How do I know what barriers are compatible with which sensors?

You can find a compatible Zener barrier and galvanic isolator on the sensor data sheet to select from. This will typically be guided by the onsite grounding policy.  You will need one barrier per circuit so 1 sensor : 1 barrier or 1 sensor : 2 barriers if using with a temperature sensor. Barriers are used to protect the circuit in ATEX environments.