In a galvanic CP installation, what is the purpose of using a dielectric bushing with the tank gauge riser?

In a galvanic CP installation, what is the purpose of using a dielectric bushing with the tank gauge riser?

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

Answer: (C)

In galvanic CP systems, controlling where currents can travel is essential to keep the protection effective. A dielectric bushing in the tank gauge riser creates an electrical barrier between the tank and the gauge hardware. This means the tank and the gauge are electrically insulated from each other, so the CP current cannot use the gauge path as part of the circuit. As a result, the gauge can measure the tank’s true potential relative to the soil without interference from current flowing through the gauge connection, and the protection on the tank remains consistent. The other ideas don’t fit this primary role. It’s not about preventing static discharge, reducing electrical noise, or preventing water intrusion—the dielectric bushing’s purpose here is to maintain electrical isolation between the tank and the gauge.

In galvanic CP systems, controlling where currents can travel is essential to keep the protection effective. A dielectric bushing in the tank gauge riser creates an electrical barrier between the tank and the gauge hardware. This means the tank and the gauge are electrically insulated from each other, so the CP current cannot use the gauge path as part of the circuit. As a result, the gauge can measure the tank’s true potential relative to the soil without interference from current flowing through the gauge connection, and the protection on the tank remains consistent.

The other ideas don’t fit this primary role. It’s not about preventing static discharge, reducing electrical noise, or preventing water intrusion—the dielectric bushing’s purpose here is to maintain electrical isolation between the tank and the gauge.