Water Quality Testing Instruments
Water quality testing instruments are used to test water for chemical and biological agents, and to measure variables such as clarity and rate of movement. There are many different types of products. Interface level analyzers are designed to detect the level of an oil and water interface. By contrast, oil in water monitors are designed to measure the amount of oil in water. Potential of hydrogen (pH) instruments measure pH levels. Voltammetry water quality testing instruments vary electric potential while measuring the resultant current, which can be used to determine the chemistry of the conducting medium. Devices use either anodic stripping voltammetry or cathodic stripping voltammetry. Water quality testing instruments that measure conductivity, dissolved solids, suspended solids, turbidity, dissolved oxygen, dissolved carbon dioxide, biological oxygen demand (BOD), chlorophyll, and algal pigments are also available.
Water quality testing instruments differ in terms of form factor or mounting style, user interface, and output options. Some devices are hand held, portable, or modular. Others are designed for laboratory, benchtop, in-situ, or field use. Panel-mounted water quality testing instruments are also commonly available. Like other types of products, they may include an analog meter, digital display, or video display; as well as manual controls, a digital panel, or computer interface. Output options for water quality testing instruments include analog voltages, analog currents, analog frequencies, and switches or alarm relays. An analog current or transmitter is recommended for applications that send signals over long distances. There are two main interface options for water quality testing instruments: serial and parallel. Serial devices use a standard serial communications protocol such as RS232, RS422, RS485 or universal serial bus (USB). Parallel devices use a standard parallel communications protocol such as general-purpose interface bus (GPIB).
Features and functionality are additional considerations when selecting water quality testing instruments. Some devices are temperature-compensated or provided some controller functionality. Others are battery-powered or include self-test features. Event-triggered water quality testing instruments can capture or log data only when a specific event occurs. Water quality testing instruments that are designed for extreme environments can withstand relatively high levels of temperature or humidity, and/or prevent the ingress of dust. Devices with special signal processing or filtering are also available.
