8.6.1 Freezing or High Temperature Conditions
Although precautions can be taken, placing an AquaVent in a situation where the water may freeze solid can permanently damage the sensor.
AquaVent Vented Water Level Datalogger installation in locations that may be at risk of freezing, is not recommended without taking precautions. When water freezes it expands approximately 9% by volume. A 9% expansion can equate to extreme pressure. Therefore, solid freezing has the potential to damage the pressure transducer, which is rated to withstand up to 200% of its depth fluctuation range. As such, care should be taken when choosing the appropriate pressure transducer range for your application.
If monitoring shallow water bodies or groundwater zones susceptible to freezing, the easiest way to avoid transducer damage is to lower the transducer to a point in the water column below the frost line or ice formation depth. In water bodies such as shallow streams, wetlands or ponds where freezing may penetrate to the bottom, install the AquaVent in a vented stilling well imbedded into the bottom of the water body beyond the frost line.
In cases where the above noted precautions cannot be taken and the AquaVent must be installed in the freezing zone, it is recommended that the AquaVent be placed inside a thick membrane balloon filled with a non-toxic, non- corrosive anti-freeze solution and sealed. Place the balloon in a section of perforated, 1.25" (30 mm) ID pipe and install the AquaVent in the monitored water. The antifreeze solution will protect the AquaVent from ice expansion at the pressure transducer, yet transmit any pressure and temperature fluctuations that occur. However, it should be noted that even if these precautions are taken, there is still the risk that placing an AquaVent in a situation where the water may freeze solid can permanently damage the sensor.
Please note that a similar installation protection can be used when the AquaVent is monitoring liquids which are incompatible with its wetted materials.
The operating temperature range for the AquaVent is -20° to 80°C (-4° to 180°F). At the opposite end of the thermal scale, exposing the AquaVent to temperatures beyond 80°C may damage the thermistor and otherwise affect the AquaVent.