The process of temperature management breaks down into three functions, observes Elizabeth Darragh of Sensitech: data collection; data storage; and analysis and reporting.
Paper strip chart recorders, she points out, provide an inexpensive means of collecting detailed data on temperature conditions over the duration of a product's journey. But at the trip's end that data, while easy to check visually, is not presented in a format that can be efficiently stored, accessed and analyzed.
Digital electronic monitors perform essentially the same data collection function, Darragh points out, but "are more sensitive, accurate and produce an electronic record that can be downloaded into a database, where data from multiple trips can be aggregated and analyzed in any number of ways over time."
This approach enables companies to see trends developing and identify patterns in temperature variations which can yield clues and specific information about the sources and causes of temperature violations.
A DC, for example, might notice that certain shipments of lettuce always arrive with an average trip temperature within the specified range, but also determine that temperatures spiked a couple of times in each trip for short durations to unacceptable levels. Armed with detailed data about exactly when and possibly precisely where-thanks to GPS-such temperature incursions occurred, the company might determine that a given carrier is letting its drivers put the reefer into fuel-saver mode during certain points in the trip.
For many in the perishables industry, RFID technology presents an ideal vision of what temperature management could become.
Though a big improvement over strip charts, electronic data recorders still require a great deal of manual intervention to check temperatures and to download and store the information for future use. And typically they only inform of problems after the fact, when product has already been compromised.
"With RFID technology there's no labor incurred trying to find the device in a box somewhere in the truck. When a truck pulls up to the back door readers mounted at the dock doors can automatically upload temperature data as soon as the door is opened," points out Tom Racette, director, RFID market development for Motorola Inc., Schaumburg, IL.
"There is even the means to transmit data electronically while product is still in the truck in transit. So you can actually take preventive action as soon as you're notified that a load is in danger of spoiling.
"And all the information that is being gathered automatically on temperatures at various points along the trip can help you pinpoint places where problems are tending to occur," he adds.
Some companies, including several Sensitech customers, already use RFID tags with dock-mounted or hand-held scanners to monitor perishables' temperatures in transit and/or on receipt, at least on a pilot basis, but the technology is still early in the development curve.
Among the latest trends is development of applications utilizing class 3 battery-assisted passive tags, which are less expensive with longer battery lives than class 4 active tags.
The varying costs of different kinds of tags and their readability characteristics help determine the specific applications where they might make sense. In some cases it's sufficient to include just one tag per truckload and in such a case a single data recorder may work almost as well.
But as companies become more rigorous about continuously monitoring temperatures of perishables in storage and in transit, they are discovering that temperatures can actually vary much more then previously suspected based on position within a truck, or even within a pallet, or in different locations within a cooler.
As a result, the ability to use monitoring technology like RFID tags and others, that can be more easily and cost effectively applied to smaller unit levels is becoming increasingly compelling.
Racette of Motorola, which is working with several customers in pilot projects, says, "Initially we're trying to go with one tag per-pallet. We're finding existing trials where companies are trying one tag per truck. But we think it's worth trying to get a little more granular visibility. Some day, as prices come down and RFID solutions advance, it may be possible to get down to the case level."