Model UI Data Sheet

Model UI - IR Drop Sensor

Typical Application:

Conduct instant off potential measurements on all underground structures including:
- Pipelines
- Aboveground storage tank bottoms
- Underground storage tanks
Measure relative changes in electrolyte resistivity.

Featuring:

Can be used with both sacrificial and impressed current cathodic protection systems
No interrupters needed at the rectifier
Small sensor area will not distort cathodic protection current field

Description:

The Model UI probe is designed to come to the same potential as the steel used for buried structures such as pipelines and tanks. An important feature of this sensor is that the exposed area of the probe is similar to that of a holiday in the coating on the structure. This prevents any distortion of the CP current field. Probes with a large exposed area or separate coupons electrically tied to the structure require significant amounts of current to polarize them to the structure potential. In the case of a sacrificial system where anode output is fixed by soil resistivity, this large current demand can adversely affect cathodic protection of the structure.

Model UI Instant Off Sensors are fitted to EDI underground references at time of manufacture. The reference should be installed 1 to 3 feet (¼ to 1 m) from the structure and surrounded with the same backfill that surrounds the structure. The probe should be pushed into the backfill so that it is within 6 inches (15 cm) of the reference. At the test station, a shorting bar is placed between the sensor terminal and the structure terminal. Normal potential readings are made between the reference and sensor terminals with the shorting bar connected. The instant off potential is measured between the reference and sensor terminals as the shorting bar is disconnected.