Introduction
Utility locating is a critical process in various industries, including construction, maintenance, and infrastructure development. When it comes to non-conductive pipes, traditional methods of tracing, which rely on the conductivity of the material, are ineffective. This necessitates the use of alternative techniques, such as employing a sonde in conjunction with an electromagnetic (EM) locator. This method allows professionals to accurately trace the path of non-conductive pipes, such as those made of PVC, clay, or plastic.
Equipment Overview
To effectively trace non-conductive pipes, the following equipment is required:
• Sonde (Transmitter): A compact, battery-powered device that emits a signal at a specific frequency. The sonde is inserted into the non-conductive pipe and serves as a traceable signal source.
• Electromagnetic Locator (Receiver): A handheld device designed to detect the signal emitted by the sonde. The locator translates this signal into visual and audio cues, enabling the operator to follow the path of the sonde.
Step-by-Step Process
1. Insertion of the Sonde
The first step involves placing the sonde inside the non-conductive pipe. This can be done through various access points, such as a cleanout, vent, or any other entry that allows for safe insertion of the sonde. Once inserted, the sonde is activated to begin transmitting a signal. The frequency of the signal typically ranges from 512 Hz to 33 kHz, depending on the specific sonde and locator being used.
2. Configuring the Electromagnetic Locator
With the sonde in place, the next step is to configure the electromagnetic locator. The locator should be set to the frequency corresponding to the sonde’s transmission. Many locators have dedicated modes for sonde tracing, which should be enabled to ensure accurate detection. Proper configuration of the locator is essential to ensure it can pick up the signal from the sonde.
3. Locating the Sonde
The operator then uses the locator to detect the signal emitted by the sonde. By moving the locator along the expected path of the pipe, the signal strength will vary, allowing the operator to pinpoint the sonde’s location. As the locator approaches the sonde, the signal will intensify, providing a clear indication of its position beneath the surface.
4. Tracing the Pipe’s Path
Once the sonde has been located, the operator can begin tracing the entire length of the pipe. This involves moving the locator along the pipe’s path, marking the surface at regular intervals to map out the pipe’s route. If the locator is equipped with a depth estimation function, the operator can also determine the depth of the pipe at various points along its path.
5. Verification of the Pipe Route
After tracing the pipe, it is important to review the marked route to ensure it aligns with existing utility plans or expected utility locations. This verification step helps to confirm the accuracy of the tracing and ensures that the non-conductive pipe has been correctly identified and mapped.
Key Considerations
Frequency Selection
The frequency used by the sonde is a critical factor in successful tracing. Lower frequencies, such as 512 Hz, are advantageous for tracing over longer distances and greater depths, while higher frequencies, such as 33 kHz, provide more precise signals in environments with potential interference but have a reduced range.
Signal Interference
It is important to be aware of potential interference from other signals or nearby utilities. Such interference can affect the accuracy of the trace and may require adjustments to the locator’s settings or the use of different frequencies.
Sonde Size and Compatibility
The size of the sonde must be appropriate for the pipe being traced. The sonde should be small enough to navigate bends and obstacles within the pipe while still being large enough to emit a detectable signal.
Conclusion
The use of a sonde and electromagnetic locator provides a reliable method for tracing non-conductive pipes. By following the outlined process and taking into consideration key factors such as frequency selection and potential signal interference, operators can achieve accurate and effective results. This method is invaluable for situations where traditional conductive tracing methods are not applicable, ensuring that non-conductive pipes can be located and mapped with confidence.
