Switches Indicators & Gauges

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.

Analog-to-Digital Converters

Analog-to-digital converters, often abbreviated to ADC, A/D or A to D, are devices which convert continuous signals to discrete digital numbers. Analog signals are variable signals that are continuous in time and amplitude, representing some measurement or physical quantity (e.g. length, width, pressure). By contrast, digital signals are representations of values (e.g. numbers, letters, sounds, pictures) that are discrete (discontinuous).

Usually, an analog-to-digital unit is an electronic device that converts an analog voltage to a digital number proportional to the magnitude of the input voltage. AD converters are used anywhere where an analog system has to be processed, stored or transported in digital form. The resolution of the converter is an indicator of the number of discrete (digital) values it can produce over the range of analog (continuous) values. These are usually stored electronically in binary form, expressed in bits. Consequentially, the level (number of discrete values available) is usually a power of two. Other coding schemes include Gray code or two’s complement binary.

Sidekick Family

Semrad Pty Ltd offers a range of analog to digital converters, counters and relays, compatible with the H-350, H-510, H-500 and other Data Loggers with SDI-12 inputs. The Sidekick Family range can be mixed and matched to fit the application and has low sleep power, typically 100uA or less. They are rugged and weather resistant, with common connectors for quick and easy hookup regardless of the data logger or application.

The Sidekick Family includes:

• the H-411 Quadrature Output – converts a quadrature shaft encoder into a SDI-12 sensor, scaling the encoder position into units of feet, inches, etc.
• H-412 Event Counter- two counter input channels, reports total counts and change. Typically used with tipping bucket rain gauge.
• H-415 Analog to Digital Converter – two 0 to 5VDC input channels. Temperature probles are a typical application it is used with.
• H- 423 SDI-12 to RS-485 Converter- compatible with all SDI-12 loggers and sensors, with enhanced lightening protection.