Underground pipeline detector is one of the necessary instruments for water companies, gas companies, railway communications, industrial and mining, infrastructure units to transform, maintain, and survey underground pipelines. It can quickly and accurately detect underground pipelines without destroying the ground cover. The location, direction and depth of tap water pipes, metal pipes, cables, etc., and the location and size of the damaged point of the steel pipe anticorrosive layer.
The vast majority of underground pipelines are made of metal materials, which can transmit electromagnetic waves inductively. Based on this principle, Wuhan Huatian Electric Power Automation Co., Ltd. has designed and developed an instrument that can intelligently detect the position of the pipeline by detecting the electromagnetic waves emitted on the pipeline— —HTGX-H intelligent pipeline detector. With its superior performance and flexible and convenient detection method, the underground pipeline detector has a large number of users in the fields of electric power, telecommunications, water supply, heating, gas, petroleum, chemical industry, and urban public utilities.
Below we take this HTGX-H intelligent pipeline detector of Huatian Power as an example to introduce the operation method of the underground pipeline detector in detail:
1. Transmitter
There are three ways to connect the transmitter: direct connection, inductive coupling, and induction. We focus on direct links:
direct connection:
(1) Insert the connecting line
Turn off the transmitter and plug the straight wire into the transmitter output socket.
(2) Connect with conductor
Connect the red lead of the connecting wire to the target-non-charged metal part.
(3) Choose the grounding method
Keep the black lead of the connecting wire as far away as possible from the pipeline and at a right angle to the pipeline. Look for metal ready-made grounding points (such as street signs). Be careful not to get close to any nearby underground conductors. If there is no existing grounding point, you can use a grounding solder. Insert the ground drill into the ground as far as possible, and then connect the black lead. To improve electrical conductivity. Can pour water under the board
(4) Select frequency
Audio: Used for good conductors and long-distance positioning.
Intermediate frequency: the intermediate frequency of the audio radio frequency
Radio frequency: general positioning of pipelines with dense pipelines or with non-metallic joints.
(5) Select output power
Choose the high and low gear according to the specific situation.
(6) Check the loop resistance
The transmitter will automatically check the loop resistance and display the measured resistance value on the LCD. The higher the resistance, the weaker the signal of the conductor. Reliable positioning cannot be performed when the resistance value exceeds 30KΩ. You can change the position, it is best to water on the wet ground or on the ground to reduce the ground resistance. If necessary, move multiple times to find the point with the least resistance for measurement. Note: Be sure to turn off the ground before unplugging the ground wire and plug it in. Then turn it on again.
Warning: Never connect directly with live cables. When connecting directly with the cable, make sure that the cable is powered off.
2. Receiver's path tracing
(1) The receiver is turned on.
(2) Check the battery power. When the battery power is low, please replace the battery.
(3) Set the frequency, press the frequency key to set the receiver to the desired frequency. If the active positioning mode is used, the frequency of the receiver should match that of the transmitter. The choice of which frequency depends on the test conditions. Audio and RF have their own strengths. The audio frequency has a large wavelength and a long transmission distance, so the audio frequency is generally used first. If the signal suddenly weakens, disappears, or unexpectedly turns or changes, then radio frequency must be used to verify the result.
Sensitivity setting
The "Gain plus and minus" key is used to increase or decrease the gain, which can increase or decrease the sensitivity. If the digital reading is too low, adjust the "gain plus" key to make the bar graph reading between 40-50 of the entire range. Similarly, if the digital reading is too high, adjust the "gain minus" key to make the bar graph reading between 40-50 of the entire range.
Choose a tracking method
Press the mode key to select the peak or trough tracking method.
Crest pursuit
Keep the receiver of the underground pipeline detector roughly perpendicular to the ground and move the receiver above the pipeline. When the receiver is directly above the pipeline path, the maximum value can be obtained by moving the receiver. See below. When you shake the receiver gradually away from the pipeline path, the bar graph and readings (sound response frequency) will decrease; when you shake the receiver directly above the pipeline path, the segment with the highest intensity value will show the path of the pipeline. It coincides with the plane of the receiver. Then start tracking from the transmitter at a suitable speed, while shaking the receiver left and right. Look at the indicator of the peak reading of the meter.
Trough tracking
When measuring, the plane of the receiver's fuselage must be perpendicular to the direction of the pipeline. On the contrary, when the plane is parallel to the direction of the pipeline, the measured intensity is the smallest. This feature is often used to determine the direction of the pipeline.
By moving the receiver above the pipeline. When the receiver is directly above the pipeline path, the receiver can get the smallest value and the sound response is also very small. When you shake the receiver to deviate from the minimum value, the meter reading will rise to a peak section: and the sound response will be at its highest section. When the receiver shakes along the peak area, the meter reading will begin to decay. Then start tracking from the transmitter at a moderate speed while shaking the receiver from side to side. Watch the signal strength and reading indication.
3. Scanning and searching (sensing search)
Inductive search is the most reliable technique for detecting unknown pipelines. This search method requires a transmitter and receiver and two operators. This search method is called "two-person search". Before starting the search, determine the area to be searched and the possible directions for the pipeline to pass through the area. And set the transmitter to the induction mode. The first person operates the transmitter and the second person operates the receiver. When the transmitter passes through the pipeline, the signal is applied to the pipeline, and then the signal can be detected by a receiver 20 meters upstream or downstream of the transmitter. The direction of the transmitter is consistent with the estimated pipeline direction. The second person carried the receiver at the beginning of the area to be searched, and the direction of the receiver's antenna was kept perpendicular to the direction of possible underground pipelines. Adjust the receiver to the highest sensitivity that will not receive the transmitter signal directly propagating from the air. When the directions of the transmitter and receiver remain correct, the two operators move forward in parallel. The operator carrying the receiver moves the receiver back and forth while walking forward. The transmitter applies the signal to the pipeline directly below, and the receiver detects the signal. Mark the position of the peak detected by the receiver on the ground. Repeat the search in other directions where the pipeline may pass.
4. Induction skills:
Keep the distance between the transmitter and the transmitter. In the induction mode, the transmitter not only transmits signals to the target pipeline, but also transmits signals into the air, which may cause interference to the detection work near the transmitter. To check that the receiver detects the signal from the pipeline instead of the signal directly transmitted from the transmitter, move the transmitter one or two meters. If the pipeline moves along with it, this indicates that the receiver is too close to the transmitter. Another way to check whether the receiver receives the transmitter signal is to point the receiver at the transmitter. If the receiver's response size remains unchanged or increases, it means that the receiver received the transmitter signal directly from the air. In this case, reduce the output power of the transmitter and reduce the sensitivity of the receiver. The receiver may have to be 25 to 30 meters away from the transmitter. Do not place the transmitter on the manhole cover, as this will prevent the signal from reaching the pipeline.