Liquid Sensor Placement

Written by: Brian Pottebaum, Director of Training Services

All new tank and piping installations or piping replacement of 50% or more require secondary containment systems, which include double walled tanks and piping, as well as contained sumps. Additionally, piping replacements within 10 feet of the dispenser require under-dispenser containment.

These containment systems are designed to capture any spilled or leaked product from the piping system. If working properly, leaks from the primary layer of product pipe will be contained within the secondary layer and collect in a contained sump that is monitored visually once a month or continuously with a liquid sensor.

Liquid sensors must be properly placed to get accurate reads and function as designed. The sensor should be installed in every sump and located at the lowest point or within the bottom two inches. In addition, the sensor should also be anchored securely and placed in the area closest to the piping or wherever product is most likely to collect within the sump.

When programmed into the tank monitor, the sensors can completely turn off the fueling system if it goes into alarm. This is known as a positive shutdown. Sensors can also be programmed to trigger an alarm only, but someone must be available to respond immediately.

Sites with liquid sensors are required to document every month that they are monitoring and maintaining the secondary containment systems properly. Operators should have twelve months’ worth of records available for review. Sensor status reports or manual logs are acceptable forms of record keeping.