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From rain and snow to searing heat and everything in between, embedded IoT devices can face a difficult life in the great outdoors, and so can be designed with an encasement to physically protect them in their target operating environment. Several extremes to consider include temperatures, moisture, water exposure, shocks, and vibrations. At the same time, enclosures should provide access to onboard I/O ports, maintain wireless connectivity, and fulfill branding and aesthetic requirements.
In this blog post, we look at some standards for protecting against water and solids (known as ingress protection), and mechanical shocks and vibrations. We’ll then review some key considerations to protect your next embedded IoT device.
A well-known standard for ingress protection is the Ingress Protection (IP) ratings from the International Electrotechnical Commission (IEC). The IP ratings (see figure below) describe levels of protection against solids of different sizes and liquids at varying degrees of exposure.
|First Digit: Solids||Second Digit: Liquids|
|1 – Protected against object greater than 50 mm (like a hand)||1 – Protected against falling drops of water. Limited ingress allowed such that there is no interference with operation|
|2 – Protected against object greater than 12.5 mm (like a finger)||2 – Protected against failing drops of water with enclosure tilted 15” from vertical. Limited ingress allowed such that there is no interference with operation|
|3 – Protected against object greater than 2.5 mm (like a screwdriver)||3 – Protected against sprays of water up to 60” from vertical. Limited ingress allowed such that there is no interference with operation.|
|4 – Protected against object greater than 1 mm (like wire)||4 – Protected from water splashed from all directions. Limited ingress allowed such that there is no interference with operation.|
|5 – Dust Resistant. Limited ingress of dust allowed such that there is no interference with operation||5 – Protected against jets (30 kPa) of water. Limited ingress allowed such that there is no interference with operation|
|6 – Dust tight. No ingress of dust allowed.||6 – Protected against powerful jets (100 kPa) of water. Limited ingress allowed such that there is no interference with operation.|
|7 – Protected against immersion in water at a depth of 1 m for 30 min.|
|8 – Protected against submersion for long periods at a depth of 3 m.|
|9 – Protected against powerful, high temperature jets|
IP Ratings from IEC. Source: https://neuronicworks.com/blog/ip-ratings/
These IP ratings use a naming convention consisting of “IP” followed by two numbers indicating protection from solids of different sizes and liquids ranging from a few drops to complete submersion. For example, IP 67 means the device is dust-tight and protected against submersion in 1m of water for 30 minutes.
If a device only protects against one of the two elements (e.g., solids but not liquids), the non-protected element is marked with an “X”. For example, IP 6X means the device is dust tight but has no water ingress protection.
The code may also include the letter A, B, C, or D, indicating its protection against access to hazardous parts. For example, IP 6XC indicates the device protects against user access with a tool.
Another IP standard comes from the National Electrical Manufacturers Association (NEMA) used in North America for electrical enclosures. NEMA’s standard consists of several levels that cover access to hazardous parts and various environmental conditions. Like IEC’s standard, NEMA has several descriptive labels to become familiar with.
NEMA’s IP standard is arguably broader than the IEC’s, as it covers additional use cases such as submersion in oil, corrosion resistance, and safe usage around gasses.
You’ll commonly see either of the two standards listed in technical datasheets for IoT devices or enclosures suited for dusty and/or wet environments.
Mechanical Shock and Vibration
An IoT device can also be subjected to shock and vibration during shipping and transport and while in service.
Testing involves subjecting the device or enclosure to various g-forces, as well as vibrations at different frequencies and durations. Below are some common standards for mechanical shock and vibration certification:
- International Safe Transit Association (ISTA) defines detailed test procedures for pre-shipment distribution and packaging. They currently define five drop tests to simulate product performance in transit and within packaging across a variety of conditions, drop heights, and vibration levels.
- American Society for Testing and Materials (formerly ASTM International) is an international organization that develops technical standards for materials, products, systems, and services. Their D3332-99 standard defines test methods to determine the mechanical shock fragility of both shipping containers and products.
- International Organization for Standardization (ISO) is an international organization that develops consensus-based and relevant international standards. Their ISO 8568:2007 standard defines specifications for shock testing machines (e.g., to test IoT device enclosures).
- US Military Standard (MIL STD) is used in both military and commercial applications. The MIL-STD-810 standard defines requirements for materials to withstand shocks in handling, transportation, and in-service, as well as fragility levels for packaging and mounting configurations. An example of a MIL-STD-810G-compliant device is the Sierra Wireless FX30 which incorporates our Qualcomm 9206 LTE IoT Modem and is compatible with their Octave IoT framework.
When developing devices for mission-critical scenarios (e.g., military), standards like these are often hard requirements. Developers must identify such requirements and their protection levels before the project starts, as this will dictate factors like enclosure design, material choice, mounting options, etc.
Some of our recent guest blogs showcase our LTE IoT modems operating in less than ideal environments.
The Tattle System by North Star (shown in figure above) monitors agricultural assets and uses our Qualcomm 9205 LTE modem and Qualcomm 9207 LTE modem for connectivity. The Tattle System has an IP54 rating, operating range of -40 to +60 °C, and is certified for use in hazardous environments.
Another example is the Sensoneo Digital Waste Management Platform. The platform’s Smart Sensor (shown in figure below) is installed in waste bins to measure and report waste levels using an embedded Qualcomm 9206 LTE IoT Modem for connectivity.
The sensor’s enclosure is made from polyamide with optical fibers, is shock resistant, and IP69-compliant. This makes it well suited for the harsh environment and handling of commercial-duty waste bins.
Key Considerations for Protecting Devices
The examples above show that our processors can successfully operate in challenging environments given the right protection. But such performance doesn’t happen by chance. Developers should plan for physical protection from the start of the project. Here are a few key considerations:
- Identify all standards to which your organization or customer should adhere
- Look for manufacturers that build enclosures to specific standards (e.g., a NEMA-compliant enclosure)
- Minimize the number of seams required to seal an enclosure
- Use quality gaskets and O-rings to prevent leakage through seams and fasteners
- Calculate/adhere to fastener torque recommendations to ensure even pressure distribution (e.g., across seals)
- Choose corrosion-resistant materials like stainless steel when applicable
- Build heat dissipation features into the enclosure design. Use heat-resistant materials like aluminum and incorporate heat sink-like fins to increase the surface area.
- Mount circuit boards inside the enclosure with isolators to reduce the amount of shock transmitted to the electronics
- Choose material thicknesses that prevent flex. This prevents forces from straining the circuit board.
- Avoid directly exposing your circuit board’s IO ports through the enclosure. Wire them to separate IO port connectors mounted on the enclosure to help prevent damage (e.g., from forces applied to external cables).
- Ensure the enclosure’s internal space is sufficient to accommodate internal cables while complying with their minimum bend allowances.
- Plan for branding and aesthetic requirements that may affect the enclosure’s protection ability.
Protect Your Next Device
When your device is ready to ship, be sure to list all standards that your product complies within your technical specifications and other documentation. It’s a common requirement that not only bolsters customer confidence but allows you to proudly state the high standards by which your device is protected!
For additional information about physical device protection, check out the following websites:
- IP Ratings in Product Design
- Electrotechnology enclosure testing: IEC 60529 and NEMA
- Packaging Embedded Systems
Also be sure to check out our Projects page, where you can see a broad range of examples showing our hardware solutions in action.
Qualcomm 9205 LTE IoT Modem, Qualcomm 9206 LTE IoT Modem, and Qualcomm 9207 LTE IoT Modem are products of Qualcomm Technologies, Inc., and/or its subsidiaries.