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Powder Handling in Silos.
Uni-directional knife gate valves are widely used in this application. The valves are mounted horizontally below silos. Typically the orientation is such that the seat faces downwards as in this case there is less chance of the media settling on the seat area and possibly obstructing the valve closure. One point to be noted while selecting valves is that knife gate valves cannot close against a stagnant column of packed powder material. The powder material must be flowing while the valve is closing.
Pulp & Paper plants
With its ability to cut through pulp and paper stock, knife gate valves are the valves of choice in a wide range of applications in pulp and paper plants. Besides on/off applications, this industry also uses v-orifice knife gate valves for throttling and control applications in pulp stock. Pulp containing waste material such as those occurring in reject pulp (recycled paper) plants can be handled by the FIG 780 O-port valves.
Slurry handling
Knife gate valves are widely used in handling all types of slurries in mining, thermal power plants, chemical processing and other industries. Depending on the location where the valves are to be used they could be of the uni-directional or bi-directional design. Special constructions such as purges and accessories like deflection cones are usually used in these applications to improve the life of the valves.
Water & Sewage applications
This is an industry which traditionally uses knife gate valves. Both metal and soft seated uni-directional valves and bi-directional valves are widely used. Generally the sizes involved are large; valves with both cast iron and stainless steel body are common. Actuated valves tend to be electrically operated; many of the large valves that are manually operated are with extensions and floorstands as well.
Pneumatic Conveying Systems
Knife gate valves are widely used in pneumatic conveying systems as they offer a large flow capacity with minimum pressure drop as well as ability to close with powder material in the media. Valves used in such applications are usually actuated-pneumatically or electrically as the operation sequences are automated. Typical applications that utilize knife gate valves are systems conveying cement, polyester chips, flyash, grains etc.
High temperature services Uni-directional knife gate valves with suitable packing and materials of construction are widely used to handle high temperature contaminated media. The simple design of the valve, with the gate held in place by a set of packing, allows it to handle temperature fluctuations (and consequent expansion/contractions and resultant warping) much better than most other valves designs. In view of this advantage, knife gate valves are widely used in carbon blank plants handling dirty gases at over 550 deg C as also as boiler bed ash valves where with suitable metallurgy, they handle media around 800 deg C
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Industrial Application