I’d take a look at this topic…
If you’re going to put any type of sensor in a freezer at -50 then you;re going to have to be careful with the sensor to ensure that it doesn’t suffer from ice damage. There is a waterproof version of the DS18B20 that is the one I’d choose.
As I said earlier, i wouldn’t use the DHT range of sensors for your humidity sensing application. They are inaccurate and slow, and difficult to use reliably in an industrial situation.
Moving to an I2C sensor such as the SHT range would be my preferred sensor and it may remove the need to replace your cabling.
I’ve been running a waterproof SHT30 in an outdoor weather station for a few years and it’s proven very reliable. That would be my choice of sensor for the pig farm environment that you’ve described.
If you are going to re-cable the current situation then I’d probably avoid a twisted pair cable, or at least do some tests first. If you do relocate your sensor to a central location then you could use multiple pairs bonded together for each sensor, which may help.
Pete.