Pergam Italia
Via della Volta 183
25124 Brescia
Tel: +39 030 3531423
Fax: +39 030 3469939

Pergam SELMA Roof G4
Pergam Suisse

Pergam SELMA Roof G4

Street gas leak inspection system. Vehicle based gas leak detection.

SELMA – Street Evaluating Laser Methane Assessment

SELMA (Street Evaluating Laser Methane Assessment) is one of the most modern gas leak detector device. The main application is the Leak detection in gas pipelines, compressor stations and other potential sources of methane emissions. The principle of SELMA is a pulsating infrared laser, which is directed to the location to be examined. The data from GPS receiver allow binding of measured gas concentration to real geographical coordinates. The primary goal of the SELMA System is to locate and identify potential threats and vulnerabilities of the naturalgas distribution system. These vulnerabilities are identifi ed using the SELMA system.

Methane Detection Distance

The infrared laser beam can directed on each item / location in a distance to 1000 meters. If a methane cloud is crossing the laser beam at any point between the system and the reflection object the discharged amount is recognized and will be measured. The SELMA system is provided with the Pergam-GLD-Online-Software. This software provides a real-time monitoring, data collection including analysis. The intergrated GPS gives you the precise location of the detecting leaks. Detection distance — up to 1000 m.

Combined methane leak detection solution: managed laser scanner plus precision gas detector. SELMA (Street Evaluating Laser Methane Assessment) is designed to search for gas leaks in urban environments. It is able to detect even a weak gas concentration moving at a speed of 37 mph (60 km/h). Useful for: City Inspection; Country Inspection; Underground Gas Storage; Transportation Gas Pipeline.

SELMA is designed for high-accuracy inspection (leak detection from 0.1 ppm) of a wide range of gas facilities: from gas fi elds and gas transport system to gas consumers. The system can be installed on any vehicle — a passenger car, a lorry, an off-road or a segway. The high economy of the laboratory is due to the optimal speed of inspection — up to 50 km/h. The device can be operated in a completely unmanned mode. Measurement readings with GLONASS/GPS position are stored in the device.

The Mobile Laboratory with Gas Leak Detector can be used in activities related to transportation of natural gas, and in other branches of the industry for detection of natural gas leakages from high and low pressure gas pipelines and other methane sources. Remote gas detection can be made at distances up to 50 m from the Mobile Laboratory, by measuring absorption of the laser radiation by gas. Detector is intended for measurement of gas concentrations, mainly methane, in ambient air.

SELMA Gas Leak Detector

360° leak detection

SELMA Roof remote detector

SELMA Roof is a remote laser detector on a rotary platform. It is mounted on the vehicle top to monitor gas leaks within a radius of 492 feet (150 meters). The working principle of this methane gas leak detectors is based on a pulsed beam from a diode laser.

SELMA Roof features

  • Effective both during parking and while driving;
  • Scanning modes: directional (manual), circular;
  • Methane detection through window glass;
  • Laser radiation is safe for humans;
  • No special person required; a driver/operator is enough;
  • Built-in GPS receiver for accurate leak location;

Principle of Remote Gas Detection

SELMA G4 is based on the utilization of laser absorption spectrophoto-meter of methane gas for gas mesurement. The system detects natural gas leaks by emitting a laser at a particular wavelength and analyzing the light reflection from an object to determine how much was absorbed by the methane in the natural gas.

The measured gas volume is expressed by methane column density (ppm × m): methane density (ppm) multiplied by thickness (m). The Optical Unit (OU) of the SELMA G4 detector installed on the Pan&Tilt system with panoramic scanning capability and equipped with joystick to manage laser on the pipeline.

Principle of Remote Gas Detection

Pergam SELMA Roof technical characteristics



SELMA Roof mini

Maximum detection distance up to 492 feet (150 m) up to 262 feet (80 m)
Vehicle speed 31 mph (50 km/h) 31 mph (50 km/h)
Detector sensitivity    
at a distance of 98 feet (30 m) 5 ppm×m 5 ppm×m
at a distance of 164 feet (50 m) 8 ppm×m 10 ppm×m
at a distance of 262 feet (80 m) 13 ppm×m 20 ppm×m
at a distance of 328 feet (100 m) 25 ppm×m
at a distance of 492 feet (150 m) 60 ppm×m
Scan angles    
azimuth ± 360° ± 360°
elevation 45...135° 45...135°
Laser type diode, class I diode, class I
Laser power 15 mW 15 mW
Laser wavelength 0.065 mil (1.65 μm) (safe for humans) 0.065 mil (1.65 μm) (safe for humans)
Power supply 12 V 12 V
Operating temperature 14...122 °F (-10 ... +50 °C) 14...104 °F (-10 ... +40 °C)
External unit dimensions 9.25 x 7.87 x 12.79 inches (235 × 200 × 325 mm) 7.76 (D) × 12.4 (H) inches
External unit weight 33.07 lb (15 kg) 15.43 lb (7 kg)


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Pergam Italia

Via della Volta 183
25124 Brescia

Tel: +39 030 3531423
Fax: +39 030 3469939

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