We do not have an IPI68 certificate for the model 4500SR.
IP68 is :
6 = dust tight, no ingress of dust
8 = Immersion beyond 1 meter, the equipment is suitable for continuous immersion in water.
The model 4500SSR is a vibrating wire piezometer with strain relief cable, is designed to be installed in applications to measure water pressure from 350KPA up to 20MPA depending on the range specified when we manufacture it.
It is a sealed sensor and water intrusion into the sensor is not a problem unless the head of water, or the pressure that the sensor is subjected to is 2x greater than the specified range.
The 4500 series is specifically designed to be installed in water at depths greater than the 3 meters required in the IP testing, so the 4500 piezometer would meet IP68