Knife Gate Valves (KGVs), began their journey in 1927 in the Swedish Pulp and Paper Industry. The knife gate valve was created because the market needed an affordable valve to be used in pulp stock applications. The world has seen many knife gate valve designs change over the years. The Push-Through Knife Gate was created in the United States, while the Guided Shear Gate is from Switzerland. Although we have accepted the term “knife gate” as a generic description for all versions of this valve, it may surprise you to learn that only the Guided Shear Gate and its higher caliber adaptation, the SSKGV, can actually “cut” through media like a knife. This article will explain, differentiate, and clarify each Knife Gate Valve’s capabilities and limitations.
A knife valve uses a blade to remove heavy liquid clogs. These anix valve usa are designed to work in the most corrosive and erosive environments.
Knife-type gate valves were initially designed for the pulp-and-paper industry. The wedge and seat of a standard gate valve would be blocked by stringy pulp, preventing flow shut-off. Knife gate valves are specially made with a sharp edge that cuts through pulp and seals.
Working of Knife Valve
This highly efficient design makes knife gate valves an invaluable tool for applications that use viscous fluids or slurry, and where impingement is a concern.
These valves are widely used in many processing plants. They come in large sizes that make it easier to handle heavy greases, heavy oils, varnishes, slurry, and wastewater. These valves have low-pressure limitations and are designed for the blade to be seated into an elastomer seal after it has cut through the substance being handled. These soft seals allow thick liquids to glide easily over them. However, when a powder or solid material passes through the knife gate it will pack into the soft seals at the end. The seals will eventually stop closing tightly enough when this happens. This is a sign that the seals need to be replaced.
Why not use Knife Gate Valves
These valves should not be used to regulate flow. Fluid is forced against partially closed gates by vibrations, which gradually wear away the seat and disk. Knife gate valves should not be opened or closed completely. These valves can also be opened and closed slowly to protect against water hammer impacts.
Knife Gate Valve vs. a Gate Valve
The main difference between knife gate valves versus gate values is that knife gate valves conform to TAPPI standards, while gate valves are manufactured according to ANSI standards. Gate valves are also flanged and wider dimensionally. They must be ANSI pressure rated, meet API leak tightness standards, and have to be ANSI pressure rated. They are used widely in fluid applications and have bi-directional gate values. They only come with metal seats. The packing gland area is another difference between a knife and ANSI gate valves. The shaft of a gate valve is sealed by a v ring packing set. Knife gate valves feature a packing gland that seals around them.
An ANSI gate valve is more narrow than a knife gate valve. Knife valves are primarily unidirectional, although some options can be bi-directional. They have a lugged body or wafer body without flanges. You can find knife gate valve seats in a variety of materials, from metal to resilient.
The two most important benefits of knife gate valve manufacturers include their weight (16″, usually less than 300 lbs) and cost. ANSI gate valves weigh more than 1200 lb and are therefore more expensive.
