Assessment Technologies

There is a gamut of technologies available for assessing the condition of water and wastewater pipes. This section describes the technologies which are already commercialized and substantial data regarding performance and economics are available. The information about these technologies are collected through various sources like research reports, case studies, technology providers and research papers etc. The descriptions below are not a critical review of the technology’s capability, but merely a summary of how the technology works and a brief explanation of science behind them. The description of the condition assessment technologies are in no specific order. The condition assessment technologies can be broadly classified on the basis of type of failures being assessed by the technology. Figure 3 illustrates the classification of the condition assessment technologies

Figure 3: Classification of Condition Assessment Technologies

The classes of condition assessment technology as shown in Figure 3 are defined as follows:

Ultrasonic: These are the technologies which are based on a transducer and receiver mechanism. The transducers produce ultrasonic signals which are then reflected from the deformities or surfaces caused by structural or corrosion failure. The time between sending and receiving the signal is analyzed to understand the thickness of the pipe or other deformities.

Visual: These are the technologies which capture visual images of pipes internally using a camera. These visual images are then analyzed for determining the structural condition of the pipe.

Leak Detection Technologies: These are the technologies which are specifically designed to locate and identify leakages in pipes. The technologies categorized in ...

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...s the mechanism of locating the wire-break event by comparing the arrival times. In case of fiber optic sensors, the origin of the acoustic event is located through the precise identification of the arrival times of these signals at the optical cable. The basic principle of FOS is Optical Time Domain Reflectometry (OTDR). It is defined as the process in which a pulsed pump light that is launched at one end of an optical fiber counter propagates with a probe light launched at the other end. The probe light is amplified by the pump light through the Brillouin Scattering Process and the distributed strain along the optical fiber is obtained from Time Domain Analysis of the probe light. The spatial resolution can be improved by using the correlation between pump and probe lights modulated both in frequency and phase. Figure 8 illustrates the working principle of FOSS.