Olpas guarantees sensor performance down to -10°C. However, this is not a 'hard' limit but a performance boundary. Sensors operate well below this temperature at comparable accuracy, but small temperature dependent effects might come up in some cases. Below -20°C operation is not recommended.
For salt or brackish water such low temperatures can be obtained ice-free without any risk of sensor damage. For sensors operated in wastewater treatment plants, ice formation is not an issue as water temperature is kept above 0°C continuously.
However fresh water, especially slow moving water bodies, can form ice on the surface or fully freeze. Sensors are most often damaged in the following way:
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Partially submerged sensor risk compression forces on the enclosure during ice formation and potential deformation.
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Fully submerged sensors are mostly vulnerable at the water surface, where the cable is in contact with air and water. Ice mostly attaches to cables and sensor mounts and drastically increases mechanical loading.
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For regions with mild temperatures (min -5°C, -10°C for short time periods ) it is sufficient to install sensors under the water surface. Provide cable protection (cable feed-throughs) where necessary.
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For -10°C to -20°C during extended periods of time: considering removing sensors for the winter period or monitor sensor temperature and ice loading during the season.
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For measurements below packed ice it is recommended to provide battery power and datalogging submerged in order to remove the effect of ice transport entirely. Contact support@olpas.tech for power and datalogging solutions.