UST Programs - LG 113

Issue Date: May 27, 2004
Revision Date: June 10, 2004

SGB (Sicherungsgeratebau GmbH)

Overpressure Leak Detection System Model DLR-G

CONTINUOUS INTERSTITIAL LINE MONITORING METHOD (PRESSURE/VACUUM)

Certification:
Certified per European leak detection standard EN 13160-2, Part 2, as a Class I leak detection system.

Operating Principle:
System uses pressurized nitrogen gas to continuously maintain an overpressure within the interstitial space of double-walled piping. System is designed to activate a visual and acoustic alarm before stored product can escape to the environment. System is capable of detecting breaches in both the inner and outer walls of double-walled piping.

Alarm Condition:
System alarms when a leak occurs which causes the pressure within the interstitial space to decrease to the “Minimum Interstitial Space Alarm Pressure” (see table below).

Applicability:
Double-walled piping, underground or aboveground, having a design strength capable of safely sustaining the required operating pressure in the interstitial space. Piping may convey flammable, combustible, or non-combustible liquids including gasoline, gasohol, diesel, heating oil #2, kerosene, aviation fuel, motor oil, and acidic or caustic solutions. Note: Conveyed product must not react with pressurized nitrogen. Interstitial space to be monitored must not exceed 150 ft3.

Manufacturer's Specifications:
The leak detector can be configured to monitor primary lines with operating pressures up to 120 psi, as indicated in the following table. The interstitial space shall be rated for the operating pressure (interstitial space refilling “off” pressure) of the leak detector, as indicated in the following table. Pressures shall be set as follows:

The DLR-G leak detector is not explosion protected. Do not install in a volatile, combustible or explosive atmosphere. Install the detector inside the building in a dry, frost-proof area. When using nitrogen gas, ensure that the room is ventilated according to applicable codes due to asphyxiation hazard. If installed outside in a protected area, place in a weatherproof protection box with a transparent lid.

Calibration:
Functional and operational safety tests must be performed annually in accordance with manufacturer's instructions.

Comments:
Interstitial space is tested continuously.
System can operate in two modes: with or without a nitrogen bottle continuously connected. Nitrogen bottle must be connected unless the piping is “impermeable” (e.g., double-walled steel).
Pressure is generated by inert gas bottle (nitrogen) and is measured and controlled by a pressure switch.
This system may not be compatible with all secondarily contained tanks and/or piping. Always consult with the tank and/or piping manufacturer and the manufacturer's applicable recommended installation practices before installing this system, or damage may be caused to the tank or piping by its use.