Knife gates are devices that serve as shut-off devices in pipelines. They are widely used in utility facilities of water supply, sewerage and heating, in energy facilities for the production of steam, hot water and compressed air, in shipbuilding, metallurgy, chemical and petrochemical industry and other branches of economic activity.
The use of valves is especially recommended in pipelines in which they are completely open or completely closed during operation, and the flow of working fluid can be in both directions.
Interruption of the flow occurs due to the lowering of the shut-off discs into the valve body normally in the direction of the flow of the working fluid. The shut-off discs are raised or lowered by the trapezoidal threaded shaft. The sealing surfaces on the housing and the disc are made with a slight slope so that this way of sealing reduces friction.
The sealing surfaces of the knife gate housing and the disc are made of stainless steel with a corresponding difference in the hardness of the surfaces. This avoids the undesirable shear of the material due to friction. Sealing between the output part of the shaft and the upper part of the housing is done by a graphite braid. For clean and non-aggressive working fluids we use valves with axial-fixed spindles, and for dirty and aggressive working fluids we install valves with movable spindles. For liquids with a high content of thick dirt or sand, we supply valves with a sludge channel.
Gate valves are made with installation lengths that correspond to the standard SRPS M.C5.005 – F4 and DIN 3202 – F4, connection dimensions of flanges are designed according to SRPS M.B6.011 and DIN 2501, maximum nominal diameter DN 2000 (mm), maximum nominal pressure NP 10 (bar) and temperature 200 (° C). The drives that we deliver with gate valves are manual and/or electro-mechanical, and at the request of customers, we also supply gate valves with other types of drives.
The housing and shut-off discs of gate valves are made of structural steel, with the sealing surfaces on them being made of stainless steel of appropriate hardness. The trapezoidal spindle is made of appropriate stainless steel, and the plain bearings are made of grey cast iron.
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