Why DPLLD for Detecting Line Leaks?

The Veeder-Root Digital Pressurized Line Leak Detection (DPLLD) system is designed to meet your everyday compliance needs in a variety of applications. Our patented technology performs precision line leak testing at full pump pressure for 0.1 Gallons Per Hour (GPH)/0.38 Liters Per Hour (LPH) and 0.2 GPH/0.76 LPH, and a pressure decay test to meet the U.S. Environmental Protection Agency (EPA) EPA 3.0 GPH/11.4 LPH test requirements. DPLLD offers flexible testing and digital reporting options, helping to detect catastrophic leaks. When paired with a TLS-450PLUS Automatic Tank Gauge (ATG), customers can monitor up to 1,178 gallons/4,459 liters of fuel line volume. 

System Features

Equipment Design

  • Pressure sensor is installed easily without breaking piping or adding a new sump  
  • Stainless steel construction meets the challenges of a highly corrosive environment  
  • Test lines at full pressure for quick and accurate results, without restricting fuel flow rate  
  • Not impacted by thermal contraction of fuel in the line due to changes in temperature  

System Functionality

  • Monitors line pressure during dispensing activity to ensure a catastrophic leak is not occurring during a dispense  
    • If a leak is detected at a pre-set pressure threshold, the system will shutoff power to the Submersible Turbine Pump (STP) to minimize environmental damage and help prevent a public safety issue  
  • Conducts test once all dispensing is completed to ensure the integrity of the line  
  • Test can be manually performed to reset alarms  
  • Built-in calibration verification to notify the site operator when the pressure transducer is not operating properly  
  • Auto-Confirm function, when enabled, runs a second line leak test, if an initial test failure occurs, to verify and reduce false alarms due to mechanical issues that may be occurring in other parts of the fueling system  
  • Provides two alarm shutdown options when failure occurs  
    1. Standard Dispenser Shutdown (Alarm and Shutdown)  
    2. Optional No Shutdown (Alarm Only)  


Product Form

TLS-450PLUS Line Leak Digital Transducer Ordering Information

Part Number



DPLLD without SwiftCheck Valve, UL


DPLLD with SwiftCheck Valve, UL


Universal Sensor Module (USM) Interface for Probes, Sensors, and DPLLD


Universal Input/Output Interface Module (UIOM) for Relay Control and Input Signal Monitoring*


Ultimate Testing: Digital Line Leak Detection


Risk Management: Digital Line Leak Detection


Base Compliance: Digital Line Leak Detection

* Required to ensure STP pump control when RJ Diagnostic Alarm is generated or line shutdown to meet regulatory or business needs (Utilizes 5 Inputs and Outputs)


Operating Temperature

-25°F to 130°F (-32°C to 54°C)

Compatible Fuel Types

  • Unleaded Gasoline

  • Leaded Gasoline

  • 5% Methanol

  • Up to 100% Ethanol

  • 15% MTBE

  • Diesel

  • Biodiesel (Up to B100)

  • Kerosene

  • Jet Fuel

  • Aviation Gasoline

  • DEF

Line Flow Rate

120 GPM (473 LPM) Maximum w/ Swift Check Valve

Operating Range

0 – 70 PSI (0 – 4.83 Bar)

Proof Pressure

200 PSI (13.79 Bar)

Maximum Vertical Pipeline Height Above Transducer

11 Feet (3.4 Meters)

Minimum Pump Output Pressure

23 PSI (1.59 Bar)

Maximum Volume of Fuel Monitored

TLS-450PLUS - 1,178 Gallons (4,459 Liters)