When a steel tank is installed with a galvanic CP system attached, the tank gauges are usually connected through a riser with a dielectric bushing. What is the purpose of that?

When a steel tank is installed with a galvanic CP system attached, the tank gauges are usually connected through a riser with a dielectric bushing. What is the purpose of that?

• A. To prevent static discharge
• B. To minimize effects of noise
• C. To electrically isolate the tank from the tank gauge
• D. To prevent water intrusion in the tank

Answer: (C)

In a galvanic cathodic protection system, you want to keep the protective electrical current confined to the tank structure and not let it flow through measurement devices. The dielectric bushing in the riser acts as an insulating barrier between the tank metal and the tank gauge wiring. This electrical isolation prevents CP current from taking a path through the gauge, which could distort readings or create unintended current paths that compromise both the accuracy of the level measurement and the effectiveness of the protection system. So the purpose is to electrically isolate the tank from the tank gauge.

In a galvanic cathodic protection system, you want to keep the protective electrical current confined to the tank structure and not let it flow through measurement devices. The dielectric bushing in the riser acts as an insulating barrier between the tank metal and the tank gauge wiring. This electrical isolation prevents CP current from taking a path through the gauge, which could distort readings or create unintended current paths that compromise both the accuracy of the level measurement and the effectiveness of the protection system. So the purpose is to electrically isolate the tank from the tank gauge.