Choosing the optimal material of construction for a valve can be a consequential decision when designing fluid control systems. Some materials can handle corrosive chemicals while others are suitable for high temperatures. Some offer environmental advantages and others are cost effective. In advanced, complex applications, multiple factors are usually involved, so it is valuable to have a wide selection of materials.
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Metals have been used to make valves since the Romans fabricated bronze plug valves to use in their waterworks, if not earlier. Even today, the majority of valves continue to be made of some type of metal, with materials ranging from inexpensive die cast to aluminum, brass, stainless steel and finally high performance high-nickel alloys such as Hastelloy and Monel.
At the same time, modern plastics such as PEEK, PVC, PTFE and polypropylene play an increasingly important role in valve design. These materials can allow valves to perform in service conditions that would have been impossible a few decades ago, including many pharmaceutical, semiconductor and chemical processes that have impacted countless lives around the world. Plastic valves will no doubt continue to enable cutting edge innovation even as scientists and engineers deal with the environmental challenges that current polymers sometimes present.
Most commercial valves use polymers for their static and dynamic sealing, including the main closure seat. For static or sliding seal applications, polymers or elastomers (polymers with viscoelasticity) are often selected due to their ease of use, robustness to a wide range of tolerances and generally good leak tightness.
For the main valve seat closure, polymers are also robust to a wide range of tolerances and provide for Class VI or bubble-tight shut-off, which is adequate for most industrial and chemical applications.
While metal/metal seals and shut-off are considered to have the tightest sealing performance and are especially useful when working with high vacuum or small molecules like hydrogen or helium, they are more difficult to work with, requiring much more force and much tighter tolerances. As a result, metal/metal seals are usually used only where required.
Plastic bodies are not as widespread as polymer valve seats. They are usually specified for one of the distinct advantages they offer, including:
At the same time, these advantages must be weighed against potential disadvantages of plastic valve bodies. Depending on the specific polymer, these may include:
When an industrial process requires high pressure and/or extreme temperature together with excellent corrosion resistance, a polymer lined metal valve is often the solution.
Polytetrafluoroethylene (PTFE), perfluoro alkoxy (PFA), and polyvinylidene difluoride (PVDF) are high value fluorinated materials that resist aggressive chemicals, but they are structurally weak, soften with temperature and are too expensive to be used in large installations. These complex lined valves are typically cast from carbon steel and lined with intricate sleeves of fluorinated polymer and seals.
Not surprisingly, certain industries tend to value the advantages of plastic valves more than others. These include the following:
Chemical processes using all-polymer piping and fluid systems are the most common type of industrial application using plastic valves. For example, injection-molded trunnion ball valves are dominant in plastic piping systems. Such systems are selected for their low cost and excellent chemical resistance.
Many polymers are used in these systems, including:
Three single use polymer back pressure regulators provide transmembrane pressure control in a Single Pass Tangential Flow Filtration (TFF) biopharmaceutical application.
Source: Equilibar
The high cost and complexity of sanitizing valves and other fluid components has led to a large movement toward single use components and tubing in biopharmaceutical and medical applications. The ability for gamma and other high-energy radiation to penetrate polymer components, as well as the hygienic nature of injection molding, has caused valves made from certain polymers to be increasingly selected in these applications. Polymers should be selected considering gamma stability and typically include polyethylenes, polypropylenes and other materials capable of being rated as USP Class VI and ISO . Pressure ratings for these liquid valves are typically not greater than 60 psig, and they are often used below 10 psig, making these applications well suited for plastic valves.
Residential potable water systems frequently use polybutylene (PEX) or acetal (POM) valves to meet cost, purity,and reliability requirements. Residential drain systems frequently use PVC valves and piping in larger sizes for cost reasons.
A big user of high-value polymer valves is that of ultra-pure applications where metal ion contamination is a concern. Ultra-pure water (UPW) is surprisingly aggressive as a chemical. During the purification process, trace metal ions are removed. As a result, the UPW creates a high affinity to strip metal ions out of even high value stainless steel piping and valves. Therefore, the use of piping and components made of inert plastics such as PVDF, polyether ether ketone (PEEK), or olefin (polyethylene, polypropylene) is a requirement for maintaining ion-free liquids in a wide variety of semiconductor, photography and other sensitive processes.
Virtually all segments of modern manufacturing, including the valve industry, are grappling with increasing scientific evidence showing the harmful effects of accumulated PFAS and microplastics in water supplies and living organisms around the world.
As a recent article in this magazine explained in detail, the issue of forever chemicals — as these materials are known — is extremely complex. Fluorinated polymers like PTFE, PFA and PVDF have certain properties that our modern technology could scarcely survive without. In addition, these materials are key to green energy innovation such as hydrogen applications that promise to have a positive environmental impact. They are also key to the production of life-saving medications.
The challenge for valve engineers going forward will be to balance competing needs and use the most appropriate materials for each application. The mindful consideration of factors such as end-of-life recycling and disposal will become increasingly important, as will the adoption of emerging technology capable of destroying forever chemicals in the environment or otherwise mitigating their harmful effects.
Control is a powerful thing in life. Not just when it comes to the way we interact with each other, but also when it comes to the way we manage our environment. Valves are a great example of how humans use control to manipulate and shape their surroundings, whether that’s for practical or aesthetic purposes.
This article will explore irrigation valves and all there is to know about them before buying - from how they work, to the types of irrigation valves available, their uses and benefits.
Contact us to discuss your requirements of All-plastic Valve. Our experienced sales team can help you identify the options that best suit your needs.
A 'valve' is a device used to regulate the passage of liquid in a closed system from one place to another. It finds value in applications that require direct control over where things go and how - valves can offer functionalities like on-off control, flow rate control, pressure control, and backflow management. You might find these valves in plumbing, fire sprinkler systems, gas pipelines and industrial machinery.
When it comes to gardening and agriculture watering systems, 'Irrigation Valves' are responsible for controlling the flow of water into a garden (or other outdoor area) and the distribution of water into each sprinkler head. They are specifically designed to handle high-pressure applications and can regulate many aspects of water flow from the amount of water released to how quickly that water is released. Irrigation valves come in a variety of sizes and styles, but all serve the same basic purpose: controlling where and how much water is being delivered to an area at any given time.
Irrigation valves can differ from one another in many ways. You can't just go down to the department store and pick any option off the shelf - there are numerous types to understand and consider, some of which are better suited for certain use cases than others. To give you a better idea of what we're talking about, we've compiled this quick overview of the three most common types of irrigation valves below:
An angle valve is a type of plumbing valve that has two openings which are positioned at a 90-degree angle to each other. These valves are typically used when you need to control the flow of water or gas in a specific direction. Angle valves come in many different sizes and materials and can be used for a variety of applications.
Angle valves are especially useful when it comes to controlling the flow of water in plumbing fixtures, such as sinks or toilets. In the context of landscaping, angle valves are used to control the flow of water from sprinkler systems. Their top and side inlets work together to create a tight seal, ensuring that the desired direction of water flow is achieved.
Siphonage occurs when there is a difference in pressure between two points of a liquid-filled system. This causes the liquid to flow in one direction, creating a vacuum that can pull air and foreign materials into it. Irrigation systems in particular often face a high risk of backpedaling all sorts of unwanted elements into their pipes because they're constantly exposed to changing weather conditions and fluctuations in fluid levels.
Anti-siphon valves are designed to prevent this kind of problem from occurring. They are installed at the highest point of a line, usually near the water source or somewhere just above ground level. The valve includes an internal spring-loaded mechanism that shuts off automatically when it senses a change in water pressure. In addition to their primary purpose of preventing siphonage, anti-siphon valves also act as a failsafe against flooding and other damage caused by pressure fluctuations.
Ball valves consist of a cylindrical body that houses an internal ball with one or more ports. As the ball is rotated, it opens or closes off the ports, creating a seal that allows for flow control in one direction.
Ball valves are highly durable and are capable of withstanding high pressures, temperatures, and vibration, making them a common choice for homeowners installing new irrigation systems.
Angle valves, anti-siphon valves, and ball valves - simple enough, right? Well, before you spring forward and choose one for your property, there's one other big differentiator to know about. While the three aforementioned categories of valves manage water flow differently, two distinct control mechanisms dictate how these valves are opened and closed. Read below for a breakdown of each option in detail.
Manual irrigation valves, as the name implies, require human intervention to turn them on or off: you have to physically open it yourself with a key or lever. These are typically the cheapest option of the two, but can be time consuming if you're managing a large system.
Automatic irrigation valves open and close through electronic controls. This means you don't have to worry about manually operating them - the valves will open and close on their own based on predetermined settings. Automatic irrigation valves are typically more expensive than manual ones, but they're also much more efficient since they can be programmed to operate automatically and adjust water flow as needed.
Here's another thing you probably forgot to consider when starting your shopping journey - valve sizes. The industry has plenty of them, and again, what works for one situation likely won't work for another. It's important to pick a properly-sized valve, as one that's too large can lead to overflowing, while one that's too small can cause water pressure problems.
The best way to determine the proper size of valve for your irrigation system is to take into account the type and amount of water flow you need. The key measurements you'll need to consider are the water's pressure, flow rate, pipe diameter and head loss. These four pieces of data should help you determine the most appropriate size of valve for your system.
Generally speaking 3/4-inch valves work well for most residential properties where the water flow rate is around eight to 10 gallons per minute (GPM). Any applications with a flow rate exceeding 15 GPM should use a one-inch valve.
If all this sounds too complex or if you're still feeling unsure, then the best thing to do would be to consult a professional irrigation specialist who can help you pick out the right valve size for your system.
Now that you're familiar with the fundamentals, it's time to brush up on some good old buyers' best practices. Beyond things like configuration and size, you'll want to consider a few key factors to ensure you're purchasing a product that pays off in the long run.
A great way to gauge the reliability and performance of an irrigation valve is to research its brand. Many manufacturers have established reputations for high-quality products that stand up better over time, so it's worth doing your due diligence. Be sure to read customer reviews and see what other buyers have had to say about the product before you make your purchase.
No matter how much research you do, sometimes a product won't live up to its promises. That's why when purchasing an irrigation valve, you'll want to make sure that it is durable enough to stand up against the elements and last for a good amount of time. Look for corrosion-resistant materials and seals that can stand up to weather and temperature changes. Also, check for warranties that will cover any issues you may encounter down the line.
At the end of the day, your valve needs to get a job done. Prioritize valves that are energy efficient and have the capability to intuitively respond to various conditions. Models with smart controllers, sensors, and other features that can help you conserve water and save money on your utility bills over time are certainly worthwhile.
Overwhelmed by all of the options out there? Let us make the decision process easier for you by suggesting one of our best-selling products. The Rainbird 3/4" Plastic Anti-Siphon Irrigation Valve is designed for use on residential and commercial irrigation systems with a flow pressure between 0.2 and 22 GPM. Constructed with durable materials that can stand up to a range of temperatures and climates, this valve is reliable and easy to install. It also comes backed with a 100% Customer Satisfaction Guarantee for added peace of mind.
The best part about choosing this valve - or one of the many other options available through our online store - is that it's compatible with popular accessories and upgrades. Top Notch sprinkler valves are available in both manual and electric models, and can be adapted to include a timer for enhanced convenience.
Whether you're looking to replace a faulty valve or just need to upgrade your existing system, we've got the products and expertise to help get your irrigation system back up and running in no time. Start shopping today!
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