Si7021 & SHT21 vs dust

Thread Starter

Georg_B

Joined Apr 18, 2022
13
Hello!

I've already used Si7021 sensors without problems. Now I've got SHT21. As you can see on the picture, no protective cover on the SHT21 sensor. Is it problem if I'm using the sensor in dusty enviroment? Is the dust can affect the accuracy? If yes, how can I protect the sensor from dust? I'm not working in a clean room, so dust can touch the sensor while I'm working with it, not only in the final placement.

I absolutly don't know how this sensor works, what is inside the little window.

Thank you!
 

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nsaspook

Joined Aug 27, 2009
13,567
https://www.ti.com/lit/an/snaa346/snaa346.pdf
Humidity sensors are unique electronic components because their sensing elements must be exposed to the environment in order to sense the environment’s humidity level. Whether their sensing elements are based on resistive or capacitive technology, the sensors’ accuracy could potentially degrade or damage could occur to the sensor itself if they are not properly protected. For this reason, there are different protective covers available for humidity sensing components.
..
1.2 Permanent Cover Humidity Sensors A permanent cover is made of hydrophobic microporous PTFE membrane to protect against water and dust according to IP67 specification, and is designed to stay on the package over the product lifetime. This protective cover has a filtration of up to 99.99% efficiency filtering particle sizes down to 100nm. In addition to being water and dust proof per IP67, this PTFE material has extremely high-durability and low-friction to repel water, condensation droplets and debris, while maintaining sensor response time, making it most suitable for outdoor use and rugged environment applications. Figure 1-5 depicts a humidity sensor with a permanent protective cover, the HDC2022, which is pin- and software- compatible with HDC2080 and HDC2021. Most applications can use non-protective cover humidity sensors because of its robust polymer sensing element. Also, all these sensors are based on the same core and inherently offer some of the lowest power consumption with high and consistent accuracy in the market. If an assembly line cannot provide special flow for standard humidity sensors or a sealed humidity sensing module is desired, then a removable protective cover humidity sensor, like the HDC2021 would be an excellent option. For outdoor use or harsh environment usage, where condensation is likely to occur or volatile organic compounds (VOCs) may be present, the HDC2022 would be the best choice.
I've used the BME280 on boards with no special considerations other that what's normal for electronics.
https://forum.allaboutcircuits.com/...tter-for-this-application.193257/post-1823342
https://www.bosch-sensortec.com/products/environmental-sensors/humidity-sensors-bme280/
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27.24RH from the BME280

Is your sensor directly exposed or in a hazardous environment? If so then I would use a sensor with the extra protective cover but that also means the rest of the electronics will also need some added level of protection from that.
 
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Thread Starter

Georg_B

Joined Apr 18, 2022
13
Is your sensor directly exposed or in a hazardous environment? If so then I would use a sensor with the extra protective cover but that also means the rest of the electronics will also need some added level of protection from that.
Lots of dust (more than normal outside enviroment), it's a grain silo. Interestingly, most of the humidity sensors don't have protective filter. Looks like I have to create protection, maybe some thin wool felt. Enviromental sensor, speed is not critical.
 

nsaspook

Joined Aug 27, 2009
13,567
Lots of dust (more than normal outside enviroment), it's a grain silo. Interestingly, most of the humidity sensors don't have protective filter. Looks like I have to create protection, maybe some thin wool felt. Enviromental sensor, speed is not critical.
Yes, a grain silo is a hazardous dust environment, be careful.
 
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