Ways to search for water leaks
The wear limit of networks,The apparent lack of funds in time for the repair and replacement of pipelines , the transfer of heat and water supply networks of departmental enterprises to balance the cities - all exacerbated the problem of on-line diagnostics of pipeline . It can solve diagnostic equipment and special devices .
Currently, there are several methods for finding water leaks from pipes , but do not yet have the sole and effective in all conditions.
The most widely used acoustic method . Devices used for this method, the work may be divided into three groups. The first is the control with the use of the non- filtered ( such as ” Alternative- 07″ ) . The spectrum of the acoustic signal flowing water at different pressures and dimensions of the defects is in the range 100 - 3000 Hz. By working with these devices , the operator uses to analyze and separate the useful signal from the noise only your brain and intuition. This device works well in a rural area away from roads . The work of this class of devices is determined only by the sensor sensitivity , which can vary from 80 mV / g ( Leak “Search” ) to 500 mV / g ( Leak “Alternative- 07” ).
The second group of devices most mass . This is the electronic devices (digital or analog ) filtering the input signal. The main purpose of the filters - the selection of the desired signal at its very noisy in urban environments. The higher the order of the filter , the more quality is noise reduction. Main technical characteristics of these devices - the level of filtering that varies within a second ( “Search” ) to the eighth order ( “The success of ATG- 5”) , as well as the number of filter bands and the presence of sensors for a variety of soils - asphalt , grass, clean earth , snow .
The third group includes leak detectors to function pseudo . This is a tool for determining the distance to the leak from the difference between the noise intensity at different distances from the leak. Most work for the third method is used to display noise and a special type of sensor ( success AT -1).
One well known way to detect leakage from a pipeline correlation method . Correlation leak detector - it’s quite expensive devices to work with them to create a specially trained group. This method is used in complex noisy areas. The main advantage over acoustic devices - sensors are connected to the pipeline at only two points . As a result of signal processing is determined by the distance to the leak from one of the sensors. This method is more efficient in finding leaks in duct laying the pipeline . The probability of detecting leaks from 50 % to 90 %. The main problem of the correlation method is that it is more than an acoustic sensitive to irregularities in the inner tubes - foreign objects , bends , bends , deformation, change in diameter .
When using both acoustic and correlation method leak must know the plan of the route and location of supports , bends , pipe bends , tapered sections , valves.
Another way is to control the leak of the temperature distribution on the surface. Used to control the type of contact thermometers Degree , TC -3 , TC -5 with immersion probe pyrometers C- 110 ( Torch ) and thermal imaging of various modifications. The main characteristic of leakage under the control of this method is the change in temperature on the surface of the heating mains. Changes in temperature range from fractions of a degree to a few tens of degrees .
When working with contact thermometers need to focus not on the measurement accuracy , and sensitivity. Since the thermometer has a sensitivity of 1 Degree Co, and TC -5 - 0,1 oC. One of the most important characteristics of the thermometer with immersion probe is the speed of the probe. Most of the current probe of domestic and imported using resistive sensors are speed of 20-50 seconds.
With a large number of measurements , and the need to go through the whole track, it complicates the use rabotu.Zhelatelno quick immersion probes ( TK- 3 . , TC -5 , TC -7) with a speed of 7.3 seconds.
For speed and convenience of contact less temperature control devices - pyrometers differ significantly for the better. Thus , the speed pyrometers C- 110 ” Torch” , C- 210 “Salute ” C- 300 ” Favorite” is from a fraction of a second to 2.1 seconds. Pyrometer allows almost continuously measure temperature, which increases the efficiency and reliability of the control . This can be obtained quickly as longitudinal temperature distribution and transverse to define the boundaries of thermal fields . Due to its low cost , simplicity and high reliability of this method is the preferred method of thermal control.
Thermal imaging method , due to the high cost of equipment and the need for special training , is mainly used for periodic monitoring of heating during prophylactic examination.
For less common control methods include gas analysis . Empty pipe filled with a special gas. The leak is determined by the output of gas analyzers to the surface.
Pressure method is used to control the tightness of pipes and valves . In the pipeline is pressurized water or gas and to reduce the pressure of judging the health of valves or the leak.
search for water leaks.
There are methods of controlling the electromagnetic field on the surface of the pipe . These methods can detect over-wetting the soil under the ground, but they are quite expensive and are often poorly worked out.
Each method is effective in some conditions and less effective in another. Thus, when trench less laying of pipelines, the most effective use of acoustic monitoring method . Works fine correlation and thermal methods . The latter can only be used when the hot coolant leakage , i.e. under the control of heating systems and hot water supply pipelines .
It is much more difficult to control the leak with duct piping . In this case, the efficiency of acoustic and correlation techniques preserved and heat method is less acceptable, since spreading of the hot water in the channel , ” blurs ” thermal image on the surface. To detect leaks have to analyze the entire site . Corrections shall be made on the slopes , possible filling with hot water cavities in the ground , to take into account the difference of thermal conductivity of materials and the quality of insulation.
The most effective use of combined methods of control. This greatly increases the accuracy of detecting leakage. Most often share the acoustic and thermal control methods . For example, a set of master - Heat Engineering ” Cardinal” Company ” TECHNO -AC ” includes acoustic Reagents ” Success- ATG- 5 ” , the infrared pyrometer C- 110 ” Torch” and the thermometer TC -5.
When working with a set , first measured the thermal fields pyrometer as the most rapid and simple instrument. In case of apparent anomalies , control of these areas is made using a leak detector . This method is now widely used by businesses of St. Petersburg and the Leningrad region.
The complex of the leak detection begins with the receipt of the plan showing the pipeline bends, constrictions , valves, bearings , turns, bends.
You must first determine the location of the wells. In some cases it may be difficult to do so. For example, when you close the hatch wells asphalt , soil or leaves. In winter, the hatches are often covered with snow and ice. In this case, you can either use a pyrometer , if the heating main , or a metal detector , for example, mark ” Luke ” , which allows to detect metal hatch in the soil to a depth of 100 cm
After this, pipeline , as sometimes flow diagram does not correspond to the actual laying of pipelines. The heating is most often seen with the naked eye on the green grass or the snow melted , but pipelines under roads , asphalt, concrete, hard to detect accurately .
For these purposes are often used locators electromagnetic and optical pyrometers.
The basic principle of the search line is to build the electromagnetic field around the line by transmitting an electrical signal from the generator to the pipe or contact induction method . In the case of the induction process plummets energy emitted by the pipe signal , which significantly reduces the length of the trace. Modern generators are used primarily at frequencies near 1 kHz 9 kHz and 10 kHz. Frequencies import generators lie near 1 kHz and in the range of from 9 to 10 kHz. In Russia the use of generators above 9 kHz require a special permit . Apart from the magnitude of frequency generator , its stability is important , because narrow band radiation allows narrow band receivers that at the same output power of the generator , sometimes several times the length of the trace section .
Receivers These receivers sets may differ significantly in their characteristics.
The simplest type of broadband ” Ghost ” no filtering. Little protection from interference. These receivers are designed primarily for work in rural areas. More sophisticated receivers ( Success- K- 5, K- 7) have a narrow band reception ( 10:20 + Hz), additional filtering (usually 4 or 8 orders of magnitude) . They can operate in a passive mode to the search cable under tension.
To contact connecting the generator to the pipeline , it is necessary to fix one of the contacts on the tube , and this requires to go down into the well. For safety before descending sure to check for the presence of methane in the well . For this purpose designed methane detector ” Methane -9M .”
To evaluate the corrosion of the pipe wall thickness gauge should be used , such as brand , ” UT- 80 .”
The most costly mistake at the opening of the soil after the leak detection , power cable is broken . In order to avoid this problem is to make a preliminary survey of the suspected leak . The survey was conducted specifically Cable locator or locator with enhanced features. These provisions have the equipment : leak detector with passive search function cable Success- ATP- 4 , locator Success K- 5, success of ATG- 5.
The most convenient and cheapest solution is necessary to recognize the creation of complex -type instrument success of ATG- 5, ATG- 7. The unified electronic control unit and a set of dedicated sensors allows to use the same device for water leak detection , and for routing cables and piping . The cost of the device is several times less than the price of a set of devices. This integrated device must be supplemented by a thermometer TK- 5, C- 110 pyrometer “Torch ” metal detector ” LUC ” feeler gauge - UT -80 methane detector ” Methane -9M .” All devices are available and most are made by ” TECHNO -AC ” Kolomna . The entire set can be accommodated in the back seat of the car type 21099 or trunk. If the leak detector kit complete correlation ATC -5 , the specialist can take almost any task to find the leak .
CONCLUSIONS :.
Leak detection of pipelines is a complex technical task, which requires special equipment.
The main methods of control are - acoustic , correlation , heat .
The most effective method is using acoustic type of success ATG- 5 in combination with a thermal control pyrometers C- 110 ” Torch” .
Solution of the leak detector requires the additional use of complex instruments : like ” Luke ” , pressure gauges, thickness gauges , thermometers , flow meters.
An integrated approach to the task of identifying water leaks from the pipeline using devices developed and supplied by the Company ” TECHNO -AC ” can significantly improve the accuracy of detection of an emergency site.
