There’s a lot more to consider than just the temperature rating when choosing a handheld mobile computer or tablet or even an RFID reader, barcode scanner, printer, or wearable for use in cold chains (or cold weather).
Mobility experts have said it before, but marketing and sales materials such as spec sheets can be too simplistic or too listicle. They may disclose every device component and rating, but they don’t necessarily provide context about why those components or ratings matter. As a result, it can be easy to miscalculate how well those specs translate to your particular use case.
For example, almost every mobile computer or tablet spec sheet will list the device’s operating temperature and storage temperature, along with other environmental tolerances, such as humidity and thermal shock. However, what most spec sheets won’t tell you is that temperature rating alone doesn’t automatically make a mobile computer or tablet suitable for regular use in those temperature ranges. This is particularly true for devices used in supply chain environments where workers may be moving between warmer and colder environments multiple times a day.
Let’s say your workers are constantly going in and out of cold storage units or moving between a cold yard or loading dock and a warmer warehouse space. Every time a rapid temperature transition occurs, there’s a risk of condensation building on and in the device they’re using, which can impair their device’s performance and their personal productivity. When that condensation builds up and the display starts fogging, your workers will struggle to see the task list or map. They may even find it difficult to scan a barcode since the scanner may not be able to see the barcode through a fogged window.
Some workers may find themselves constantly trying to wipe off the external condensation from the display, which becomes a distraction. Others may just wait until it clears up, which causes a delay. Then there’s the possibility that condensation builds up inside the device, fogging the screen or the scanner window. In a worst-case scenario, internal condensation could damage device parts, forcing the device out of service for repairs. Even if you have backup devices available to workers, they must still stop to swap out the device. That could completely disrupt the workflow.
Along those same lines, using the wrong device in cold environments could impact display refresh rates and reduce battery cycles. Regardless of whether the display fogs, cold temperatures will reduce the screen refresh rate if not properly mitigated with a heater. This will quickly become frustrating to the user. It will also be frustrating if they must constantly swap out batteries because they don’t last a full shift (because they got too cold.)
That’s why it’s so important you ask about the impact of certain device specifications on your potential use case and ask about specs that may be missing from spec sheets. Never assume that an operating or storage temperature rating alone makes a device (or its peripherals) suitable for use in cold chain or cold weather environments.
That said, let me call out a few things you should be looking for when choosing a handheld mobile computer, tablet or even vehicle-mounted computer that will be used in freezers, freezing cold yards or other cold environments:
- Seal Rating – This is commonly known as the Ingress Protection (IP) rating. You want to look for at least an IP65 rating, though IP66 or IP67 may be better depending on your environment. You’ll want the device to be as tightly sealed as possible, to include I/O ports, to prevent moisture from getting inside and posing a risk of condensation during temperature swings.
- Integrated Heaters – Even if a mobile computer or tablet is rated for an extreme operating temperature range, the only way it’s going to truly be usable in settings where there will be quick temperature changes (i.e., moving between coolers and a hot warehouse floor) is if it also has built-in heating elements. These are designed to prevent frost and condensation build-up on the screen and scanner window, as well as inside the device around key components like the connectors, board, battery and displays. Heaters used to be almost exclusive to vehicle-mounted computers, but they are increasingly found in handheld mobile computers and rugged tablets as well. Just be sure to ask when and how the heaters work. Do they automatically kick on and regulate or will they need some sort of manual intervention to run properly? Also confirm whether the heater works in all use cases or only when the device is mounted. For example, with the Zebra ET6x Series freezer-ready rugged tablets, the heater only kicks in when the device is locked into a forklift mount. The same goes for the keyboard’s heater.
- Swappable batteries – Since not all cold-rated devices are going to come with heater options, it’s important that you choose devices with warm or hot swappable battery options. That way, when the cold temperature ultimately impacts the battery’s cycle, your workers can quickly power back up and keep moving. Also, if the device will be used in freezing temperatures, consider choosing one with a dedicated freezer battery. Standard mobile batteries shut off at -20 C, whereas freezer batteries don’t have that limitation.
- Device design – Many cold and freezer-rated devices will have unique features that make them more resistant to extreme temperatures. For example, they may feature optically bonded Gorilla Glass displays, flat surfaces that deter ice buildup, drainage channels that remove condensation before ice can build up, and special materials that can withstand drops in freezing environments. (Many plastics can get brittle in freezing temps and experience damage when dropped.)
- Peripheral ratings – Even if your device can withstand the elements, your workers will get slowed down if their keyboard or cables ice over. As condensation forms or melting ice drips down into the keyboard area when users leave the freezer, keys can freeze when users return to the freezer, making it impossible to enter or retrieve needed data. So, depending on the use case, you may need a heated keyboard to attach to the device (especially a vehicle-mounted tablet) or freezer-rated cables to connect a standalone barcode scanner to a mobile computer. You should also ensure headsets and other wearables can tolerate the same conditions.
- Glove Compatibility – If the device is going to be used in cold environments, whoever is using the device will likely be wearing gloves. Make sure the touchscreen (and the buttons in general) are glove compatible. Look for resistive touchscreens, as they work better with thicker gloves than capacitive touchscreens or equip your workers with touchscreen-compatible gloves that improve the user experience. It’s also important to confirm if devices and accessories are “freezer rated” or “cold ready” and whether they are “condensation free” or “condensation resistant.” At Zebra, we articulate these differences on our hard copy and online spec sheets, as well as in our cold chain mobility guide and tablet selector tool. However, not every vendor will. So, always ask.
What About Other Types of Mobile Devices?
Now that you know what makes a mobile computer or tablet suitable for cold environment use, you may be wondering about other types of devices. Does the same advice apply? Well, I asked some of my colleagues what is most important to consider when it comes to mobile printers, barcode scanners, and RFID readers. This is what they said:
Though many wearable mobile computers may be cold rated, the Zebra WT6300 is the only mobile computer in its class right now rated for freezer use. That’s because it has a freezer-rated battery, along with a drop rating that confirms it will survive in the coldest temps. (Remember those brittle plastics?) If you don’t need a freezer-rated wearable, but you do want a cold-rated one, look for models with glove-optimized touchscreens, a higher IP rating and a wide operating and storage temperature range.
In addition to choosing a printer with a wide operating and storage temperature range, there are a few additional features that would be of benefit in cold environments. For example, it’s best to choose a mobile printer with a cold temperature compensation mode, as it balances and optimizes print speeds to allow for better print performance at lower temperatures. With some mobile printers, you’ll see a drop in print quality as temperatures drop. However, models with a cold temperature compensation mode experience will deliver consistently sharp print quality, even in cold temperatures.
Additionally, IP rating matters here, though IP54 is often considered acceptable for most mobile printers used in cold settings. If you feel you need an IP65 mobile printer, you may need to add an exoskeleton accessory (which is easy to find/attach).
Of course, choose a mobile printer that has large buttons since users will be wearing gloves. This will increase accuracy and decrease user frustration. Also opt for mobile printers with large, easy to read color displays. Beyond that, most of the recommended features would be similar to what’s recommended in typical warehousing, transportation, logistics and field environments: the ability to upgrade firmware on the go, high-capacity batteries, high drop and shock ratings, remote management tools, etc.
One more thing: You will need to use cold-rated barcode and RFID labels for printing because temperature shock and condensation are an issue for these supplies as well. There are certain labels that use a unique all-temperature adhesive that can remain adhered in cold temperatures ranging from as low as -40°F (-40°C) to -75°F (-59°C) and are able to be stuck to surfaces in cold temperatures ranging from -20°F (-28.9°C) to -40°F (-40°C). There are also labels that can help you confirm temperature-sensitive goods have stayed within the acceptable range from the point of manufacture to the point of sale (retail) or point of administration (pharmaceutical). You can learn more about those here.
There are a few handheld RFID readers and RFID sleds that are considered ultra-rugged and ready for cold chain use, mainly because of their extreme operating and storage temperature ranges, non-condensing humidity rating, and IP rating. If you choose to use these RFID readers, be sure they’re paired with mobile computers that are also rated for use in extreme operating environments. Otherwise, the mobile computer may not perform as expected and hinder your ability to collect RFID tag data. That said, depending on your use case, you may be better served by fixed RFID readers that were made specifically for cold chain use cases and freezer door use. We’ve been working with one of the largest quick service restaurants (QSR) chains in the world, and one of its largest suppliers of frozen ingredients, to scale a cold chain RFID system that can be used for track and trace, inventory management and more. So, if you need RFID capabilities in cold chain (or even just cold warehouse) environments, it’s best to consult with an RFID solution engineer who specializes in your type of application.
There aren’t as many sensitive computing components in standalone barcode scanners as there are in mobile computers and tablets, so the primary considerations here are the operating and storage temperature ranges, the IP (seal) rating and the cable rating. However, there are holders available on the market that are designed to eliminate the risk of fogging and freezing-related issues while not in use. If that’s a concern you have, you can learn more about them here.
This blog is contributed by Zebra Technologies.