Gate valves come in various shapes and sizes, and it isn’t always clear which one you’ll need to
buy. To determine the type of gate valve you need for your business’ special requirements, you
need to understand what a gate valve is, how they work and which types work best for which
Here, we’ve written a comprehensive guide to gate valves, which we hope will answer your
questions and help you come to an informed decision about which type of gate valve your flow
What Is A Gate Valve?
Gate valves are a type of valve that shuts off the flow of material. Gate valves are also
sometimes known as slide gates or knife gates. Gate valves can be turned on or off to prevent
material from moving or keep it in place.
Gate valves are used with both pneumatic and gravity flow systems. Knife gates have a cast
round body, while slide gates are fabricated with either round, square or even rectangular
flanges; and can be customized to clients’ exact needs. Because of this customizability, gate
valves can work with a wide variety of individual systems.
How Do Gate Valves Work?
Gate valves stop the flow of material or allow the free flow material. To stop flow, they place a
gate in the product flow, disallowing it from going past the designated point. The gate can also
be partially open/close to restrict or minimize flow as a crude device to control flowrate.
The gate on the valve can be open or closed; an open gate allows for easy flow, with no
resistance, while a closed gate restricts the flow of substances entirely. Gate valves work by
being connected to an actuator, which facilitates the use of the valve. Actuator types vary, but
typically a pneumatic air cylinder or a manual crank is used.
Types Of Gate Valves
Different types of materials require different constructions of valves. Both fabricated slide gate
valves and knife gate valves are readily available; while both are useful, each has specific
benefits and may work better for some industries than others.
Slide Gate Valve
Slide gate valves work best with solid materials and little or no air pressure in the system. As
their name implies, they work by blocking the material from moving with a sliding gate
mechanism. The sliding gate moves aside to either hold the material in place or allow it to flow freely. Slide gate valves work in gravity flow applications, allowing for easy flow for a wide
variety of materials.
Quality fabricated slide gate valves are mild steel or stainless steel with a robust design.
Because slide gate valves can be fabricated, businesses can buy them in any size or shape
they wish to fit their specific needs. Slide gate valves can be used for a number of purposes,
and can be used to transport food, granular materials, plastics and chemicals.
Knife Gate Valve
Unlike fabricated slide gates, knife gate valves feature a cast body with a rubber seat. These
gates are available with round flanges only. Their more heavy-duty design and rubber seat
allow them to seal against higher pressures and are better suited for more difficult applications.
The slide plate is sealed from atmosphere by a stuffing box with multiple rows of packing and a
gland follower. Pneumatic knife gates also feature an oversized air cylinder with optional reed
switches to indicate open/closed position.
Knife gate valves can be used for numerous industries, including but not limited to: the food
industry, animal feed, energy, mining and minerals, plastics and chemicals.
While slide gate valves only work with gravity flow applications, knife gate valves work with
pneumatic flow systems, too, making them a highly versatile option. They can be actuated by an
air cylinder or manual hand crank, similar to slide gate valves.
What Gate Valve Should You Choose?
Each business and industry has unique requirements and may be handling materials that differ
from other industries, so it doesn’t always seem easy to find the best gate valve for your
company. We hope that our guide will help you better understand the types of gate valves and
which best work with which types of materials.
Here at Carolina Conveying, we offer both slide gate valves and knife gate valves to fit your
company’s specific needs. Call today for a free consultation to determine what type of gate
valve is best for you, and we’ll be happy to help you every step of the way.