Pneumatic safety technology and the IIoT
How IIoT principles, along with appropriate pneumatic technology, offer machine safety and operation enhancements.
Pneumatic technology already encompasses several safety features and components to protect operators and equipment, prevent downtime, improve reliability and extend operational life. With the advent of the Industrial Internet of Things (IIoT), pneumatics technology is becoming even more functional, with new capabilities in tracking and measurement providing even greater insight into machine operation and the performance of components and subsystems. With this additional functionality comes a richer opportunity to also monitor machine safety characteristics and protect people and equipment from harm.
Pneumatics and safety
Machine manufacturers and end users have always used pneumatic devices to provide cost-effective and efficient motion and actuation on a wide range of systems; pneumatics also have provided original equipment manufacturers (OEMs) and end users with reliable, lightweight and proven technology to improve the safety of their equipment. Pneumatics can be used to implement many important safety functions, such as ensuring a limited speed, reducing pressure and force, safely releasing energy and guaranteeing a safe direction of travel or blocking a movement.
Machine builders in every region of the globe are seeking to leverage a variety of alternative technologies to improve machine safety — and pneumatic motion is a big part of that trend. Meanwhile, the globalization of the machinery marketplace means that machines must satisfy various safety regulations. As an example, in the European Union, the Machinery Directive (2006/42/EC) must be followed by law when a piece of machinery is put into service. The best way to satisfy the law is to follow the many global standards available.
The predominant regulatory standard that affects pneumatic technology in machine automation is ISO 13849, which outlines safety requirements and provides guidance on the principles for the design and integration of safety-related parts of control systems.
These regulations exist to help reduce the risk of personal injuries and help prevent damage to equipment. But, with regards to safety, companies have a huge financial stake as well. The U.S. Centers for Disease Control and Prevention (CDC) and the National Safety Council (NSC) estimate the direct costs of a fatal injury to be a million dollars or more, with indirect costs — like workplace disruptions, loss of productivity, worker replacement, training, increased insurance premiums and legal fees — running 2 to 17 times more.
Therefore, whether machines are made in Europe and shipped to the U.S. or vice versa, they need to follow safety standards. Pneumatic technology for safety helps machine builders meet the regulatory requirements.
The new factor: The IIoT
The emergence of the IIoT and related trends like Industry 4.0 are creating additional opportunities for pneumatics to enhance its contributions to safety.
IIoT is all about gathering data, opening new opportunities for tracking, measuring and reacting, thus gathering data that leads to information-driven outcomes. These additional information-gathering capabilities offer new opportunities to enhance functional safety in manufacturing. One of the benefits of the IIoT revolution is a more predictable state of manufacturing, which leads not only to manufacturing optimization but also enhanced safety algorithms.
One of the key developments associated with the emergence of IIoT and Industry 4.0 is the expanding use of sensors throughout automation systems, including pneumatic components. Sensor technology has become smarter, smaller, more lightweight and easier to integrate into a range of pneumatic components, allowing measurement of temperatures, pressures, flow rates, cycle times, valve response rate and so on. Even the simplest devices may at some point be providing some crucial information. As a result, end users will be able to know much more about the performance of pneumatics in their machines and devices.
Data alone is not enough
The more intelligent a system is, the more data analytics the system will be able to offer. And the more systems a factory has, the more data it will produce. To keep all that data from becoming overwhelming, equipment manufacturers and end users need to determine exactly what information is needed to ensure the safe and effective operation of their equipment.
In a pneumatic system, it’s not unusual for a machine to have 15 manifolds with 10 or more valves on every manifold. If one simply monitors how many times the valves have shifted, the generated data would not only be massive but also have limited usefulness.
An alternative strategy is to monitor the response time of a valve, a parameter that also is used to satisfy the requirements of the ISO 13849 functional safety standard. In the above example, the simple act of monitoring the number of times that the valves shift could not exclusively be used to predict the impact to the safety of the system. For instance, the action of an automobile manufacturer boosting production on an assembly line from 60 to 65 vehicles per hour, also would impact the system cycle time and thus affect the valve shift cycles, but not the valve’s response time.
Therefore, the manufacturer’s goal should be to develop enhanced safety outcomes based on appropriate data, which, when correctly analyzed, leads to application-pertinent information. Simply generating a large amount of data, without a plan of how to use it and understand what it’s measuring, is not very useful.
Mission time: A critical parameter
Mission time, as defined by ISO 13849 specifications and calculated using the cycle rate, hours of operation, days of operation and component reliability, is a critical parameter for measuring machine safety performance. It assures end users that safety-related components are going to function safely for an established amount of time, after which they must be replaced, regardless of whether they are still functional.
Unlike useful life, mission time is a design decision that is documented in a safety requirement specification and the validation portion of ISO 13849 and IEC 62061 specifications. While mission time is important, new IIoT capabilities make other information available that will also be helpful from a safety standpoint. For example, suppose a machine had a safety light curtain controlling a valve and the valve response time changed from 30 milliseconds to 50 or even 70 milliseconds, before the device reached its mission time replacement cycle. This scenario could pose a severe safety hazard, because it would allow an operator to get much further into the motion area of a machine before a safety response event could be generated. That decline in the valve response time (and the corresponding alert response time) is the kind of useful information that new IIoT capabilities would proactively capture and report.
Today, to keep systems and machinery safe, a scheduled maintenance plan must be in place and adhered to. It is this schedule that triggers the replacement or refurbishment of functioning safety-rated components in the machine or system. Autonomously monitoring the valve’s response changes over time makes the maintenance plan more in-depth and predictive. Thus, alleviating the need for scheduled maintenance altogether and still assuring that mission time is met. This “monitoring” of pertinent safety parameter changes can be done using IIoT principles and devices.
Whether it’s standard operational data or safety related IIoT data, the goal is to give actionable information. Different industries and production operations will have to determine what data is most relevant, and how to analyze and apply that data to improve their operations and safety systems.
The IIoT is here, now
Edge gateways are devices that translate data used by control applications into an IIoT format that can be used to connect to cloud systems. However, they also can be used for analyzing the data sent to them and thus are also considered to be edge computing appliances.
There already are some pneumatics products with edge gateway capabilities built into their electronics platform (see Figure 1). Many manufacturers are developing industrial IoT gateways that analyze various sensor signals and use the results to generate informative process information. To monitor the wear of a shock absorber in a pneumatic cylinder for example, the edge gateway would analyze the end-stroke sensor signals to evaluate the cushioning efficacy (see Figure 2). The system can intelligently route this information to the right people, without the use of the machine controller. This concept alleviates the need to modify the controller program which minimizes the risk of machine downtime and has the potential to substantially lower operating costs by identifying failing components before they stop and cause unscheduled downtime.
System performance data can be gathered with existing components and sensors and analyzed to provide pertinent information of the safety device or system, as well. For example, it is possible to track mission time by using existing sensors already on the components. However, for more granular data, component manufacturers will probably add more sensors eventually — either externally or internally to the devices or systems. Ultimately, there’s potential to monitor every level of a pneumatic system downstream of the compressor, including the safety-related parts.
One of the major benefits of the IIoT revolution is a more optimal and predictable state of manufacturing, but it also can be used to drive enhanced safety outcomes and safer manufacturing systems.
As a proven automation technology, pneumatics already offers many safety benefits. With the addition of appropriate sensors, analytics and connectivity options anticipated in IIoT applications, pneumatic technology adds even more safety enhancements that protect people and machines from harm (see Figure 3).
The role of component manufacturers is to work with end users to provide smart devices that deliver actionable, application-pertinent information that allows enhanced safety through information-driven outcomes.
IIoT Monitoring of a typical pneumatic system
Compressors: monitoring includes factors such as air temperature, pressure and moisture (potential dewpoints) and contamination levels (see Figure 4).
Filters, Regulators and Lubricators (FRLs): Sensors and monitoring are used to check for contamination, air temperature, pressure and moisture.
Manifold/Valve(s): Key items for monitoring include mission time, response time and cycle rate.
Cylinder: Cylinder speed, seal degradation and extend/retract times are other important factors to monitor.
Example: A linear cylinder extends out and pushes a box off a conveyor onto a pallet. As that cylinder degrades, there’s the possibility that it needs to be replaced. The stroke time from starting position to extended position may be established for a specific rate. If the readings drift outside that time window at some point, the system could issue an alert and provide actionable data to do something in response. The system could also monitor mission time with existing sensors. For example, if the manifold and valve are specified to run for six years, monitoring could be established to keep track of that timeframe, but also monitor valve response time and valve cycle rate.
Original content can be found at Plant Engineering.
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