What’s the maximum cable length I can have when using a datalogger to read 4-20mA titanium pressure transducers?

Approximately 240 meters or 800 feet. The datalogger supplies 12 volts, and the transducer requires at least 8 volts. The standard cable used with the 4-20mA transducer has 22 gauge wire so voltage drops about 0.6 volts per 1000 feet.