SHT40 Breakout for high RH% environment

General project help for Adafruit customers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
AndrewPak
 
Posts: 2
Joined: Fri Jan 27, 2023 5:01 pm

SHT40 Breakout for high RH% environment

Post by AndrewPak »

I ordered an SHT40 to monitor and regulate humidity in an 80-89% humidity grow environment. I'm concerned about sticking the entire breakout board in the grow space. The constant high humidity without any breaks is probably going to corrode the components on the board. I've been thinking about screwing it onto a wall of a waterproof PCB enclosure and drilling an extra hole where the sensor can be exposed to the air. How would make sure that none of the high humidity air makes it through the hole? Is it safe to use silicone caulking or a hot glue gun to seal the gaps?

User avatar
mikeysklar
 
Posts: 13824
Joined: Mon Aug 01, 2016 8:10 pm

Re: SHT40 Breakout for high RH% environment

Post by mikeysklar »

The SHT40 datasheet mentions a littlebit about their own protective design.
E968F98A-B8AC-4403-8370-B92E287F0927.jpeg
E968F98A-B8AC-4403-8370-B92E287F0927.jpeg (650.7 KiB) Viewed 136 times
https://cdn-learn.adafruit.com/assets/a ... 1673387912

It also gets into recommended operating conditions in which > 80% will start to skew humidity readings.
2.3 Recommended Operating Conditions
Figure 13. SHT45 typical and maximal temperature accuracy.
The sensor shows best performance when operated within the recommended normal temperature and humidity range of 5 °C ... 60 °C and 20 %RH ... 80 %RH, respectively. Long term exposure to conditions outside recommended normal range, especially at high relative humidity, may temporarily offset the RH signal (e.g. +3 %RH after 60 h at >80 %RH). After returning into the recommended normal temperature and humidity range the sensor will recover to within specifications by itself. Prolonged exposure to extreme conditions may accelerate ageing.

User avatar
AndrewPak
 
Posts: 2
Joined: Fri Jan 27, 2023 5:01 pm

Re: SHT40 Breakout for high RH% environment

Post by AndrewPak »

Thanks. It's my understanding that using conformal coating is tricky and requires proper baking to get it right. How could I do this at home? Now, I don't need this thing to give me accurate readings for years. I'm happy to replace any RH sensor over time, but I'm more concerned about the board not lasting very long due to the humidity.

The SHT4x have a programmable heater that can supposedly keep it functioning well in condensing environments. And I'm not too worried about drift of 3%. My main concern is keeping the board intact. Can I mount the board with the sensor to the outer wall of my environment and then make a hole right where the sensor is? And then make a seal around it with some kind of epoxy?

User avatar
mikeysklar
 
Posts: 13824
Joined: Mon Aug 01, 2016 8:10 pm

Re: SHT40 Breakout for high RH% environment

Post by mikeysklar »

Only exposing the sensor to the inner environment while mounting the board externally. You can probably make use of the air gap this board features around the sensor itself to help further enclose the sensor with some 1/4" tubing maybe?
sht40.jpg
sht40.jpg (230.61 KiB) Viewed 124 times

User avatar
adafruit2
 
Posts: 22111
Joined: Fri Mar 11, 2005 7:36 pm

Re: SHT40 Breakout for high RH% environment

Post by adafruit2 »

this sensor has a PTFE cover
https://www.adafruit.com/product/2857

Locked
Please be positive and constructive with your questions and comments.

Return to “General Project help”