Top 10 questions you should ask when purchasing a ...

Author: Geym

Oct. 07, 2024

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Top 10 questions you should ask when purchasing a ...

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.

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.

Additional reading:
How To: The Top 10 things to consider when selecting ...

The company is the world’s best industrial process control valves manufacturer supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

How To Choose The Right Process Control Valves

What Are Process Control Valves?

Control valves are critical to the establishment of an efficient process and smooth running over the lifetime of a system. The controller sends signals to the valves which can change the size and direction of fluid flow, and in turn affect other process parameters, such as liquid level, temperature and pressure.

How To Choose The Right Process Control Valves

The many different types of process control require valves of all sizes, types, materials and modes of actuation. Knowing how to choose the right process control valves might seem a little daunting. You will have to consider technical specifications such as the level of control a particular valve will provide, its delivery time, and the amount of resolution it can achieve, not to mention its life expectancy and maintenance requirements. Your choice will also be affected by cost, and may demand application-specific expertise.

An additional factor to evaluate is how versatile the valves may be; whether they can cope with a wide range of different flows and still maintain stable flow control. They may be required to have connectivity that enables remote monitoring and technology that makes them easy to maintain. In our experience at Rowse Pneumatics, we have found that linear angle valves and rotary valves offer the most wide-ranging applicability.

Linear Valves

Linear valves are simply designed and easy to maintain. They are also extremely versatile, offering a wide range of pressure classes, sizes and design options. Linear valves are typically more expensive, usually using pneumatic or hydraulic actuators. However, they are also more resistant than rotary valves to cavitation, erosion and excessive noise. They tend to operate more slowly, but have greater accuracy and positional stability of the closure element. Linear valves can be cage-guided, stem-guided or top/bottom-guided.

Linear Angle Valves

Linear angle valves are a type of globe valve where the inlet and outlet ports are situated at right angles to each other, and are often used in tight spaces. In this type of valve; a closure element, a slat, a disc or something flexible like a diaphragm is moved in and out of the angled valve seat by means of a linear actuator. The valves can be cage-guided or stem-guided, and have a range of design options. These include restricted trim, expanded outlet connections for low-flow applications, and outlet liners that help to resist damage. They are best suited for more demanding applications, where noise, large flow rates and flashing can be more easily mitigated with appropriate technology.

Linear Globe Valves

Linear globe valves are a popular choice for their noise-mitigating properties, their ability to regulate a wide range of flow requirements, and their internal accessibility which allows easy maintenance. A spherical body typically contains a stationary ring seat with a cylindrical or disc-shaped plug element. These valves are available in all design styles, with top/bottom-guided and stem-guided valves being more suitable for general industrial purposes and less demanding applications. Cage-guided valves perform well in a wider range of applications, and can be fitted with mitigating features for noise and cavitation, but they tend to be more expensive. All types of globe valve can be controlled by all modes of actuation, making them a great deal more versatile.

Three-Way Control Valve

Linear three-way control valves are commonly used in industrial applications, and have a combination of one and two inlets and outlets, which enables one-into-two fluid separation or two-into-one mixing. This type of valve is usually cage or stem-guided, and is used to control the amount of pressure or flow in between two sections of the piping system. Typically, this valve is not used in very demanding applications, being more suited for things like boilers, water chillers, fan coils and air-handling units.

Rotary Valves

Rotary valves regulate flow by rotating one or more passages in a transverse plug. They can incorporate a wide variety of adaptive technology, which makes them very versatile. They typically offer a less tortuous inline path than linear valves, while still providing similar rangeability, flow control and severe-system resilience. Their design is inherently advantageous to applications with actuating fluid which may contain particulates and can't be kept scrupulously clean.

Other Factors To Consider

The prevailing standards of the country and industry must be taken into account when deciding how to choose the right process control valves, as well as the varying expectations of different customers. The priorities of the end-user are the most important. This usually means a versatile, robust valve, combining the necessary degree of control with a long service life and the greatest ease of use and maintenance.

Standardised performance is also desirable to make repair and replacement of parts more straightforward. Valves should be able to perform equally well in a wide range of fluid environments: clean, dirty, abrasive, corrosive or viscous, and at high temperatures or pressures. While incorporating a filtration unit in such environments is possible, it makes the system more complicated and requires an additional maintenance programme.

The valves must be capable of consistent, stable flow control in all conditions so as to prevent production downtime. They must match the specific control characteristics required for their particular process conditions, such as load, linear parameters and equation. Valves must also be able to handle the entire range of potential flow changes that occur in the process. They should have adequate and compatible connectivity to a management system, to enable remote control and monitoring of processing applications.

Process control valves should also be selected with ease of proper maintenance in mind, including:

maintenance access without the valve body having to be removed from the system
inspection and adjustment access to the valve packing
easy disconnection and reconnection from the actuator, such as coupled or splined shaft connections
shaft protection which should be blowout-proof
self-purging, enclosed actuator linkage
self-aligning seat ring to ensure tight shut-off

Taking all these factors into consideration is no easy task, but it's a necessary one to ensure you choose the right process control valves for your particular circumstances. If you have any queries or concerns about your selection, our expert team at Rowse Pneumatics will always be happy to help.

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