An A to Z Guide of Gate Valves for Water Applications
Gate valves are one of the most versatile valve choices among others as they are used widely for all types of applications. Crucial industries like different types of water system applications also have high demand for gate valves.
If you have ever wondered how a gate valve got its name is because of its closing element. It basically slides into the flow stream to deliver closing operation, hence, acting like the mechanism of a gate.
It is a linear motion valve that has been designed to start or shut water flow. Gate valves are intended to serve the purpose of isolation valves and are installed in pipelines to isolate specific areas of the system.
Today, in this blog we will be going through all the basics about gate valves and gain thorough knowledge about it. Read till the end of the blog to know all about gate valves for water applications.
Gate Valve Design and Its Components
Gate valves are known for having an overall simple design and fits well in several low pressure-drop services. Therefore, making the gate valves one of the most commonly used valves in the market.
In a fully open position, a gate valve operates with no obstruction in the flow path which results in extremely low pressure loss. This design supports the use of a pipe cleaning pig for gate valves.
Gate valves are multiturn system valves which means its operation is carried out by a threaded stem. Since the valves have to be turned multiple times for changing its position from open to close, this slow operation contributes to preventing water hammer effects.
Now coming to the components of the valve, here we dissect the anatomy of resilient seated gate valves with a non-rising spindle. The key parts of this type of gate valve are -
- wedge
- valve body
- seating area
- stem (spindle)
- spindle bearing
- bonnet
- packing
The disk of the valve is referred to as wedge. The gate valve consists of a body, which is the largest component. The spindle remains within the valve body during rotation, making it a cost-effective bonnet construction.
The valve bonnet is attached to the body using bolts, allowing for easy cleaning and maintenance. When the gate valve is closed, the wedge moves downward until it tightly presses against the valve seat, providing complete closure. During the opening, the wedge slides towards the upper part of the valve body.
Over the past century, the construction of wedge gate valves has undergone minimal changes. However, certain elements of the valve design have been modified.
These changes primarily focus on enhancing the valve's lifespan, improving its sealing properties, utilising high-quality materials, and applying epoxy coatings for superior corrosion protection.
Additionally, modern gate valve bodies are designed to be compact and streamlined, enabling installations in confined spaces. We at Dutco Tennant LLC are noted among the best resilient seated gate valves suppliers that offer quality products for diverse projects.
Different Types of Gate Valves Available
Depending on its construction, gate valves for water applications are generally categorised into the following types -
- By stem: with rising or non-rising stem
- By seat: metal seat or resilient seated gate valves
- By wedge: parallel gate valves and wedge gate valves
Types of Gate Valves As Per Stem
Rising Stem Gate Valve: In a rising stem gate valve, the stem rises and lowers with open and close positions respectively. The stem thread does not come in contact with the flow media which results in its corrosion-free performance.
Non-Rising Stem Gate Valve: In non-rising stem gate valves, the stem which is also referred to as an insider screw, is threaded into the gate. Unlike the rising stem gate valves, here the stem does not go in upward movement. The disk of the valve moves along the stem like a nut upon stem rotation. This design enables it to be an ideal choice in limited space systems.
Types of Gate Valves As Per Seat
Metal Seated Gate Valve: In gate valves with metal seating, a wedge moves towards a groove located in the lower part of the valve body. This groove has a tendency to capture solid particles that are present in the fluid.
Resilient Seated Gate Valve: Resilient seated gate valves employ a wedge, typically made from ductile iron material, that is enveloped in a resilient material, such as elastomer. This design ensures a secure seal. The sealing occurs between the edge of the wedge and the valve body, eliminating the need for a groove at the bottom of the valve. Consequently, resilient seated gate valves are capable of effectively sealing even when encountering small solid particles transported by the flowing water.
Types of Gate Valves As Per Wedge
Parallel Gate Valve: It is also known as Split Wedge Valve as it consists of two solid pieces (disks or wedges) accompanied by a specialised mechanism. The knife gate valves are a type of parallel gate valve. In this valve, the two discs are moved apart against parallel seats by a spring at the closure point.
Wedge Gate Valve: This type of valve gets its name from a wedge-shaped gate that it features. The wedge features ribs on both sides and is guided by the slots present in the body of the gate valve. In water distribution systems, this type of gate valve is primarily used.
Gate Valve Operation
Gate valves have similar operation like other valve types. They are usually operated by a handwheel, a wrench (valve T-key) or an actuator. To turn the gate valve into an open position, operators need to turn the handwheel causing the gate to move up or down on the stem through the threads.
For the operator to achieve a fully open or close position, the gate valves are required to be turned more than 360 degrees. When the gate rises up completely it opens the inlet to the outlet permitting an unobstructed passage of water to flow through the pipelines.
When the gate is lowered to the flow stream then it readily blocks the flow resulting in a closed position. In a gate valve, the connection between the vertical movement of the gate and the flow rate is non-linear, with the most significant changes happening when the valve is nearly closed.
When the valve is partially open and used to regulate flow, the relatively high velocity of the fluid can lead to wear on the gate and seat. This, coupled with potential gate vibrations, reduces the lifespan of the valve. Consequently, gate valves are best suited for binary on/off control rather than flow regulation.
If you want the best quality gate valves then be sure to check our stock where we offer UL FM approved gate valves.
Bottom Line
Gate valves are extremely flexible when it comes to their deployment in different system applications. Their usage has been seen in a wide variety of water applications, from wastewater to potable water systems.
In this blog, we have covered some of the key aspects of gate valves that can help you know more about this valve. We at Dutco Tennant LLC distribute a broad range of gate valves for potable water and other varied water applications.
If you are interested to know more about gate valves or want to explore our product range then be sure to visit our site now.