Category Archive: Check Valves

Benefits of the WLC® Wafer Style Silent Check Valve

Typically used to restrict fluid flow to a single direction, check valves play an integral role in all types of liquid networks. At DFT® Inc., we’ve been manufacturing top-quality check valves and control valves since 1943. The DFT® Model WLC® Wafer Style Check Valve, a spring-assisted, lightweight model, offers a number of unique advantages over traditional valves.

The dual/center-guided design improves stability, while the disc and seat arrangement ensure a tight shutoff, eliminating the risk of reverse leakage and, therefore, preventing potentially dangerous water hammer. In fact, these valves are ideal for use in systems with a high risk of water hammer. Offering consistent, reliable operation and ensuring low maintenance costs, the WLC® product line can be used for a wide range of pressure/temperature combinations, making these valves ideal for applications involving liquids, gases, and steam.

Wafer Style Check Valves

As mentioned, DFT®’s wafer style check valves are specifically designed to prevent water hammer and reverse flow. Take this recent project as an example:

One of our clients approached us for assistance with an application involving raw water intake; the valves they were using were causing water hammer, and they needed an alternative solution to ensure optimal operational efficiency and reduce the risk of costly maintenance needs and downtime. We replaced the valves with our WLC® models and later assessed the facility during a routine maintenance operation. The water hammer had been completely eliminated. Simply by switching to these check valves, the client was able to fix an issue they had been dealing with for years, significantly reducing the risk of mechanical failure and ensuring optimal cost efficiency.

The WLC® check valves are available in a variety of ASME classes, and can be utilized in pipes of different line sizes. These valves can also be manufactured with a range of different materials for various types of applications. DFT®’s WLC® models meet stringent industrial standards, such as MSS-SP 61(for seat leakage) and MSS 126 and API 594 (for face-to-face dimensions).

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Versatile, reliable, and lightweight, the WLC® line of check valves is specifically designed to reduce the risk of water hammer and its various related issues. Allowing for low maintenance requirements and consistent service, these valves available at DFT® serve as ideal solutions for a huge range of industries and applications.

To learn more about these unique valves, download our WLC® cut sheet today.

Why You Should Replace Your Swing Check Valve With a Silent Check Valve

Used to restrict fluid flow to a certain direction, check valves are employed in the vast majority of industrial processes. At DFT® Inc., we provide a wide range of check valves for use in diverse industrial applications. Our spring-assisted in-line check valves, for instance, are specifically designed to prevent water hammer by eliminating the risk of reverse flow. And, if sizing is done to account for flow rather than line size, these high-performance valves will operate reliably and efficiently for years, without the need for extensive maintenance.

In-Line Check Valves

The experts at DFT® often help clients assess their unique check valve requirements; our check valve sizing program allows us to easily determine required valve sizes before actual setup, eliminating the risk of design errors and delays. DFT® check valves can be installed in-line in any orientation; valve operation will not be hampered in any way by the specific orientation chosen, provided the flow direction is in line with the valve design (as indicated by an arrow on the valve casting).

However, for a downward flow, these check valves need to be modified slightly to support the additional weight of the disc and any static head that may be involved. While silent check valves can be employed in vertical piping or in installations requiring constant controllable pressure, swing valves should only be used in horizontal pipe runs, in which minor flow variations are expected.

When using swing check valves, users are afforded limited pressure control, as there is less control over valve opening and closing. Therefore, this type of valve is usually employed in less sensitive, large-scale pipelines carrying liquids, gases, or steam. To allow for enhanced performance, these swing check valves can be replaced by our GLC® Silent Check Valves or Excalibur® Silent Check Valves. These silent check valves have only one moving part and allow for greater flow variability than a conventional style swing check valve. Also, because the DFT Axial Flow Check Valves have so few moving components, they are more resistant to wear and tear and can maintain a longer lifespan.

However, the GLC® model is not considered a “dead-end” service valve. It is essential that the upstream, or seat end, of the valve be connected to the line until the pressure is relieved from the downstream end. The seat end of the valve must always remain bolted to the mating flange when the valve is exposed to downstream pressure in order to avoid possible blowout of the internals, as the retaining screws do not account for direct exposure to downstream pressure. In addition to eliminating water hammer, appropriately sized silent check valves can greatly improve system safety, protect critical system components like pumps, and improve overall system life while reducing maintenance costs.

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DFT® check valves are specially designed to improve the efficiency and safety of your industrial processes, and our team of experts is ready to assist in identifying the ideal model for your specific needs.

To learn more about our valve solutions, and why it may be beneficial to replace your current valves with DFT® non-slam check valves, download our new eBook, “Non-Slam Check Valves vs. Swing Check Valves.”

Steam Condensate: Important Things to Know

In our latest webinar, we provide an engaging, informative overview of steam condensate and its critical role in industry today. The webinar includes a short history of steam condensate, some of the most common problems that arise when utilizing it, solutions to those problems, and a survey of its many modern applications.

The History of Steam Condensate

The history section of our webinar discusses the origins of steam research, beginning with Thomas Savery, who invented the first steam engine in England at the end of the 17th century. He developed and patented it for use in pumping wells in 1698. Thomas Newcomen would later refine that invention in 1712, adding water tanks and pump rods so that deeper water mines could be accessed with steam power. In 1778, James Watt further built on these discoveries, employing a gearing system that allowed a steam engine to drive a flywheel in order to produce rotational power, spurring the development of the steam locomotive. These inventions, all originating in England, would become the catalyst for the Industrial Revolution and shape the world as we know it today, with steam power playing an instrumental role in a wide range of industries — including mining, chemical processing, petroleum production, textiles, pulp and paper production, and, most importantly, power generation.

The Basics of Steam Condensate

The webinar then describes the basics of steam condensate, answering the question: Why steam? The main advantages of steam stem from its high efficiency and ease of transportation and control, which make it an ideal medium for heat transfer. Steam power is easy to create due to the abundance of water and wide range of heating options available; simply by managing the temperature and pressure of steam, it can be used for much of the work that powers the industrial world. The three biggest users of stream power today are the power generation, pulp and paper manufacturing, and chemical processing industries; in these sectors, steam is used for all manner of jobs, including automation, dilution, fractionation, quenching, mechanical drive, and stripping.

Common Issues With Steam Condensate

There are some challenges involved in using steam condensate, however. For instance, it’s important to maintain high-quality steam in order to prevent a variety of pipe and valve issues, as low-quality steam can reduce heat-transfer efficiency by as much as 65%. Also, if CO2 combines with steam condensate, the formation of carbonic acid and CO2 gas may occur, which can cause rapid corrosion. Luckily, this can be managed through the use of steam traps, which keep water separated from the steam. Engineers and plant managers must also consider the line sizing of pipes in order to prevent condensate collection, as well as the location and configuration of equipment, the insulation methods used, and the types and quality of different valves used for different applications.

Steam Condensate Q&A

Below, we’ll delve into some of the most common questions we receive regarding steam condensate.

• Q: Do you propose using traps for all piping loops with low points in offsite piping?
• A: Yes. The condensate must be removed from the lines in order to prevent water hammer or corrosion of the piping itself.

• Q: Can you share some guidelines for specifying cracking pressure? Is there a tool one can use?
• A: It’s best to work with directly a manufacturer to pinpoint the best low cracking pressure options for your specific application. In-line (silent) check valves typically have a cracking pressure of approximately 0.5 psi. Depending on the condensate return piping layout, a standard cracking pressure (CP) valve may allow excess condensate to accumulate. In these scenarios, a lower CP is ideal; options will vary from manufacturer to manufacturer. At DFT, we offer solutions that allow for a CP as low as 0.1 psi.

• Q: Are there any formulas or tables available for steam pipe sizing?
• A: We recommend the reference handbook, “Crane Technical Paper No. 410.”

• Q: Are low cracking pressure check valves only necessary in certain types of steam systems?
• A: Low cracking pressure valves should be used for condensate return lines, not main steam lines. Also, low CP valves will help reduce the accumulated condensate in return lines.

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All of these matters and more are discussed in our comprehensive online webinar and its accompanying slides. To learn more about steam condensate, view DFT’s prerecorded webinar today.

Valve Value: The Return on Investment (ROI) of Quality Check Valves

Fluid system management requires a complete approach; if any component is compromised from the pump to valve to pipe and back again, flow can suffer. In-line management, including products such as check valves, can be challenging — after all, they can be a major purchase. However, the lifespan, safety, and efficiency of your system require careful investment.

Not all check valves function or cost the same. A check valve’s long-term return on investment (ROI) is a major factor and can be significantly more important than upfront cost of these components.

Assessing Real Cost and System Lifespan 

Putting a system’s needs in perspective requires factoring in the unfortunate possibility of worst case scenarios and highest demands. In evaluating your component needs, remember to factor in:

• Maintenance
  The cost of maintenance can be high in time, money, and human resources, especially if parts need to be regularly maintained.
• Down Time
  The worst case scenario for production managers — system failure — demands necessary valve repair or replacement. The resulting downtime comes at a high cost to an entire facility.
• Media Demands
  Do you handle a highly acidic or caustic application? You may require a higher-grade alloy than standard 304 or 316 SS (stainless steel) for chemical resistance and system component lifespan extension.
• Water Hammer Problems
  Sometimes a side note in engineering, water hammer can cause serious damage to piping, valves, and pumps, resulting in unwanted shutdowns. Custom sizing your valves and using DFT silent check valves can help manage water hammer issues.

The Real ROI: High Performance Check Valves for Optimal System Performance

At their most basic level, check valves are smart components designed to allow fluid to flow in one direction and prevent back flow in the other. They are self-automated, driven by pressure as opposed to an operator.

On the surface, it would appear that the more complex the check valve, the higher the price tag —but is that an accurate conclusion?

Bearing in mind the considerations above, our value experts take ROI seriously. In a study evaluating the performance of swing check valves versus the more high-tech axial flow silent check valves over a 20 year period, we found that the utility facility had a significant savings over time using axial flow silent check valves.

Comparing initial cost of components to lifespan, the system’s superior performance using axial flow silent check valves reduced annual maintenance costs. In fact, the valves worked so well that they led to an 85% reduction in overall operating costs at the facility!

Making a Case for High Quality Components

The utility facility our team tracked is far from the only example in the field. Real world applications abound, reinforcing the idea that high quality check valves can lead to superior performance. Our value team has found that better-made, sophisticated components offer reduced maintenance expenses, long lifespans, and reliable valve and fluid system performance in countless cases, including:

• A United States chemical facility struggling with a water hammer. They replaced worn out, double door check valves with three 10”, 150/300# ALC check valves and completely eliminated the problem — their system has been running smoothly since 2012.
• A food processing facility that has relied on the DFT SCV Check Valve since the 1950’s for sanitizing management. It met safety needs and industry criteria as a leading technology then and now.
• A petrochemical plant with high cycling and system failures. They replaced failing swing check valves with the DFT model GLC Check Valves, custom-sized for the application. DFT valves minimized the chattering and excessive cycling previously disrupting the system.

Investing with Smart Components at DFT

Do you want to prevent check valve failures but have concerns about cost? Our check valve experts and value team are here to help you with sound engineering and upfront investment evaluations. Reach out to contact an expert today, and we’ll guide you through the best valve solutions to fit both your application and your budget.  

Customizing Your Condensate Line Check Valve for Low Cracking Pressures

Understanding Low Cracking Pressure in Condensate Lines

One of the most common issues in steam systems is the pooling of steam condensate — a byproduct of all steam processes — inside of the equipment. When released from a high-pressure area to a low-pressure area, pooled condensate can flash, or quickly heat back up into steam, resulting in extreme pressure spikes, audible banging noises, valve and steam line failure, and even full equipment failure.

To mitigate these risks, manufacturers in the chemical processing industry incorporate steam traps and condensate drain systems into their equipment. These applications also utilize in-line check valves in the condensate system piping to allow flow in only one direction — from low pressure to high pressure — before sealing.

Cracking pressure, or the minimum upstream pressure at which the valve can operate, is a critical aspect of check valve applications. To help manufacturers ensure they use the best components for their processing system, check valves can be designed and specified for unique cracking pressures.

Customizing Your Condensate Line Check Valve

There are a few key considerations to keep in mind when selecting check valves for steam applications. Important factors include:

• Sealing ability
  • Resiliency — Resilient, reliable seals will provide a long-lasting, leak-tight seal through the use of engineered elastomers; these seals are highly resistant to abrasion and are mainly used for low-pressure environments (up to 500 psig).
  • Metal-to-metal — More reliable for piping systems with temperature and pressure changes, metal-to-metal seals are able to withstand higher contact forces and pressures (exceeding 500 psig).
• Non-slam characteristics — The valve must be able to close quickly to prevent the reverse flow that can result from steam condensate flashing. Factors that influence non-slam characteristics include:
• Disc location in the full open position
• Length of stroke to close
• Presence of a closure mechanism, either internal or external to the valve
• Orientation of the valve and piping

To learn more about methods for eliminating steam condensate issues in chemical processing operations, download a copy of our eBook, “The Challenge with Steam Condensate.”