Advantages and disadvantages of gas detector line system and bus system
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The bus system is also called RS485, and the split line system is also called 4-20mA model. At present, the gas detector mainly adopts these two wiring methods, and each has its corresponding alarm host.
Generally speaking, the vast majority of bus system gas detectors use 4-core shielded wires, 2 power lines, and 2 signal lines, and the transmission distance is relatively long, about 1-2Km; Core wire, 2 power lines, 1 signal line, the negative pole of the power supply and the signal line are common, and the transmission distance is relatively short, within 1Km.
Choose the bus system or the split line system, and the details should be confirmed according to the actual working conditions. 1. The number of gas detectors to be connected. If the number of probes is more than 8, it is recommended to choose the bus system. This can reduce wiring difficulty and wiring cost. All probes are connected to the host through one cable, and a maximum of 256 gas detectors can be connected in theory; if the number of gas detectors is less than 8, the split-line system can be selected, and each probe can be connected through a separate The cable is connected to the host. 2. Distance. In actual working conditions, since the installation position of each probe and the distance between the probes vary from far to near, when the distance is relatively long, it is recommended to use the bus system. The general transmission distance of the bus system is 1-2Km, and only one main line is needed Cables are enough, and all probes can be connected to the main line; in addition, the transmission distance of RS485 can be increased by adding repeaters, and the distance is theoretically unlimited. Use split lines for short distances. 3. Signal processing needs. In many cases, the detection data of the gas detector needs to be processed multiple times. 4-20mA is a standard industrial signal, which can be connected to various PLC and DCS systems, but when it is necessary to save data and display data twice, it needs to use RS485 signal.
Here is a summary of the advantages and disadvantages of the bus system and the split line system:
Advantages of bus system
The signal is uniform and the probability of failure is low. The bus control system does not have such inconvenient factors at all, and the data is transmitted in the same form on the data line, which enhances the reliability of the data.
The wiring is simple and the workload is small. The obvious advantage of the bus system is that the amount of wiring is small, the wiring is simple, and the cost is low. Four-bus system, two signal lines, two power lines, simple and convenient wiring.
Disadvantages of bus system
Signal delay. The data is flashed out one by one, especially when there are a lot of probes.
Power problem. All probes are powered centrally by the host. When the number of probes is large, the power supply capacity of the host is insufficient, so local power supply is required.
Advantages of split line
Data synchronization is good. Compared with the bus system, each gas detector in the split-line system communicates with the controller independently, which can transmit the on-site conditions to the control part in a timely manner, so that the monitoring personnel can make timely and effective judgments, and the corresponding peripheral control equipment can be timely Effectively make corresponding control actions to avoid dangerous accidents.
Power without limitation
Disadvantages of split line
Wiring is complicated. The amount of wiring is large, the workload is heavy, the wiring is complicated, the installation and construction are complicated, and the installation and material costs are high.
There is a lot of signal interference.
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The water leak detection methods that utilities deploy to detect underground system leaks can generally be divided into two main categories: proactive leak detection and reactive leak detection. Historically, both categories have relied on methods with severe limitations.
Reactive leak detection generally requires waiting for a leak to &#;surface,&#; to present evidence of itself, and then everyone reacts. Evidence can include anything from deformations in the ground to low water pressure, to a burst water main that&#;s suddenly flooding a neighborhood, by which point you&#;re reacting to an emergency instead of a problem.
The shortcomings of reactive water leak detection methods are apparent. For example, a leak that finally presents as a burst water main can do considerable damage that may cost as much to repair as the leak itself. Or it may just leak huge amounts of water for years but never be detected. In fact, some leaks may never surface, and they can lose water and money for a decade or more before they&#;re found and repaired if they ever are.
In fact, surfacing leaks account for only about 20% of water loss for the typical distribution system. Most real water loss and non-revenue water costs are due to non-surfacing leaks and so require a more proactive approach to leak detection.
Non-surfacing leaks account for approximately 80% of NRW in a typical situation. Proactive water leak detection is essential if one is to make serious headway in loss reduction. But traditional proactive water leak detection methods have their shortcomings as well.
Most proactive water leak methods deployed by utilities use some form of sound or radar detection. Acoustic leak detection uses extremely sensitive audio equipment to &#;listen for leaks&#; in underground systems from above the surface. Leak noise correlation also uses sound by placing sensors in contact with locations on a pipe with a suspected leak and recording the signals for analysis. Ground penetrating radar uses electromagnetic waves instead of sound.
All three are proactive methods and can be fairly effective at pinpointing leak locations &#; provided you know where to generally look. But they are impractical for proactive system-wide leak detection in large and even most small systems.
Leak noise correlation is a fairly complicated procedure that requires significant capital equipment investment and access to several locations along the pipe, which can mean digging for pipe access. It also requires knowing approximately where to look &#; even though the prevailing fact of non-surfacing leaks is that you don&#;t know where to look. Thus, leak noise correlation is not frequently used for proactive, system-wide leak detection.
Ground penetrating radar also requires capital investments and trained technicians to operate and interpret. Soil conditions, including a high saline content, can limit their performance.
Acoustic water leak detection equipment is much more widely used for system-wide proactive assessment. Even so, it&#;s still a notably expensive and limited approach.
First, it&#;s extremely resource-intensive, thus beyond the reach of many water system operators. Deploying acoustic leak detection equipment system-wide is done by sending teams of technicians into the field with headsets and listening devices, with which they literally walk the entire system &#;listening for leaks&#;.
Even in the most advantageous situations of geographic size and actual pipe system length, it can take years to assess an entire system. Even a midsized system can take half a decade, and by the time its full length is finally surveyed, the results can already be out of date.
Pipe material can also limit the effectiveness of acoustic methods, particularly with PVC pipe, a mainstay of certain systems. PVC does not transmit sound sufficiently for acoustic leak detection equipment to function optimally.
Satellite-based leak detection is a groundbreaking advance in leak detection technology that overcomes many limitations of traditional methods. Satellite-based leak detection gives system operators the ability to proactively detect leaks quickly and efficiently across an entire system for the very first time!
ASTERRA Recover, which was first used commercially in , is currently the only leak detection system in this category, and it works very differently than the traditional leak detection methods we&#;ve mentioned.
Satellite-based leak detection deploys synthetic aperture radar (SAR) to detect soil moisture over vast areas, up to 1,400 sq miles at a glance. The signal uses a wavelength on the electromagnetic spectrum (the &#;L-band&#;) that can penetrate earth, sand, asphalt, forests, or clouds, and is able to reach a depth of approximately three meters below the surface.
Working in any weather or light conditions, Recover detects the presence of processed drinking within the soil surrounding pipe systems. Soil moisture is correlated to the pipe system, creating a system-wide map of leak locations to verify and repair.
A map of leaks throughout the entire system can be produced literally within days, instead of the years walking the system with acoustic equipment would require. And a system can be reassessed as often as its operator deems necessary.
There are no capital investments for equipment with Recover satellite-based leak detection. Data from the satellite images are viewed through the EO Discover platform, which also provides data and insights on water and money saved, reductions in energy use and carbon emissions, and other key benchmarks. It also gives users the ability to track the progress of leak remediation projects.
ASTERRA Recover and satellite-based leak detection represent the first meaningful breakthrough in leak detection in over 80 years. We encourage you to learn more about its success in reducing real water loss.
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