Switches Indicators & Gauges

Sensors and Loggers

Sensors are used to measure quantities and convert it into a signal which can then be recorded by a data logger. The measurements are then interpreted locally or at a remote location, depending on the interface. Sensors are used in many applications, from common everyday objects such as touch-sensitive lamps to fuel gauges, as well as more specialised applications such as water management and meteorological functions.

A sensor’s sensitivity indicates how much the sensor’s output changes when the measured quantity changes, so sensors that measure very small changes have very high sensitivities. These changes can be measured continuously or at certain determined points.

WATERLOG® DH-21 and H-510

The DH-21 consists of a H-310 sensor combined with data logger and software. The sensor is a submersible pressure transducer (device that converts a physical attribute like pressure into a digital signal for the purpose of collecting measurement data). It is designed to let the user monitor ground water, test wells, measure surface water and gauge streams.

The DH-21 features flash memory for data storage, five different logging modes, a ‘point and click’ software interface, capability to store 43, 688 data points (upgradeable to 174, 752), and the choice to display data graphically or in tabular form. It is a rugged device designed to be immune from corrosion, important when leaving it for long periods in remote areas. It takes user changeable long life lithium batteries, with an external 12-volt power option. It has on-site auto-zeroing command and automatic media density correction,  fits 2″ or larder well bores and a field spliceable vented cable.

The H-510 is designed to replace ADRs and other shaft encoder systems, consisting of a self-contained shaft encoder with SDI-12 data logger. It can interface with analog sensors, GOES transmitters, SDI-12 sensors, telemetry systems and modems.

It features a nonvolatile FLASH memory card, auto-offset, built-in keyboard and display, and accepts analog and event inputs using optional ‘Side-Kick’ modules.

Water Management Sensors

Although it seems that water on our planet is abundant, human interference in the water cycle means that water now needs to be managed. While the amount of water on Earth has not changed, the quality of it is changing. By taking part in processes such as agriculture (where runoff polutes rivers and groundwater), fishing (alters marine ecosystems), shipping (released ballast water introduces potentially harmful species to new ecosystems), and industry (carbon dioxide emissions is sequestered by the oceans raising acidity levels), the quality of water is affected.

Even domestic water use has a huge impact, considering the amount of water used just to make ordinary household items, let alone use in showers and pools. For example, it takes 10,855 litres of water to make one pair of jeans, while 15,500 litres of water are used to make just 1 kilo of beef (according to IBM).

As a result water needs to be managed in order to ensure a continuing supply of freshwater. Sensors can be used to record precipitation, monitor groundwater / reservoir / lake levels, monitor saltwater intrusion and salinity. By using these sensors, scientists will be better able to anticipate changes in water availability and demand, define adequate allocations, and inform new infrastructure planning.

Semrad Pty Ltd Sensors

Semrad Pty Ltd offers leading edge technology in a range of water management sensors and precision instruments. These include:

• H-310: submersible pressure transducer for water level monitoring
• DH-21: submersible sensor combined with logger and software
• H-330: Quadrature shaft encoder
• H-510: shaft encoder with SDI-12 data recorder
• H-340: Tipping bucket rain gauge

The WaterLog® Model H-310 is simple to install, use and maintain, and is used to monitor water levels. It is extremely accurate, with linear deviation less than 0.02%, resolution of 1 part in 250,00 and accuracy over temperature range exceeds ± 0.01 feet of water. Corrosion proof, with data transferred digitally and a dry air moisture barrier- all ensure the accuracy of this sensor.

Data Collection Platforms

First of all, what is ‘data’? Data is factual information, whether measurements or statistics used as a basis for reasoning, discussion or calculation, according to the Merriam Webster dictionary. A second definition is ‘information output by a sensing device or organ…that must be processed’, and finally ‘ information in numerical form that can be digitally transmitted or processed’.

A data collection platform is an electronic device that records data from a gauge and at pre-determined times transmits that data through a satellite to a remote computer. It refers specifically to weather devices, whether for complete automatic weather stations or similar hydrological setups. The gauge could be measuring precipitation, such as a rain gauge, or measuring pressure, or groundwater levels. So the gauge is connected to a data collection platform, possibly through an analog-to-digital converter, that then sends the measurements as data to a computer.

Microprocessor Data Loggers

Semrad Pty Ltd offers two microprocessor data loggers: the WaterLOG® Model H-350-XL and the WaterLOG® Model H-500-XL. The first is a controlled pressure sensor/data logger designed for remote operation, and the second is a data logger also for remote operation.

The H-350-XL model can be interfaced with data loggers, chart recorders, remote displays, telemetry systems and GOES recorders. Its key features include: easy to read digital displays that show the stage directly in engineering units, built-in temperature compensation and auto-zero functions, data logging capability using a non-volatile internal storage, four analog inputs, two programmable digital inputs/outputs, operating temperature range of -40° to 60°, a sealed, corrosion-resistant, non-conductive enclosure, and much more.

The H-500-XL model can also be interfaced with a range of data loggers, remote displays, modems, etc, and is ideal for small hydrologic and meteorologic stations. It features a built-in key pad, easy to read display that can be used for complete system configuration or to view measured variables, 2 programmable digital inputs/outputs, data logging capability, quadrature shaft encoder input, and more.