50 to DN 1200. Depending on their nominal diameters, Hera BD can be used at operating pressures of up to 10 bar. They are mainly designed for applications with solids-laden fluids, such as the treatment of waste water, sludge and storm water. Further applications are in the sugar, food & beverage and steel industries as well as in biogas plants.
The single piece body (up to DN 500) or two piece body (from DN 600) provides an unrestricted flow passage and is completely machined inside. This leads to very good flow characteristics and a perfect fit of components. The valve discs are made of stainless steel, polished on both sides. They are guided by a confined U-shaped rod seal for the entire valve travel. This means the valve is provides tight shut-off - no matter which direction the fluid comes from. The seal also prevents the disc from "fluttering" in intermediate position. Another feature of the body are its flushing corners, which enable flushing of the seat during valve closure.
The gland packing made of PTFE impregnated fibre tightly seals the valve to the atmosphere. It is easy to service by repacking the gland without having to remove the valve from the piping. A robust and compact mounting yoke made of steel facilitates the mounting of electric or pneumatic actuators and limit switches. The yoke as well as all other cast iron and steel components are protected against corrosion by an epoxy coating. The flange is connected via threaded pocket holes and bolts along the sides of the body, which means the gate valve can be used at full operating pressure as either a dead-end valve or a wafer type valve.
No further sealing is required as O-rings are integrated into the flange faces as a standard. Hera BD knife gate valves comply with the requirements of the European Pressure Equipment Directive. They also qualify for use in potentially explosive atmospheres of group II, category 2 to ATEX 94/9/EC.