Knife gate valves are primarily designed for on-off and isolation services in systems having a high content of suspended solids. Knife gate valves offer various benefits for handling slurry, viscous, corrosive and abrasive media. The valves have decreased pressure drop in a fully open position, are easy to actuate, have a relatively low weight and are cost-effective.
The name comes from its sharp, knife-like disc, which could be used for cutting medium. The groove around the seat permits the gate to push particles aside and prevents clogging. When the valve remains in an open position, the flow cleans the groove. The seat remains outside the flow area which results in a higher flow coefficient with minimum pressure drop.
Knife gate valves are designed to work in some of the harshest environments, typically having a sharpened blade to cut through heavy liquids. These valves are mainly designed for use in wastewater applications where corrosion is an important issue. With the addition to the valve design optimized for slurry media, having a knife made of acid-proof stainless steel is beneficial as this makes it less susceptible to damages caused by corrosion and as a consequence, it needs less frequent maintenance or even replacement.
We offer knife gate valves that do not have a bonnet and are available in both non-rising and rising stem variants with cast solid body, follower and yoke. These valves are resilient seating with wire reinforced rubber seat that is located below the bore and out of the flow line (full bore). This is capable of tight shut-off in both directions (bi-directional) and simple in-line seat replacement. The gate is prevented from being over tightened by the lock nut and the O-ring is provided between the layers of packing to sweep the sludge from the gate. The full flow and Bi-directional flow ensures that the knife valve maintains the highest efficiency and reliability.
It is ideal to use knife gate valves only for applications requiring a completely open or completely closed position and should not be used to regulate flow unless they are designed for it. There will be a vibration whenever any fluid is forced against a partially closed gate which will gradually erode the disc and seat. For safeguarding against water hammer, knife valves are designed to slowly open and close. They are preferably used in pipelines of pulp and paper mills, mineral processing & tailing systems of the mining industry, water & sewage processing for utilities and industries, ash processing of power stations and many other applications.