Know More. Grow More.
You will get efficient and thoughtful service from Huade Hydraulic.
By
Matt Clift
(Director of Global Product Management & Marketing)
In terms of variety of product options to choose from, hydraulic valves have some of the widest array of options to choose from. There are quite literally hundreds of different configurations possible!
However, it doesn't need to be complex. In this article of our Know More, Grow More series, we will simplify the process and will present the two primary questions you need to ask when selecting a hydraulic valve.
As a reminder, for more information about selecting the right valve, or in fact any product in your drip irrigation system, make sure you check out Module 2 of Rivulis Knowledge Hub.
Selecting the right valve type may seem complex, but it becomes straightforward by answering two key questions:
- What is the valve's primary function?
- How will the valve be operated or controlled?
Question 1: What is the Primary Function of the Valve?
The first question focuses on the primary function, or "what the valve does." There are nine different primary functions for hydraulic valve as follows:
- Basic: A valve body without any accessories, often used by growers and dealers who wish to build their own valves.
- On/Off: This valve is either on or off, with no pressure regulation or flow control since there is no pilot. Ideal for simple in-field operation and small farms without automation.
- Pressure Reducing (PR): Reduces downstream pressure for consistent water pressure, and subsequent uniformity in each block regardless of upstream pressure fluctuations. The majority of valves are PR valves in most irrigation systems.
- Pressure Sustaining (PS): Maintains upstream pressure, important for components such as filters that require a minimum pressure for back-flush.
- Pressure Reducing & Pressure Sustaining (PR/PS): Combines both functions, eliminating the need for two separate valves.
- Electric Control: Controls valve opening through electric automation, allowing remote operation.
- Quick Relief: Acts as a safety valve by relieving system pressure above a preset value. Unlike PR valves, quick relief valves are for quickly expelling excess pressure when spikes occur.
- Flow Control: Restricts flow to a determined rate. These are different to PR valves as the valves restrict to a specific flow through differential pressure. An example of use is to restrict the flow of back-flush discharge from a media filter during flushing.
- Level Control: Opens and closes valves based on set tank points, useful for maintaining storage water levels.
Question 2: How Will the Valve be Controlled?
We now know what the valve will do. The second question addresses how the valve will be operated. There are three main options:
- Manual: Involves a ball valve for manual operation. Often remotely controlled valves will have a manual override added to the valve in addition.
- Hydraulic: Utilizes water pressure transferred through a hydraulic tube to control the valve's diaphragm via a hydraulic relay.
- Electric: Uses a solenoid where current through a wire creates a magnetic field that moves the piston.
By answering two questions above, you streamline the process of selecting the right hydraulic valve for your system.
Next Steps
Once you have determined the primary function and control method of your valve, the next steps involve specifying the valve's parameters and accessories:
Contact us to discuss your requirements of solenoid operated directional control valve. Our experienced sales team can help you identify the options that best suit your needs.
- Material: Choose between plastic or metal based on your application. Plastic valves are lighter, more economical, and corrosion-resistant. Metal valves are necessary for higher pressure and larger size applications.
- Size: Choose the size based on the required flow and head loss. This is chosen according to the needs of your system's hydraulic design.
- Connection Type: Select the connection type according to your region (standard for your country) and application need (flange, thread, etc).
- Pilots: Are chosen to the pressure regulating requirement of the hydraulic design and the system components.
- Throttling: Controls how much a valve can open. It does not regulate pressure, i.e. it does not respond to pressure variations. It only puts a limit on how much the valve can open.
- Solenoids: Are available in a wide range of variations, and your selection will depend upon your control system and valve application.
Dive deeper about hydraulic valve selection in the Valves Section on the Rivulis Knowledge Hub, or download Book 2 for the complete guide for drip irrigation component product selection.
Read more about Rivulis's hydraulic valve product offering in the valve section on rivulis.com.
Please note. This article is provided as a high level overview only. It is important that you verify what is best for your specific application, including for design, installation, operation, and maintenance. For both personal and irrigation system protection and before use, it is important to read the relevant suppliers' instructions (for non-Rivulis products such as pumps, chemicals, fertilizers, etc), to consult with applicable professionals, and to read the relevant section of the Rivulis Drip Guide/Knowledge Hub, particularly with respect to safety and handling information, and more detailed instructions for use.
Automatic control valves, much like everything else we purchase these days, are not all created equal. Some fall into the high quality bracket with pricing to match, while others hover closer to the lower quality and price sensitive end of the scale. Unfortunately, when evaluating control valve prices, it is not always clear what you are being offered and what standards the valve actually meets. Here are a few questions to consider and ask the supplier to ensure you get years of trouble free operation that lasts longer than it takes the sales person to drive out of your parking lot!
Q 1 What materials are being used?
Make sure you know what the different components of the valve are made of, as this will certainly affect the life of your valve, specifically:
Body Material ' is the valve body cast iron or ductile iron? Traditionally valves were cast iron but ductile iron has become the new standard due to its superior physical properties that are much better at weathering the elements.
Body Coating ' Most of the world insists on fusion bonded coating of a valve, inside and out. Unfortunately here in North America, that is not always requested. This just makes common sense for valves that are constantly wet and sit in locations that are not always dry and pristine. A valve should last for many years, so insisting on a coated valve is a wise choice.
Seat Material ' bronze is typically the common material for seats but over time, depending on water quality and velocities, bronze wears resulting in the need for replacement. This is time consuming and expensive as seat replacement requires a complete disassembly of the entire valve. Ideally go for stainless steel.
Valve Internals ' Most valve manufacturers utilize stainless steel for their valve stems. Make sure that you ask what grade of stainless you are getting as not all stainless steel is created equal. 316 SS is always the best choice because it is harder and least likely to corrode.
External Fasteners ' Over time valves experience condensation or flooding and this can play havoc with coated studs or bolts. There is nothing worse than trying to remove heavily rusted studs out of an old valve to perform maintenance. Request stainless steel fasteners as this will ensure that bolts will be removable at any age.
Q 2 Does the valve supplier fully understand your application?
Too frequently a specification will be requested and a valve is supplied that is simply the wrong valve for the job. It may also be the case that there is just a better solution. Ensure you give your valve supplier all the necessary pressure and flow details including details of the actual application and what you want this valve to do. Having the wrong valve for the wrong application, at best case will result in a significantly shorter life and worst case, a malfunction that can result in destruction of the valve and other parts of your water distribution system.
Q 3 Will this new valve fit into my existing piping layout?
Don't be tempted to just stay with brand X because that is the valve you may be replacing and has the same lay lengths. Most manufactures can be quite innovative on providing solutions to combat varying lay lengths so explore all of you options rather than just settling because you think it may be easier.
Q 4 Do you need specialty tools for maintenance?
Nobody wants to have to carry around a specific tool that only performs one task. Ensure that your valve can be maintained with everything you would carry in regular tool kit. Some valve manufacturers require specialized seat removal tools, or vice jaws installed with copper jaws to protect valve stems. While these are great ideas, they are certainly not things that the average operator has in his toolkit.
Q 5 Will your personnel receive complimentary factory qualified training?
Control valves are not so difficult to understand and once taught, most operations personnel can easily perform maintenance. Ensure that you will not be reliant on the additional cost of having to bring out a factory person every time your valve requires maintenance. Request that a factory-trained representative is on site when the valve is commissioned. This will allow your operators to be schooled in the regular maintenance needs, know what to look for if things go awry and how to start up a valve in a new system or after service. Simple tricks like removing air out of the pilot system are valuable lessons to see in practice.
Q 6 Does your valve have a solid warranty?
These days having a product with the long term back up of the factory is important. Three years should be the standard to ensure there are no manufacturing faults.
Q 7 Can I make changes to the valve if required
Having a valve 'expansion ready' for the future can save you money and make your decisions a whole lot easier. For example, can you add a limit switch or a position indicator easily? Or, if you need to move the pilot system to the other side of the valve, can you do it, or is it not possible because the valve body does not have the required connections? Things always change and a flexible valve gives you more options to keep your now perfect valve, perfect down the road.
Q 8 Does your valve meet industry standards?
There are third party accreditations that ensure your valve was built to the correct specifications. For example; NSF 61, WRAS, UL/FM, AWWA, ISO et.al. They are important because they ensure that the valve has been built to a given standard so the user can be assured they meet approval for such things as low lead content, bacterial growth tests, functional tests etc.
Q 9 Do you have local and factory support?
Make sure there is someone in the area that is factory trained and available to come out and assist when you have questions or problems. This sounds like a given but it's best to ensure the local agent will in fact be there for you when you need him. When a valve fails, timing is usually of the essence so you should know whom to call prior to such an event.
Q 10 Is the valve solution offered able to handle future needs?
In the world of 'low bid wins', a supplier may be tempted to squeeze as small a valve as possible into the application in order to reduce price. Make sure that the offered solution will supply your needs for the foreseeable future without the burden and additional cost of having to change a valve in a couple of years.
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