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Ultralydniveaumåling til skotske vandmonitorer

Ultralydniveau sensor

Ultralydniveau sensor

Scottish Water has praised Halma Water Management’s (HWM’s) SonicSens ultrasonic level sensor, which is being used extensively by the company to monitor flow rates in a wide variety of situations – siphon chambers, Combined Sewer Overflows (CSOs), overflow and storm tanks, weirs, reservoirs and compensation channels. It is a non-contact, highly accurate level sensor and flow meter.

Teknologien bag ultralyds niveau sensorer er baseret på et simpelt princip: En uhørbar højfrekvent lydbølge udledes, rettet mod overfladen, der skal måles. Denne overflade reflekterer bølgen tilbage, og tiden for den reflekterede bølge til at returnere er i direkte forhold til den mellemliggende afstand. Så med en kendt total afstand mellem sensoren og bunden af ​​beholderen eller kanalen findes dybden af ​​vandet ved simpel subtraktion. Strømningshastigheder kan derefter beregnes let, hvis kanalens volumetriske dimensioner er kendt, hurtigere strømning hæver væskeniveauet tilsvarende.

Gerard O’Hara, Project Engineer for Scottish Water, commented on the technology: “The design team here are very happy with the performance of the instruments, and the SonicSens system has been used many times as a part of our award-winning Water Framework Directive contract.” The WFD was introduced in 2000, and made into Scots Law in 2003; its purpose is to maintain, protect and improve the quality and management of all Scotland’s water resources.
En stor fordel ved ultralydsmåling er, at den er uden kontakt, og derfor ikke-kontaminerende og lav vedligeholdelse. SonicSens bygger på dette med en pakke, der indeholder millimeteropløsning, en lang (5-årig) batterilevetid og faciliteten til alsidige fjerntelemetrieremuligheder som GSM, GPRS, radio eller satellitkommunikation. Sensoren selv forbinder til en separat datalogger via et udvalg af standard, ATEX-bedømte, kablede og trådløse kombinationer, med eller uden en Barriere-boks.

These features make the product very well suited to “fit and forget” operations in hard to access locations – once it is installed, it will continue to function as programmed without the need for local maintenance or interaction. Because of this, Scottish Water is using the product for a wide range of applications across its wide area of responsibility, which includes places beyond the reach of telephone lines, cellular reception or even normal access by anything less than a dedicated off-roader.

A recent installation at a compensation weir down in a secluded valley (Image 1) presented potential problems with signal reception. The sensor itself is obviously suspended over the weir – with a known width for flow calculation – and connected to a short-range TRX20 relay unit (IS approved) safely raised above. The datalogger was installed high up on top of the dam (Image 1 inset), where the GSM signal reception is strong enough for the long-range data telemetry.

CSOs are common installation sites for the Scottish Water’s SonicSens systems, as they must be monitored for spill events where heavy rainfall will raise the water level above the storm screen. When this happens, the SonicSens will alert Scottish Water that a storm condition has occurred, and that the screen will need cleaning. Image 2 shows a fairly typical installation, with the sensor looking down at the side of the screen and the logger and barrier box installed in the ‘safe’ area outside the manhole itself (inset).

All ultrasonic level sensors have a ‘blanking’ distance – this is a minimum distance between the sensor unit and the measuring surface. This is required for the device to receive a clean reflected sound wave, one that will be unaffected by the vibrations caused by emitting the sound in the first place. In Image 3, another CSO application, there was not enough room to site the SonicSens in the same chamber as the overflow screen. A new chamber was built over the pipe itself, to measure the water levels from there – but there was still not much space, and the 300mm blanking distance would not be cleared if the water level were raised by a storm condition. In a creative workaround, the sensor unit was installed on its side, along with a reflector plate mounted at a 45 degree angle, situated far enough away to account for the dead-band. Although an uncommon situation, it is a simple and effective solution which further highlights the versatility of such measurement technology.

Nøjagtig niveauføling er vigtig for en lang række forskellige applikationer. Den pålidelighed og fjernkommunikationskapacitet, som SonicSens tilbyder, gør det til et foretrukket valg for mange af disse projekter både i Skotland og i hele verden. Udover selve produktet leverer Halma Water Management viden og ekspertise med sin omfattende trænings- og eftersalgsstøtte, der hjælper med at sikre, at alle behov på fjernniveau er nøjagtige så effektivt som muligt.

For mere information om SonicSens eller anden datalogging, besøg miljømæssig overvågning, flowmåling, vandstyring og lækage-teknologi. www.hwm-water.com or

E-mail: [Email protected] .

Process Industry Informer

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