Bosch BME280 Mounting Instructions page 13

Bosch Sensortec | HSMI BME280
Figure 3: Shielding of the sensor from heat sources by means of a barrier within the housing minimizes heat
convection (top left). Small dead volume is realized by barriers in the housing combined with a large aperture (top
middle). Placement of the sensor with a defined air flow over the sensor minimizes the temperature deviations
between sensor and the environment (top right). It is not recommended to have a large dead volume if the air flow is
not defined and doesn't strike the sensor (bottom left). Small aperture compared to the dead volume doesn't ensure
an accurate air circulation (bottom middle). Large dead volumes have to be minimized (bottom right).
Wrong placement can also lead to inaccurate measurement of the relative humidity due to delayed
response time. Therefore some simple guidelines will accomplish a fast response time:
 Placement of the sensor as close as possible to the environmental air
 Single opening is not the optimum solution compared to a defined air flow over the sensor
 Dead volume must be minimized
 Large aperture is preferred
 Use of port protection will reduce the response time
 Usage of material within the dead volume which is susceptible to moisture has to be avoided
 Vent hole of application and air flow have same direction
 Air flow (breath) must be directed along the z-axis straight at the sensor lid
Document number BST-BME280-HS006-00 | May 2018
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parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
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