Product

PROWLER Theory of Operation

The PROWLER system is a unique patented system for detecting leaks of hydrocarbons and other hazardous materials from pipelines, underground storage tanks, fuel hydrant systems, and other applicable applications. The PROWLER system operates by the detection of vapors that migrate through the soil or other media from the leak source to the tubing, which captures a sample of the vapors. Essentially, the gas vapors diffuse into the tube to achieve a balanced vapor concentration (equilibrium) between the outside and the inside of the tube.

Since these vapors can emanate from either liquids or gasses, the system can monitor for either substance. The contents of the tube are periodically pumped and analyzed for changes from the ambient hydrocarbon backgrounds levels. Among the PROWLER system's unique features are its capability to operate in the presence of water (e.g. areas where the water table is high), its ability to detect very small leaks, the ability to analyze the background environment, and its ability to quickly and accurately locate the source of the leak.

Applications to date include gas and chemical pipelines, fuel hydrant systems, and underground storage tanks. Substances that have been monitored include benzene, pentane, ethylene, ethylene oxide, fuel oil, jet fuel (JP-4 and JP-8), sour gas (i.e., containing hydrogen sulfide), diesel fuel and gasoline.

Leak Determination

The Pump/Detection unit (PDU) does not make an exact determination, depending on the sensor, if the bump or peak is actually a leak from the pipeline. It only alarms when the newest recording varies from the Master recording. Because of the high sensitivity of the system, natural occurring sources of vapor may cause results similar to a leak signature. If it is determined to be a natural source, a new Master recording should be made to accommodate the changes.

The illustration shown below presents a preview of the software utilized in determining any anomaly that would lead to an investigation of what type of gas is being picked up by the system and if it is actually pipeline product. If further investigation is necessary, it is simply a matter of capturing the exhaust air output of the PDU during the period that the peak appears.

To do this, a two position valve is attached to the gas output connector on the PDU. The other side of the valve directs the output of the PROWLER to a standard gas sampling bag. As the PROWLER operates in the sampling step, the operator watches the output of the system until the point when the peak begins to appear. Immediately change the valve to direct the output air to the gas sampling bag. When the peak stops, return the valve to the original position. Now a captured sample of the vapor causing the peak is in the sampling bag. It may then be taken to a lab to determine the contents of the sample. Once identified, it is determined whether the source of the peak is a natural one or from the pipeline. If the gas is confirmed to be monitored product, the leak location would be investigated.

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