Check valves are typically thought of as a very simple component of a hydraulic process. They permit the flow of fluid in one direction and prevent flow in the opposite direction. Simple, right? However, these devices can be one of the best fail safes your process has against a very costly shutdown. Faulty valves can have enormous consequences if they are not functioning with the utmost precision.

Beyond flow control, check valves may also be used as a directional or pressure control in a system. If the pressure becomes higher on the wrong side of a valve, it will close and block flow in the opposite direction. This means the check valve will stop pressure spikes back to the pump. Depending on your process, fluid can flow from a pump through the system at very high speeds. If something in the process suddenly causes the fluid flow to be restricted, the pressure in the line can quickly increase by two to three times, causing damage to the system. The check valve should then close and block the pressure spikes back to the pump.

A check valve can end up costing companies thousands of dollars in replacement pumps and exponentially more in machine downtime. Downtime is one of the largest sources of lost production time in industrial processes and unplanned downtime can be one of the greatest expenses. When unplanned downtime happens, the cost of overhead is still there being consumed, and no value is being produced. These are the most obvious costs of unplanned downtime, but what about the underlying costs as well? Downtime also throws inventory levels off resulting in less than optimal on hand inventory which can lead to increased operational costs. Also, when employees have to focus on fixing a downtime issue this takes away from time they could be using to innovate and create growth opportunities for the company.

One of the highest concerns of a check valve failure is the safety. If a check valve fails, the potential for leakage or even a blow-out is a possibility. A blow-out occurs when the shaft-disk in the valve experiences a separation. This type of failure has occurred even when valves are being operated within their temperature and pressure limits, further justifying the utilization of a high quality product. While a catastrophic blow-out from a faulty valve may be rare, even the smallest of leaks can create safety hazards that can be dangerous for the operators. Ensuring that your check valves are well maintained, and of high quality can help mitigate these risks.

Parker C-Series Check Valves have fully guided poppets. Their superior design eliminates wobble and erratic travel that can commonly occur with less durable ball check constructed check valves. The soft seal poppet on the check valves are standard for sizes up to 1/2” NPT, #10 SAE. They can withstand pressures up to 5000 PSI and flow rates up to 150 GPM. Customers around the world recognize the Parker brand as the benchmark for high performance and best in industry quality. In a product as small as a check valve, performance and quality can lead to big savings in the industrial process.

Parker C-Series Check Valves and N-Series Needle Valves are now available for purchase on Parker.com. Simply add products to your cart for shipment within two days for in-stock items.

Article contributed by Matthew Davis, to be named, product sales manager, Hydraulic Valve Division, Parker Hannifin Corporation.

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• Dynamic metrology – applications where measurement data is collected while either the measurement sensor or the unit under measurement are in motion
• Static metrology – applications where measurement data is collected while both the measurement sensor and the unit under measurement are at a stable location
• Focusing – a special type of static metrology where an axis, typically vertical, is used to focus on a sample for measurement

A history lesson isn’t necessary to know manufacturing has evolved over time. From the advent of mechanics to the electrification of factories for mass production to equipping production lines with robotics, the world of machines and processes is evolving before our eyes once again.

Manufacturing facilities are getting leaner. This isn’t by design. Baby Boomers who once dominated the landscape are now exiting the workforce in droves, so much so the industry is facing a deficit of 3.5 million workers. This has put a strain on organizations as they seek younger and less experienced personnel to do more with less. Since many manufacturers are operating with smaller staffs, equipment processes and manual checks are falling through the cracks.

Plant floors are less staffed, but more connected than ever before. Thanks to the Internet of Things (IoT), data is available at our fingertips to harness and apply the information into predictive analytics to achieve higher levels of intelligence, orchestration and optimization. Logically, this led to condition monitoring.

A major component of predictive maintenance, condition monitoring presumes machinery will deteriorate and eventually breakdown. By being proactive and monitoring the performance of equipment through technology, data can provide the information to strategically schedule maintenance before an issue creates unexpected downtime. This prevents consequential damages and ensures the reliability of machines can remain high.

Condition monitoring utilizes various process parameters such as temperature, pressure, humidity, current, vibration and flow along with fluid media samples to monitor performance. Over time, these indicators of system and equipment health will become more predictable, reducing unscheduled downtime and increasing product integrity.

To achieve condition monitoring and a predictive maintenance program, it’s not enough to purchase test instruments and put them in the hands of untrained personnel. It’s imperative to let go of tried and tested methods and establish a new culture and approach of looking at maintenance. This means constantly developing, implementing, managing, measuring and improving condition monitoring. It requires commitment and full participation, otherwise the vision is lost and the chances of a successful program decline. There are five things you need to know to ensure your condition monitoring program is prosperous.

Read our new white paper, "Why Preventative Maintenance is Holding You Back" to discover how condition monitoring tools allow manufacturing organizations to predict the future, reduce their costs, and do much more with less.

Which equipment are you going to monitor? You’re not going to pick random machines to evaluate. An Equipment Criticality Ranking (ECR) and/or Reliability Centered Maintenance (RCM) should be performed. An ECR identifies and addresses potential risks associated with the operation of the processing facilities. Failure scenarios are pinpointed, ranked and quantified in relation to the safeguards that protect against the scenario. The RCM focuses on avoiding the failure consequences, not the failure modes by ensuring systems continue to do what its users want in its present operating context. These are comprehensive lists of assets sorted in a ranked order and helps identify and determine which equipment should be tested on a regular basis. By performing ECR and/or RCM, organizations can develop unique maintenance schedules for each critical asset.

Choosing the appropriate personnel to be involved in predictive maintenance and condition monitoring is crucial. A common mistake organizations make is hastily assembling a team of their best mechanics rather than seeking the right technician who has the key attributes to master technology and perform investigative work. The selection of a condition monitoring team is handled in different ways from one organization to the next, but should include individuals who demonstrate loyalty, intelligence and always pursuing training and self-development.

Technicians involved in a predictive maintenance program receive little if any training beyond the information instructed by the vendor system. In fact, personnel seek valuable training that directly impacts the effectiveness and success of the program. It’s crucial that all individuals are educated and can demonstrate the skillset to operate equipment, interpret the data, and report the information in a clear and concise way. A shortfall in this area will affect the quality of the overall initiative.  

Practice makes perfect. The same holds true for condition monitoring. There are a number of variables that can affect the accuracy of data. When it comes to testing equipment, collect data in the same location and on the same surface utilizing the same instruments to ensure consistency. Also, reviewing and interpreting information should be conducted in a timely manner. Otherwise, this will lead to unidentified equipment failures and unscheduled downtime.

You’ve inspected the equipment and collected the data, now what? It’s time to take action. Sounds simple enough, but there are many organizations who fail to take corrective action when machine anomalies are flagged. A predictive maintenance program receives the necessary support and funding to ensure success.

In today’s smart manufacturing world, condition monitoring is essential to determine machine health and implement the correct maintenance to ensure maximum performance and longevity. However, this cannot be achieved without having the right equipment, people, training and execution in place. Without a strategic plan, condition monitoring and predictive maintenance can become a wasted resource rather than a benefit component of your operation. 

Learn more about condition monitoring strategies on your plant floor.

Article contributed by Dan Davis, product sales manager, SensoNODE™ Sensors and Voice of the Machine™ Software, Parker Hannifin Corporation.

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In today’s industrial manufacturing environment, hydraulic cylinders are complex devices that incorporate a wide range of components available in a multitude of sizes, configurations and materials. When it comes to complex hydraulic systems, cylinder specification can be a balancing act for OEM design engineers — as each design factor influences one or more of the many other design details to be considered for the application.

Even though hydraulic system design guidelines like NFPA and ISO exist, many industries have developed their own. Certain cylinder manufacturers offer options that present a wide scope of performance capabilities for standard components, minimizing the need for customization. However, exceptions to this remain. Working with an experienced engineering manufacturer can help to navigate and expedite the design process.  

In this blog, we’ll look at some of the many factors that should be considered when specifying hydraulic cylinders and how to simplify the process. 

To read all of the factors to consider when specifying hydraulic cylinders, download the white paper “The Art of Cylinder Specification”. 

Medium-duty hydraulic systems with pressure capabilities of 1000 PSI are used in the majority of industrial applications. Some applications, such as hydraulic presses and automotive manufacturing require heavy-duty systems. Standard heavy-duty hydraulic cylinders can accommodate pressures as high as 3000 PSI. Load capabilities are relative to the full piston area (in square inches) when exposed to fluid pressure multiplied by the gauge pressure in PSI. 

Pressure rating can be a concern with custom stroke distances above 10 feet (3.05m). To handle the load, rod diameter must be determined. A pressure rating on load in thrust (push mode) may need to be specified. Rod sag from horizontal applications may result in premature rod bearing wear. To optimize hydraulic system performance, a best practice is comparing the positive effects to any potential negatives. 

The definition of “excessive speed” can vary from one design engineer to another. As a good rule of thumb, standard hydraulic cylinder seals can easily handle speeds up to 3.28 feet (1 meter) per second. The tolerance threshold for standard cushions is roughly two thirds (2/3) of that speed. For higher speed applications, a standard low-friction seal is the better choice. But, what you gain in one aspect of performance, you lose in another. The greater the fluid velocity, the higher the fluid temperature, so when opting for speed increasing customizations, it is essential to consider the impact of higher temperatures on the entire hydraulic system. In some hydraulic systems, over-sized ports may eliminate escalated temperature concerns.
 

Hydraulic cylinder systems using standard components can be designed to meet application temperatures as hot as 500°F (260°C) and as cold as -65°F (-54°C). But temperatures affect both the “hard” and “soft” design components of cylinders. Applications requiring temperature extremes at either or both ends of the temperature spectrum require extensive knowledge of the interdependence of individual components to achieve the best balance of short- and long-term performance expectations. For example, applications near the north or south poles will see a contraction of the seals and metal parts due to the extreme temperatures.

There are basically three categories of mounting styles. Fixed and pivot styles can absorb forces on the cylinder’s centerline and typically include medium-duty and heavy-duty mounts to accommodate thrust or tension. A third category of fixed styles allows the entire cylinder to be supported by the mounting surface below the cylinder centerline, rather than absorbing forces solely along the centerline. Several standardized mounts are available within these categories. OEM design engineers can use these various mount offerings for a wide range of application requirements. NFPA Tie rod cylinders, which are used in the majority of industrial systems, can usually be mounted using a variety of standard mating configurations from trunnion-style heads and caps to extended tie rod cap and/or head end styles, flange style heads, side-lug and side-tapped styles, a range of spherical bearing configurations, and cap fixed clevis designs. Most mounting options are available for both single acting and double rod cylinders.

The goal of every mounting design is to allow the mount to absorb force, stabilize the system and optimize performance. Cap end mounts are recommended for rods loaded primarily in compression (push). A head end mount is recommended for rods loaded in tension (pull). The amount of tension or compression determines the piston rod diameter. The amount of pull or push determines the bore diameter. Other relevant factors to consider when selecting a mounting style include:

• Load

• Speed

• Cylinder motion (straight/fixed or pivot)

Every mounting type comes with benefits and limitations. For example, trunnions for pivot-mounted cylinders are incompatible with self-aligning bearings where the small bearing area is positioned at a distance from the trunnions and cylinder heads. Improper use of this type of configuration introduces bending forces that can over-stress the trunnion pins. Many performance expectations that appear to require atypical mounts can be accommodated by existing styles, sometimes with only slight modifications — facilitating replacement and reducing costs. 

Bore size is related to operating pressure. The amount of push or pull force required is what determines the bore size needed. Earlier generations of steel and aluminum mill equipment often required the use of non-standard bore and rod sizes. Today, virtually every industrial requirement can be met with NFPA standard and/or ISO-compliant components.

OEM design engineers probably request customization of piston rod sizes more frequently than any other hydraulic cylinder component. What is not always considered is the simple fact that push or pull is never independent of stroke length. Just as a pushed rope holds a straight line only in relation to its length (the longer the rope, the more the rope curls), piston rods under compression or tension tend to diffuse force in non-linear directions. Specifying costly materials such as stainless steel or alloy steels for the rods themselves is unnecessary. In most extreme applications, chrome plating provides a high level of corrosion-resistance required to optimize system longevity. 

In conclusion, hydraulic cylinder specification can be a time-consuming and complicated process. Partnering with an engineering manufacturer experienced in hydraulic system design, such as Parker Cylinder Division, early in the design process, an OEM design team can save time and money and ensure reliable system operation and long service life.
 

Download the white paper “The Art of Cylinder Specification” to read all of the factors to consider when specifying hydraulic cylinders.

​This blog was contributed by Jim Hauser, senior engineer, and Rade Knezevic, division sales manager, Parker Cylinder Division.

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