> For the complete documentation index, see [llms.txt](https://3dpaws.comet.ucar.edu/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://3dpaws.comet.ucar.edu/station-maintenance-and-operations/sensor-lifecycle-planning.md). # Sensor Lifecycle Planning Guidance for planning sensor replacement, rotation, and long-term maintenance of 3D-PAWS stations. ### Overview Environmental sensors and mechanical components change over time because of aging, wear, and exposure to field conditions. Sensor lifecycle planning helps maintain data quality and station reliability by identifying components that should be inspected, verified, or replaced before they cause extended station downtime or measurement problems. Replacement intervals should be treated as **planning guidance rather than fixed expiration dates**. Actual service life depends on the component, environmental exposure, maintenance history, and observed performance. *** #### Why Sensor Lifecycle Planning Is Important Environmental sensors and station components are continuously exposed to conditions such as: * humidity and condensation * temperature cycling * dust and pollution * salt exposure * insects and biological contamination * ultraviolet radiation * mechanical wear Routine cleaning and inspection help maintain sensor performance, but they do not prevent long-term aging, drift, or mechanical wear. Planned replacement allows components to be removed, inspected, cleaned, and verified while reducing the risk of unexpected failure or undetected measurement problems. *** #### Environmental Exposure Replacement intervals depend strongly on the conditions at the deployment site. For planning purposes, 3D-PAWS deployments can be considered **benign** or **harsh** environments. **Benign Environments** Typical characteristics include: * dry or semi-arid climates * inland locations away from salt spray * relatively low dust or pollution * limited fog, dew, or condensation **Harsh Environments** Typical characteristics include: * coastal or marine environments * tropical or persistently humid climates * frequent fog, dew, or condensation * dusty agricultural environments * polluted environments Stations in harsh environments may require more frequent inspection, maintenance, and component replacement. {% hint style="info" %} These categories are intended for maintenance planning. Local conditions and observed sensor performance should always be considered when determining replacement intervals. {% endhint %} *** #### Radiation Shield Sensor Set The radiation shield typically contains the air temperature, relative humidity, and pressure sensors. These sensors are commonly replaced together as a set to simplify field maintenance and verification. | Sensor | Typical Replacement Interval | Notes | | -------------------------------------------- | ---------------------------- | -------------------------------------------------- | | **SHT31D (Relative Humidity / Temperature)** | 1–2 years | Interval driven primarily by humidity sensor aging | | **MCP9808 (Temperature)** | 1–2 years | Rotated with the radiation shield sensor set | | **BMP390 (Pressure)** | 1–2 years | Rotated with the radiation shield sensor set | As general planning guidance: * **Benign environments:** replace the sensor set approximately every **2 years** * **Harsh environments:** replace the sensor set approximately every **1–1.5 years** Replacing the sensors together simplifies field operations and allows the complete sensor set to be inspected and verified after removal. *** #### Wind and Precipitation Sensors Wind and precipitation instruments contain moving mechanical components and may experience wear over time. | Instrument | Typical Replacement Interval | Primary Consideration | | -------------- | ---------------------------- | ------------------------------------ | | **Wind Vane** | 2–3 years | Mechanical bearing wear | | **Anemometer** | 2–3 years | Wear in rotating components | | **Rain Gauge** | 1–2 years | Mechanical condition and calibration | For wind sensors, general planning guidance is: * **Benign environments:** approximately every **3 years** * **Harsh environments:** approximately every **1.5–2 years** Rain gauges should be inspected regularly and periodically verified or recalibrated to ensure accurate precipitation measurements. {% hint style="info" %} A component does not necessarily need to remain in service until its planned replacement interval. Replace or remove a sensor earlier if inspection, verification, or station data indicate abnormal performance. {% endhint %} *** #### Optional Sensors Optional environmental sensors may have different service lives depending on their sensing technology and deployment environment. Follow manufacturer recommendations when available and consider: * environmental exposure * observed sensor performance * calibration or verification requirements * physical condition * maintenance history {% hint style="info" %} Soil sensors often require time after installation for the surrounding soil to settle and for measurements to stabilize. Initial stabilization should not automatically be interpreted as sensor aging or failure. {% endhint %} *** #### Sensor Rotation Where practical, maintain verified spare sensors or assemblies that can be exchanged during scheduled maintenance visits. When rotating a sensor: 1. Install a verified replacement sensor or assembly. 2. Record the replacement in the station maintenance and asset records. 3. Return the removed component for inspection, cleaning, and testing. 4. Repair or recalibrate the component if necessary. 5. Return verified components to the spare inventory for future use. This approach reduces field time and allows sensor evaluation to be performed under controlled conditions. *** #### Replace Components Earlier When Needed Planned replacement intervals should not override evidence that a component is failing or degrading. Consider earlier replacement when: * observations become unexpectedly noisy or unstable * measurements show persistent or unexplained bias * data become intermittent * mechanical components bind or no longer move freely * connectors, cables, or housings show significant deterioration * moisture, corrosion, or contamination affects the component * verification or calibration indicates unacceptable performance See **Troubleshooting** when abnormal station behavior is first identified. *** #### Record Component Changes Document sensor and component replacements as part of the station's operational history. Record: * station ID * component or sensor * installation date * removal date * reason for replacement * condition when removed * verification or calibration results, when applicable * replacement component information → [**Asset Management**](/station-maintenance-and-operations/asset-management.md) → [**Station Metadata**](/deploying-3d-paws/station-metadata.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. 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