Exceptional Precision for Water Quality: The Hanna Instruments HI98703 Precision Turbidity Portable Meter is engineered for unparalleled accuracy in water quality measurements, particularly excelling in the critical low turbidity range. This advanced instrument is built upon a state-of-the-art optical system that not only ensures consistently precise results but also guarantees long-term stability by effectively minimizing interference from stray light and color within the sample. For maintained accuracy, periodic calibration with the included standards is crucial and compensates for any minor variations in the intensity of the meter's tungsten lamp. Furthermore, the use of specialized optical glass for its 25 mm round cuvettes is paramount, designed to maximize the repeatability of every turbidity measurement.
Features at a Glance:
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Multiple Reading Modes: The HI98703 offers versatile measurement options, including Normal measurement, Continuous measurement for ongoing monitoring, and Signal Averaging measurement for enhanced stability and precision.
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EPA Compliant Measurement: Designed to meet and exceed the stringent requirements of EPA Method 180.1 and Standard Methods for turbidity measurements. When operating in EPA mode, all turbidity readings are automatically rounded as needed to ensure compliance with reporting regulations.
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Comprehensive Calibration: Achieve superior accuracy with a robust two, three, or four-point turbidity calibration. This process utilizes the supplied high-quality standards (<0.10, 15.0, 100, and 750 NTU). Additionally, calibration points can be customized if you choose to use user-prepared standards.
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AMCO AEPA-1 Primary Turbidity Standard: The AMCO AEPA-1 standards provided with the HI98703 are officially recognized as primary standards by the USEPA. These non-toxic standards consist of styrene divinylbenzene polymer spheres, uniform in both size and density, offering exceptional reusability and a long, stable shelf life.
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Fast Tracker™ - Tag Identification System (T.I.S.): For advanced field applications, the HI98703 integrates Fast Tracker™, a Tag Identification System that significantly simplifies data collection and management. This innovative feature allows users to record the exact time and location of specific measurements or series of measurements by utilizing iButton® tags placed near sampling points, streamlining your fieldwork. Each iButton® tag contains a unique computer chip encased in durable stainless steel.
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GLP Data Functionality: The HI98703 incorporates comprehensive Good Laboratory Practice (GLP) functions, ensuring full traceability of your calibration conditions. This invaluable feature records crucial data such as calibration points, date, and time, promoting data integrity and accountability.
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Extensive Data Logging: The internal memory of the HI98703 can store up to 200 measurements, providing ample capacity for your data. These logged readings can be easily recalled at any time directly from the instrument.
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Effortless Data Transfer: For further data storage, analysis, or record-keeping, all logged data can be seamlessly downloaded to a Windows-compatible PC. This transfer is facilitated via either the RS232 or USB port, utilizing the dedicated HI92000 software.
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Backlit LCD Display: The instrument features a clear, user-friendly backlit LCD display. This intuitive interface provides step-by-step guidance through routine operational procedures and calibration processes, ensuring ease of use even in low-light conditions.
Significance of Use
Turbidity and Water Quality: Turbidity stands as one of the most vital parameters for assessing drinking water quality. While historically viewed primarily as an aesthetic characteristic, substantial evidence now confirms that effective turbidity control is a crucial safeguard against waterborne pathogens. In natural water sources, turbidity measurements are commonly taken to evaluate overall water quality and its suitability for various aquatic organisms. Furthermore, the monitoring and treatment of wastewater were once primarily based on turbidity control, and even today, final turbidity measurements are essential for verifying compliance with stringent regulatory standards.
Understanding Turbidity as an Optical Property: Water turbidity is an optical property characterized by its ability to scatter and absorb light, rather than transmit it directly. The scattering of light as it passes through a liquid is predominantly caused by the presence of suspended solids. Consequently, higher turbidity levels correlate directly with a greater amount of scattered light. It's important to note that even highly purified liquids will exhibit some degree of light scattering, meaning a true "zero turbidity" measurement is practically unattainable.
EPA Reporting Requirements for Drinking Water: Drinking water treatment plants that source water from surface water bodies (such as lakes and rivers) are mandated by the EPA to diligently monitor and report turbidity levels. The requirements for nephelometers and measurement reporting, as outlined in EPA Method 180.1, are specific and include:
- The applicable turbidity range for reporting is 0-40 Nephelometric Turbidity Units (NTU).
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Light Source: A tungsten lamp operating at a color temperature between 2200-3000°K.
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Path Length: The combined distance traversed by incident and scattered light within the sample tube must not exceed 10 cm.
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Detector: Positioned at 90° to the incident light path (with a maximum deviation of ±30° from 90°). The detector, and any accompanying filter system, must have a spectral peak response between 400 nm and 600 nm.
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Sensitivity: The instrument's sensitivity must enable the detection of a turbidity difference of 0.02 NTU or less in waters exhibiting turbidities below 1 unit.
Reporting Requirements According to EPA Method 180.1:
| NTU reading |
Rounded to nearest |
| 0.0 - 1.0 |
0.05 |
| 1 - 10 |
0.1 |
| 10 - 40 |
1 |
| 40 - 100 |
5 |
| 100 - 400 |
10 |
| 400 - 1000 |
50 |
| > 1000 |
100 |
Compliance Statement: The HI98703 is engineered to meet and exceed all meter criteria specified by EPA Method 180.1 and Standard Methods for the Examination of Water and Wastewater 2130 B, ensuring reliable and compliant performance for your water quality analysis needs.
Principle of Operation
Understanding Turbidity Measurement: The Hanna Instruments HI98703 Portable Turbidity Meter operates on a sophisticated optical principle, where a precisely directed light beam interacts with your sample. As light passes through, it is scattered in various directions. The intensity and pattern of this scattered light are influenced by several factors, including the light's wavelength, as well as the size, shape, refractive index, and color of the particles suspended within the sample. The HI98703's advanced optical system integrates a tungsten filament lamp with both a 90-degree scattered light detector and a 180-degree transmitted light detector to capture these crucial interactions.
Ratio Turbidimetry for Enhanced Accuracy: In the ratio turbidimeter mode, the instrument's microprocessor intelligently calculates the Nephelometric Turbidity Unit (NTU) value. It does this by analyzing the signals received from both detectors, employing a smart algorithm that effectively corrects for potential interferences caused by sample color. This sophisticated optical system and measurement technique also proactively compensate for any fluctuations in the lamp's intensity, significantly reducing the need for frequent instrument calibration and ensuring consistent, reliable results.
Optimized Performance at Low Turbidity: For measurements in the non-ratio turbidimeter range, the NTU value is derived solely from the signal detected at the 90-degree scattered light detector. While this method offers exceptional linearity for lower turbidity ranges, it is more susceptible to variations in lamp intensity. Crucially, the detection limit of any turbidimeter is determined by the amount of "stray light"—light detected by the sensors not originating from suspended particles. The HI98703's optical system is meticulously engineered to minimize stray light, enabling it to deliver highly accurate and dependable results even for very low turbidity samples.
