Exceptional Precision for Water Quality: The Hanna Instruments HI98713 Precision ISO Turbidity Portable Meter is expertly engineered for high-accuracy water quality measurements, delivering consistently reliable readings, particularly across challenging low turbidity ranges. This advanced instrument boasts a cutting-edge optical system that not only ensures precise results but also guarantees long-term operational stability by actively minimizing interference from stray light and potential color variations within the sample. To maintain optimal performance, periodic calibration with the supplied standards effectively compensates for any slight fluctuations in the intensity of its infrared LED light source. Furthermore, the use of specialized optical glass for its 25 mm round cuvettes is critical, meticulously designed to ensure the utmost repeatability of every turbidity measurement.

Features at a Glance:

• Ratio Measurement Mode: The HI98713 meticulously measures turbidity using an advanced ratio method, incorporating both 90° and 180° light detectors to achieve exceptional accuracy across the full 0.00 to 1000 FNU (Formazin Nephelometric Unit) measurement range.
• Multiple Reading Modes: Adaptable to various needs, the meter offers several reading modes: Normal measurement for standard readings, Continuous measurement for ongoing monitoring, and Signal Averaging measurement for enhanced stability and precision in challenging conditions.
• ISO Compliant: Fully compliant with and exceeding the stringent requirements of ISO 7027 for turbidity measurements, the HI98713 utilizes a high-performance infrared LED light source, making it ideal for applications requiring ISO methodology.
• Comprehensive Calibration: The HI98713 features a robust calibration function that precisely compensates for any variations in light intensity. Users can perform a highly accurate two, three, or four-point turbidity calibration using the included high-quality standards (<0.1, 15, 100, and 750 FNU). Calibration points are also fully customizable if user-prepared standards are preferred.
• AMCO AEPA-1 Primary Turbidity Standard: The AMCO AEPA-1 standards supplied with the HI98713 are globally recognized as primary standards by the USEPA. These non-toxic standards are meticulously crafted from styrene divinylbenzene polymer spheres, ensuring uniformity in both size and density, which translates to exceptional stability, reusability, and a long shelf life.
• Fast Tracker™ - Tag Identification System (T.I.S.): For advanced field applications, the HI98713 integrates Fast Tracker™, an innovative Tag Identification System designed to significantly simplify data collection and management. This feature enables users to effortlessly record the exact time and location of specific measurements or series of measurements by utilizing iButton® tags placed near sampling points, streamlining fieldwork. Each iButton® tag contains a unique computer chip encased in durable stainless steel.
• GLP Data Functionality: The HI98713 incorporates comprehensive Good Laboratory Practice (GLP) functions, ensuring full traceability of your calibration conditions. This invaluable feature automatically records crucial data such as calibration points, date, and time, promoting data integrity and accountability for regulatory compliance.
• Extensive Data Logging: The instrument's substantial internal memory can store up to 200 measurements, providing ample capacity for comprehensive data collection. These logged readings can be easily recalled at any time directly from the instrument for review.
• Effortless Data Transfer: For further data storage, in-depth analysis, or detailed record-keeping, all logged data can be seamlessly downloaded to a Windows® compatible PC. This transfer is facilitated via either the convenient USB or RS232 port, utilizing the dedicated HI92000 software.
• Backlit Graphic LCD Display: The HI98713 features a clear, intuitive backlit graphic LCD display. This user-friendly interface presents all messages in plain text, making them exceptionally easy to read and guiding the user step-by-step through routine operational procedures and calibration processes, even in low-light conditions.

Significance of Use

Turbidity's Role in Water Quality: Turbidity remains one of the most critical parameters for assessing the quality of both drinking water and natural water bodies. While historically considered an aesthetic characteristic, robust evidence now demonstrates that effective turbidity control acts as a vital safeguard against waterborne pathogens. In natural environments, turbidity measurements are commonly performed to gauge overall water quality and its suitability for supporting aquatic organisms. Historically, wastewater monitoring and treatment were primarily driven by turbidity control, and even today, measuring turbidity at the end of the wastewater treatment process is essential for verifying compliance with stringent regulatory standards.

The Nature of Turbidity: Turbidity in water is fundamentally an optical property that causes light to be scattered and absorbed rather than transmitted directly through the liquid. The scattering of light is predominantly caused by the presence of suspended solids. Consequently, higher turbidity levels correlate directly with a greater amount of scattered light. It is important to note that even highly purified liquids will exhibit some degree of light scattering, as a true "zero turbidity" solution is practically unattainable.

ISO Method for Turbidity Measurement: The ISO standard for turbidity measurement, as employed by the HI98713, utilizes an infrared wavelength of light (860 nm) that falls outside the visible spectrum. The primary advantage of this ISO method over the EPA method (which uses a tungsten lamp producing visible light) is its significant reduction of color interference. Since the ISO method operates outside the visible wavelength range, the color inherent in a sample does not absorb light and thus does not interfere with the turbidity measurement, ensuring more accurate results for colored samples. (Note: The USEPA typically prefers tungsten lamps for drinking water as it is expected to be clear and they offer better accuracy at very low ranges).

ISO 7027 Requirements: The requirements for an optical turbidity meter measuring diffuse radiation in low-range applications (e.g., drinking water), expressed in Formazin Nephelometric Units (FNU) according to ISO 7027, are highly specific:

• The wavelength of the incident radiation must be 860 nm.
• The spectral bandwidth of the incident radiation must be less than or equal to 60 nm.
• There must be no divergence from parallelism of the incident radiation, and any convergence should not exceed 1.5°.
• The measuring angle, theta, between the optical axis of the incident radiation and that of the diffused radiation, must be 90° ±2.5°.
• The aperture angle should be between 20° and 30° within the water sample.

Compliance: The HI98713 is designed to meet and exceed all meter criteria specified by ISO 7027, ensuring reliable and compliant performance for your turbidity analysis needs.