Although the LV-MaxSonar-EZ and XL-MaxSonar-EZ sensors were designed for "protected indoor environments", the LV-MaxSonar-EZ and XL-MaxSonar-EZ sensors have been used outdoors in very rugged environments.
The link below sports a very good discussion on the MaxSonar-EZ1. http://www.cocoontech.com/index.php?showtopic=4419.
It also shows an easy to build housing that keeps the sensor "protected" while in operation, where a plastic PVC housing and some very thin foam is used on the sensor face.
Here the sensor is used in the air above the water line to measure the draft of a ship.
This link below shows how the sensor was used to measure salt in a water softener. http://www.cocoontech.com/index.php?showtopic=4666
And this link below shows the High-Lighter where a MaxSonar-EZ1 reads a trampoline in operation. The higher the jump the larger the flame burning in the display. http://screwdecaf.cx/high-lighter.html.
We have not tested any of these housings for the LV-MaxSonar-EZ and XL‑MaxSonar‑EZ sensors. For users desiring to use our sensors this way, care should be taken to protect the transducer from moisture including dew and condensation.