Make the move from analog to digital temperature measurements

Editor’s note: This is Part One of three temperature articles to accompany the July Tech Update on Temperature Monitoring and Control. Part Two looks at linking process control with building, refrigeration and environmental control systems while Part Three considers IIoT and wireless temperature monitoring and control.

Another article entitled “No spiral freezer should be an island of automation” and written for this series by Ivy Arkfeld, energy engineer for VaCom Technologies, showed how integrating a spiral freezer with process and refrigeration controls increases efficiency, speeds production and saves energy.

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Moving from an all-analog means of keeping track of process and storage temperatures can provide numerous benefits—for example, getting more robust measurements with higher stability, reliability and accuracy. In addition, you get better diagnostic information from the sensors themselves, and this information—coupled with temperature and other process variables—can help you get a better grip on your process and on maintenance, too.

Suppliers and system integrators (SIs) stand ready to help. Suppliers, which have firsthand experience with unique applications, can provide solutions to what may seem an insurmountable challenge, for example, how to employ sensors when process penetration is not allowed due to required compliance with hygienic standards, says Kevin Stultz, global product manager, Rosemount Temperature, Emerson Automation Solutions. Suppliers can also assist with the setup of wireless networks to allow for better process coverage, usually with lower installation cost compared to many wired solutions.

Moving to digital must make sense

First, assess the maturity level for the digital adoption, says David Parker, chief evangelist for Cloudleaf, a supply chain system provider. First thing any system integrator (SI) will do is understand a manufacturer’s process today and how much can be accomplished by putting a new technology in place to overcome existing issues, for example like manual scanning.

It must make financial sense to invest the capital to move to a digitally controlled, automated temperature control system, says Steve Malyszko, co-founder, Malisko Engineering, a Control System Integrators Association (CSIA) certified member. Once the processor makes that commitment, then it’s time to consider also making the incremental capital investment to leverage the value of installing a data historian to capture the actual temperature measurements of the critical temperature control points in their process in real time.

What are some of the ways moving to digital from analog makes good financial sense? “Digitally managing temperature can help you achieve business goals like reducing cycle time, preventing product damage, and improving data collection of storage for regulatory reporting,” says Dan Reinarts, industry technical consultant, Rockwell Automation.

For smaller processors, there are solutions that are digital, wireless and simple to use. Adam Fleder, president of TEGAM, suggests a wireless thermometer, which has an included phone app and cloud storage, enabling immediate data storage with no additional purchases. Medium-size and large processors can use their existing QMS and TEGAM’s software development kit to customize applications.

Look at current methods and make some plans

In making the analog-to-digital move, one of the more important steps for a manufacturer to take is analyzing the processes it has in place when the staff takes temperature measurements, says Nick Mecham, VP, business development, Monnit Corporation. “Are there actions needed at certain thresholds? What’s the required frequency of assessments?”

“Understanding the critical data points ahead of time allows for proper planning,” says Robert Villarreal, Endress+Hauser product marketing manager – temperature and system products. “Data should always be actionable information, otherwise, it risks becoming overwhelming or useless information.” System planners also need to understand who else and what other processes may utilize this information and why it’s important.

“Before you start evaluating digital solutions, you should manually collect data and current procedures to estimate the potential financial benefit,” adds Reinarts. As part of this process, stakeholders should capture requirements for the project and any ideas for improving workflows.

These requirements need to be accurately integrated into the digital monitoring system a processor has selected. Once that’s done, the processor’s staff will be able to determine if it’s best either to migrate completely to a new digital platform or integrate wireless sensors into the existing platform, says Mecham.

There’s an integration process when moving from manually inputting temperature data to digital collection, adds Mecham. “This is where a system integrator becomes vital. SI’s help bridge the gap between the new digital monitoring platform and the customer’s existing data platform if they wish to stay with that.”

A system integrator is invaluable in a situation like this, says Joshua Eastburn, director of technical marketing, Opto 22, a CSIA partner member. A good SI or automation vendor partner will be able to walk the user through assessing the current state of processes, the applicable technologies, the front-end engineering design and the financial planning required to bring the system into being.

Select an integration partner

Selecting an experienced automation partner may require interviewing current and new service providers, says Reinarts. “When discussing your requirements with a potential partner, it’s important to know their industry experience and regulatory knowledge.” For example, a supplier or system integrator must be able to articulate the advantages of the different software, hardware, communications media and protocols offered for temperature control. A 4-20ma signal may be all that’s needed but understanding the benefit of HART will allow an informed decision. If there are regulatory requirements on digitally stored data, it’s also essential they be able to describe how each of those requirements are met.

What should you look for in a SI? Ryan Beesley, CAP, regional engineering manager for Concept Systems, a CSIA certified member, suggests seeking out a SI with strong process controls expertise. A SI that has the skills and experience necessary typically will have a few characteristics:

The SI is a member of a professional group, association, or society that speaks the language of process controls, e.g. Control Systems Integrators Association (CSIA) or the International Society of Automation (ISA). Being a member of these organizations ensures that the SI is adhering to the standards and methodology that is common to the industry.
The SI has engineers on staff that specialize in automation controls and control systems. Processors should look for SI’s that have ISA Certified Automation Professionals (CAP) or Professional Engineers specializing in control systems, known as control system engineers (CSE). Both are either certified or licensed in conjunction with ISA, the founding organization for all process controls engineering standards.
The SI should have a strong methodology that follows best practices and standards for project execution. Typically, these SI’s follow CSIA or ISA project execution models through all steps of a project; from the onset of the project planning phase through the project execution phase. With that, they must have the experience required for doing the conversion. Look for a SI that not only has the capability to design and spec out devices but also has experience in installation, commissioning, parameterizing, integrating, and maintaining these devices. A SI that has been heavily involved in all these steps will know what works best for each application—as well as what doesn’t.

Sometimes processors and SIs may have to work with what’s already in place in doing a conversion. “In replacing mechanical temperature instruments, if there are thermowells in place, which may be difficult or impossible to remove (some are welded in), it is important to replace the mechanical instruments with measuring probes and connections that will fit that same thermowell, says Alan Clark, Palmer Wahl Instruments, Inc. applications engineer. Electronic sensors offer the option to allow remote mounting of the temperature indicating display, using either wired or wireless transmission of data. Issues to be considered are:

Is there power available or are battery powered units required?
If remote mounted, how far away do I need to mount the display unit versus the measuring probe?
What kind of accuracy does the processor want?
How much are they willing to spend to give them better performance and control that will give better product and save money in the long run?

A typical accuracy increase will be on the order of three to ten times better, depending on what they were using previously versus the new system, says Clark. RTD temperature sensors are typically five to eight times more accurate than a thermocouple based system and will also be much more stable against drift, long term.

Temperature monitoring everywhere

While we’ve highlighted some of the reasons and steps to take in making the move from analog to digital to monitor your process, digital offers some key benefits in providing a way to integrate your process control system with building control and HVAC systems and monitoring the temperature of your goods while in transit. We’ll look at these plus IIoT and single-point solutions in coming stories.