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Final Product and Results
This is our final testbed. Inside are PVC pipes on which sensor tests were conducted.
The project consisted of two components: advancing and developing new elements for a sensor based method of leak detection in small irrigation systems, and building a testbed equipped with pipes, valves, and sprinklers.
The functional requirements of the testbed were to have a surface dimension of 1.22 m x 2.44 m (4ft x 8ft) with a height chosen that enables users to manipulate objects inside the testing area. Sponsors desired the testbed to be portable and to have a professional appearance to draw and hold attention of attendees at trade shows or conventions. The testbed must be able to hold 30.48 m (100 ft) of 1.905 cm ( ¾ in) diameter PVC pipe with sprinklers, valves, and solenoid valves to simulate the lengths of realistic piping systems.
It was decided that the testbed would consist of a plywood table with a height of 0.61 m (2 ft) topped with a 1.22 m x 2.44 m x 2.54 cm (4 ft x 8 ft x 1 in) plywood sheet. Lying on top of the plywood base is a rectangular prism container with dimensions 1.22 m x 2.44 m x 0.6096 m (4 ft x 8 ft x 2 ft). The container has an open bottom, with transparent vinyl walls that are 1mm thick (0.04 in), and a polycarbonate (PC) lid that is 0.48 cm thick (3/16 in). The PC and vinyl are attached together by a frame of 0.0254 m x 0.0254 m (1 in x 1 in) aluminum 80/20 bars. The top of the container could slide along the length of the table, and could be taken off for greater table accessibility. The purpose of the closed container is to contain the water spraying from the various sprinklers and simulated leaks. To drain the water in the testbed, drainage holes were drilled at along the edge of one of the 4 ft-long ends of the table.
CAD model of testbed.
Finally, the layout of the piping was designed in such a way that the 30.48 m (100 ft) of pipe was compacted and many types of paths could be created. A drawing of the pipe configuration is shown below. The reason for keeping the piping in the same horizontal plane was to simulate piping in an actual sprinkler system, which typically remains in the same horizontal plane. Because of the 0.61 m (2 ft) height of the vinyl walls, it is possible to create pipe configurations with varying heights nonetheless. A split is introduced midway to simulate the way pipeline splits toward different zones of a lawn, for example. Unions are introduced at 3 points along the setup so that sections of pipe may be interchangeable and thus additional pipe designs may be introduced. The unions also allow for either end of the piping to be connected with a valve and be considered an inlet. Finally, dozens of possible configurations could be created by closing or opening ball valves.
CAD model of piping configuration. Pipe unions allow interchangeability of pipe sections, and several configurations can be created by switching ball valves.
Several conclusions were made from data obtained in all our different trials.
Backyard Trench Results
Leaks detected by using multiple averages to identify changes in acoustic response
The presence or absence of dirt did not influence characteristic changes
Two Acoustic Signatures
Initial Transients: from opening of the valve until the response settles
Steady-State: consistent, stable signature
Testbed Results
Characteristic response for different setups determined by taking multiple runs and averaging the data
Ruptures detected in systems using the full 30 m (100 ft) or more with zones utilizing 8-10 sprinklers
The final design prototype for leak detection was a technique using an acoustic sensor for data collection and a microcontroller for data processing. The basis of the analysis was detection of changes to the physical response of irrigation systems between a normal state and a leaky or broken state. The GenuFlow sensor array had access and control of power to the solenoid valve on the irrigation system and continuously monitored the response of the irrigation system every time it was activated. At the same instant, power is applied to the solenoid and the sensor begins transmitting data to the microcontroller. The sensor data is saved as Trial 1 on the microcontroller’s memory. After 10 seconds the solenoid is turned off and on and the data collection is restarted. The second set of values for another 10 seconds is saved as Trial 2.
The purpose of restarting the system and collecting data is to repeat the transient responses but under different conditions. The pipe system before Trial 1 has been resting, and water has been allowed time to drain, evaporate, or otherwise leave the pipes. The system before Trial 2 is completely full of water because it has not been given any time to clear. If in comparing the response in Trial 1 and 2, the controller finds that the responses are the same, there is indication of a leak or breakage. Experimentation showed that in an unbroken, or normal, system the response for Trial 1 is highly variable compared to Trial 2. Experimentation also showed that the responses of the broken system do not differ significantly from Trial 1 to Trial 2. Therefore, a leak can be detected by comparing Trial 1 and Trial 2 for similarity. The second test consists of a comparison of the data from Trial 2 with a previously saved Trial 2 that is representative of a normal state. If the two responses are different there is indication of a leak or breakage as a cause of the change.
Above is a flow diagram representing the prototype leak detection technique. This method was created based off the patterns we observed in the data.
This data was collected from the backyard sprinkler system, which contained one sprinkler and one rupture.
The characteristic "Normal" data from the Test Bed with a 7 sprinkler configuration.
Rupture simulation data from the Test Bed with a 7 sprinkler system configuration.
This data was collected from the backyard sprinkler system.
This data was collected from the backyard sprinkler system.
This data was collected from the backyard sprinkler system.
This data was collected from the backyard sprinkler system.
Conclusion
As water security becomes a growing concern in times of climate change, it has become more important to manage how efficiently water is used. The startup company GenuFlow strives to invent a non intrusive and inexpensive sensor-based device to detect leaks in small and large scale irrigation systems. They assigned a project that had two components: advancing and developing new elements for a sensor based method of leak detection, and building a testbed for testing and demonstration. An acoustic sensor was used to detect energy of normal and ruptured sprinkler systems in the backyard and front yard of a home, and on the piping of the testbed we created. Different trials were completed by shutting on and off a solenoid valve, and collecting data while the water flows through pipes. Leaks could be detected by comparing trials using statistical methods. The GenuFlow sponsors will refer to the our prototype leak detection method, our data obtained, and the testbed built to further develop their leak detection method and future product.
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