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!
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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.
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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.
Part One: Choosing the Right Fluid Dispensing Valve System
Is your current dispense valve system giving you accurate deposits with minimal maintenance &#; or are you applying inconsistent amounts of fluid and wasting too much time and money on downtime, rework, and cleanup?
This blog series discusses common problems encountered with typical dispense valve systems by asking some of the most common questions. It also offers helpful tips for improving valve performance. This first part in the blog series answers the top two questions we have encountered most frequently. We hope that you find this information helpful.
1. Are You Using the Best Dispense Valve for Your Fluid Application?
In most situations, best results will be obtained with a valve style and configuration carefully matched to the specific properties of the fluid being dispensed.
Thick Fluids
Thick materials like RTV silicone or heavy grease, for example, pose very different challenges than thinner fluids like adhesives or threadlockers. When using thick fluids, a high-pressure valve with a balanced spool design will provide good control. Also, look for a snuff back feature as it will prevent drooling and tailing and help reduce the rework and cleanup often associated with these more challenging assembly materials.
Thin to Medium-Viscosity Fluids
Thin fluids like solvents and watery adhesives have much different requirements, especially when very small deposits are needed. For these applications, needle valves are often recommended because shutoff occurs close to the valve outlet or dispense tip. This is an important design feature because it minimizes dead volume that can cause dripping or oozing. For critical applications, there is even a needle valve that seats the needle in the dispense tip instead of the valve body. By virtually eliminating dead volume, this design makes it possible to produce even smaller and more consistent micro-deposits.
Learn more about how to choose the right valve by downloading our Dispense Valve Selection Guide.
Tricky Fluids Like Cyanoacrylates (CAs)
Wetted internal parts, as well as any fittings and tubing that come in contact with the fluid, should always be carefully chosen for compatibility with the fluid being dispensed. When working with cyanoacrylates, for example, wetted parts made of inert Ultra High Molecular Weight (UHMW) polymers are a good choice because they will not react with the fluid. Nylon or metal fluid fittings, however, should never be used with CAs because they absorb moisture and will promote premature curing. Use polyethylene or polypropylene fittings instead. Chemically inert, polyethylene-lined or PTFE FEP tubing are good choices for fluid feed lines.
Learn more about the right setup and maintenance for cyanoacrylate dispensing by downloading our Cyanoacrylate Dispensing Guide.
2. Are You Using a Dispense Valve System &#; or Just a Dispense Valve?
Taking a &#;system&#; approach to fluid dispensing and carefully evaluating all the details &#; even something as small as a fluid fitting &#; will help prevent many problems on your assembly line. A dispense valve system has four main components:
- The dispense valve
- A means of initiating the dispensing cycle
- A precision dispense tip
- A fluid reservoir
The greatest accuracy, reliability, and production yields will be obtained when all four components are engineered to work together as an integrated system. This approach will also simplify qualification and validation processes. Optimum PTFE-lined tips work best with low-viscosity cyanos. They feature a special lining that prevents curing and clogging.
A valve paired with a dedicated valve controller will typically provide faster response time than a valve triggered by mechanical means or a remote PLC. A dedicated controller will also allow deposit size to be fine-tuned with much greater precision than other methods and can be interfaced with the assembly line&#;s main PLC.
Precision dispense tips should be of high-quality materials to ensure unobstructed fluid flow and matched to the specific fluid and volume being dispensed. Fluid tanks should always be fitted with constant bleed regulators to maintain steady fluid pressure and prevent variations in deposit size as the fluid level moves from full to empty.
In the middle of coping with day-to-day production challenges, it can be difficult to calculate just how much poor valve performance is really costing you. However, doing so could save you money, increase production, reduce bottlenecks, and improve the overall quality of your products.
Next Up&#;Part Two: Troubleshooting Your Dispense Valves
In the next part of our series, we&#;ll look at how to set up your valve system for optimal performance by providing answers to some troubleshooting questions.
Have a question about how to choose the right dispense valve system to begin with? Don&#;t hesitate to us at .
About Vlad Konopelko
Vlad Konopelko is a Global Product Line Manager at Nordson EFD. He manages the dispense valve product line. Vlad has more than 16 years of product management experience in various sectors, including electronics. He joined Nordson EFD in .
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