GAS STATION
A typical gasoline station has a storage capacity of 30,000 to 40,000 gallons in underground tanks. In the past, these tanks were sometimes subject to spills from overfilling of the tanks and to leaks caused by corrosion. Today, station owners have taken several important steps to reduce these risks.
- Over-fill Protection Devices |
- Cathodic Corrosion Prevention |
- New Tank Materials/Coatings |
- Catchment Basins |
- Leak Detection Devices
Over-fill Protection Devices
Sensors and alarms let the operator know when the tank is getting full, and automatic shut-off switches stop pumping fuel into the tank before the tank completely fills.
- An electronic alarm - triggered by a floating sensor within the tank - activates a warning light and/or sound to tell the operator when the tank reaches 90 percent capacity (the target fill level).
- As a backup, a so-called flapper valve attached to the delivery pipe uses a floating arm to trigger a shut-off valve when the product in the tank reaches a certain level - similar to the shutoff device in a toilet.
- Finally, a ball float valve on the vent pipe - activated by the rising product - prevents vapor from escaping, essentially providing a vapor buffer within the tank to prevent more product from entering.
- Over-fill Protection Devices |
- Cathodic Corrosion Prevention |
- New Tank Materials/Coatings |
- Catchment Basins |
- Leak Detection Devices
Cathodic Corrosion Prevention
Corrosion of metal storage tanks and pipelines is essentially caused by steel slowly breaking down (rusting) when in contact with moist air or ground. This is an electrochemical process: If the environment has a positive electrical charge - meaning it "wants" electrons to return to electromagnetic balance -- electrons from the steel are drawn off, breaking up the steel at the molecular level, which is visible as rust. Applying a small positive electrical charge to the tank helps prevents electrons in the steel from being drawn off.
- Over-fill Protection Devices |
- Cathodic Corrosion Prevention |
- New Tank Materials/Coatings |
- Catchment Basins |
- Leak Detection Devices
New Tank Materials/Coatings
Underground moisture can corrode steel tanks. New fiberglass tanks and steel tanks coated with fiberglass or other durable coatings help prevent corrosion. The same high-tech coatings and linings also protect the nation's pipelines and above-ground storage tanks.
- Over-fill Protection Devices |
- Cathodic Corrosion Prevention |
- New Tank Materials/Coatings |
- Catchment Basins |
- Leak Detection Devices
Catchment Basins
All tanks are equipped with large "buckets" located around the fill pipe that catch any motor fuel that may spill when the delivery hose is uncoupled from the fill pipe.
- Over-fill Protection Devices |
- Cathodic Corrosion Prevention |
- New Tank Materials/Coatings |
- Catchment Basins |
- Leak Detection Devices
Leak Detection Devices
Sensors can detect even small leaks in underground storage tanks and piping. An automatic tank gauging system monitors the volume of product within a storage tank versus the amount of product dispensed to consumers.