So you need to spec a valve. Now what?
You will get efficient and thoughtful service from Afbv Valve.
The first step is to consider a few essential elements. What’s the purpose of the valve? What features do you need to include? Will it need to be serviced over time? How do you connect it to the system, including pipes and wires? What size should it be? When it comes to valves, there’s much to learn. For every project you take on, the key is to design with valves in mind. Read on for a primer on valve fundamentals and selecting the correct valve.
Valves: What You Need to Know
Valves are everywhere! We have valves in our hearts, in our engines, and in our showers. Put simply, a valve is a device that controls the flow through a passageway. In irrigation systems, you may see check valves, air relief valves, flush valves, master valves, isolation valves, remote control valves, and more. A valve can be described by:
Remote Control Valves
Now that you know what valves do and what they’re made of, let’s zero in on remote control valves (RCVs). These are automatic valves that control the flow of pressurized water from a mainline into a lateral line. They often correlate to zones in your design or stations in the controller. Depending on your local codes and conventions, consider an anti-siphon valve, an inline globe or angle valve, or an index valve. Inline globe valves are the most common, especially in commercial projects where backflow is already provided at the point of connection. These devices are inline with the pipe. The water enters one side of the valve and exits through the opposite side.
Linking the Hydraulics
To function properly, a remote control valve needs to be connected to the pipe and the electrical control system, then sized properly for the demands of the system. A variety of pipes exist, but the most common are polyvinyl chloride (PVC) and high-density polyethylene (HDPE or PE) pipe. The size of the valve, measured in inches or millimeters, correlates to the size of the pipe connection. PVC systems will use a slip or threaded valve connection. The most common thread type in the U.S. is National Pipe Thread (NPT). In international markets, British Standard Pipe (BSP) is often used. It’s important to note that the two are not interchangeable. HDPE or PE systems will use a compression fitting or an adapter. Once the hydraulic side of the valve is linked, connecting the solenoid to the electrical control system is simple.
Connecting the Electrical Components
There are two basic types of solenoids: AC and DC. Use an AC solenoid when powering with 24 VAC from the controller. Use DC-latching solenoids when powering with battery- or solar-powered controllers. If you have a two-wire system, connect the solenoid to the decoder according to the manufacturer’s instructions.
Sizing the System
Sizing the valve for system demands means ensuring your valve is suited to the quality, pressure, and volume of the water supplied. If the system uses reclaimed water, opt for a valve with a more robust diaphragm and internal filters designed for this water type. If a system must withstand extremely high pressures, address this with a pressure regulator at the point of connection and a valve suited to the final operating pressure of the system. Check manufacturer specifications for the pressure rating of the specific valve. It will vary by material, manufacturer, and model. Additional pressure regulation at the valve can help provide proper pressure to the system downstream of the valve.
Valve size is based on the water volume required to supply a zone. Manufacturers provide pressure loss charts for valves based on flow rate and valve size. For proper operation of the diaphragm and components inside the valve, there must be a small amount of pressure loss, but not so much that it strains the mechanism. The desired pressure loss in an RCV ranges from 2 to 5 PSI (0.14 to 0.34 bar; 14 to 34 kPa). Valve size is never based on the size of the mainline or lateral line pipe alone. It should always be sized for the flow demands of the zone. Here’s an example: If a 2" (5 cm) mainline is supplying a 1" (2.5 cm) lateral line, but the flow demand on the 1" (2.5 cm) valve results in a 9 PSI (0.62 bar; 62 kPa) pressure loss, then upsizing the valve can reduce this loss. Conversely, if a 2" (5 cm) mainline supplying a 1" (2.5 cm) lateral is given a 2" (5 cm) valve with a 0.5 PSI (0.03 bar; 3 kPa) pressure loss, the valve is oversized and should be smaller to accommodate the zone and save on material costs.
Selecting the Valve
Irrigation design novices often think the valve is the component that decides the rest of the design. They want to know how many spray heads they can put on a valve. The truth is they’re approaching the design in the wrong order. The valve is usually the last component to be selected. You must understand the supply type and system demands before valve selection occurs. Valves are complex. Taking the time to understand the function and features of each type will help you select the proper product for your design. Be sure to consider the manufacturer’s specifications, project requirements, and zon characteristics. It also helps to know the constraints of valve operations as this will help inform the design on the front end. When you design with valves in mind, it makes selecting the right valve much easier.
Globe valves appear in all aspects of society, but there are many types of them. We can divide different globe valves according to many conditions.
The Body Design
Globe valves can be roughly divided into three categories according to the valve body design: T, Y, Angle globe valve.
Actuated Globe Valves
1.Manual Globe Valve
As its name, this valve is opened or closed manually. It is generally installed with a handle or a handwheel. Large valves are fitted with turbines. Choosing it is the premise of the safe working environment, and the manual shut-off valve is also an economical choice.
2.Pneumatic Globe Valve
The Pneumatic globe valve, also known as “cut gate”, is one of the most widely used valves. The popularity is owed to it’s reliable sealing, small opening and closing torque, and easy operation. However, with large fluid resistance, pneumatic globe valve require large force to open and close; it is not suitable for media with particles, being high viscosity, easy coking and poor adjustment performance (because of the balance hole in the valve body); Large size and other shortcomings, so its scope of use has been limited.
3.Electric Globe Valve
The electric globe valve consists of an electric actuator, or a pneumatic actuator and a globe valve. Its closing part is a valve body, and the valve body rotates around the center line of the valve body to achieve opening and closing. It is simple in structure, good in sealing and easy to maintenance. The most important thing is that it is easy to operate, and there is no need to manually operate at close range.
4.Hydraulic Globe Valve
Hydraulic globe valves are mainly used to control the flow and cut-off of oil in hydraulic system pipelines and integrated oil circuits. The valve core is hydraulically balanced, with small opening force and reliable sealing performance.
If you want to learn more, please visit our website Thread Type Globe Valve.
Globe Valve Disk Types
1.Composition Disk
The composition disc uses a hard, nonmetallic insert ring design to create a tighter closure. For high temperature and pressure applications, composition disks are used due to the sufficient resilience and erosion resistance.
2.Ball Disk
The seat and disc construction is made of a ball-shaped metal disc. This possesses a short taper and it easily fits against a flat-surfaced seat in the body. Even though the ball disc is capable of throttling flow, it is primarily used to start and stop the flow.
3.Plug Disk
The plug disc is the best among all three globe valve disk designs, which is suitable for throttling services. A long tapered metal plug is made into a plug disc that seats into a cone generating a wide seating surface.
Location of Threads on Stem
The thread of the globe valve stem is on the outside of the valve body. In addition, the valve stem is not eroded by the medium and is easy to lubricate. This structure is relatively common.
Lower Threaded Stem Vlobe Valve
The thread of the globe valve stem is in the valve body. The stem thread of this structure is directly contact with the medium, which is easily corroded and cannot be lubricated. This structure is used in places with small diameters and low temperatures.
Connection
1.Screwed
This is the simplest design available, and it is usually used for inexpensive valves.
2.Bolted
This is the most popular design and is used in a large number of globe valves. This requires a gasket to seal the joint between the body and the bonnet.
3.Welded
This is a popular design where disassembly is not required. They are lighter than bolted-bonnet counterparts.
4. Pressure-Seal
This type is used extensively in high-pressure, high-temperature applications. The higher the body cavity pressure, the greater the force on the gasket in a pressure-seal valve.
5.Flange
Flanged globe valves are mandatory sealing valves. The force required to open and close is large, and the adjustment of performance is also poor. But it has a long life, and is also easy to maintain.
Sealed Form
1.Bellows Sealed Globe Valve
The sealing of the bellows sealing structure is quite reliable, and it is mainly used in flammable, toxic and corrosive pipelines.
2.Packing Seal Globe Valve
The packing sealing structure also has good sealing performance, and it is convenient to manufacture. What’s more, with low cost, and it is widely used in valves.
The company is the world’s best Flange Type ANSI Globe Valve supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.