Key Features:

• AMCO AEPA-1 Primary Turbidity Standard: The AMCO AEPA-1 standards, recognized by the USEPA as a primary standard, are provided for the HI93102's turbidity range. These non-toxic standards are crafted from uniform styrene divinylbenzene polymer spheres, ensuring stability, reusability, and extended shelf life for reliable calibration.
• Data Logging: The HI93102 enables logging of up to 25 measurement readings. These logs are easily retrievable at the press of a button, and a convenient reminder notifies the user when memory capacity is full. The logging function can be activated or deactivated as needed.
• GLP Compliance: A dedicated "GLP" button provides instant access to Good Laboratory Practice information, including the date, time, and two calibration values for the current measurement mode, ensuring traceability of results.
• Auto-Shut Off: Conserve battery life with selectable auto-shut off options after 10, 20, 30, 40, 50, or 60 minutes of inactivity while the meter is in measurement mode, preventing accidental power drain.
• Battery Status Indicator: The meter continuously monitors battery status during each measurement cycle. A clear indicator warns the user when the remaining battery life is insufficient for reliable measurements, ensuring consistent performance.
• Diagnostic Error Codes: Helpful diagnostic error codes appear on the display to alert users to various issues, such as low light, high light, or samples outside the measurable range, facilitating efficient troubleshooting.

Significance of Use

Monitoring turbidity, free and total chlorine, cyanuric acid, pH, iodine, bromine, and low-range iron are all crucial for maintaining optimal water quality across diverse applications, including drinking water, wastewater treatment, and recreational water bodies like pools and spas.

Turbidity stands as one of the most critical parameters for assessing drinking water quality. Historically viewed primarily for its aesthetic impact, substantial evidence now confirms that effective turbidity control serves as a robust safeguard against harmful pathogens. In natural aquatic environments, turbidity measurements are essential for gauging overall water quality and determining its suitability for various aquatic organisms.

Chlorine is widely recognized as a primary disinfectant in water treatment, commonly added in forms such as calcium hypochlorite, sodium hypochlorite, or even chlorine gas. Upon introduction to water, chlorine forms hypochlorous acid (HOCl), which then dissociates into hypochlorite ion (OCl^-).

HOCl ⇌ H⁺ + OCl^-

HOCl represents the more potent disinfectant form of chlorine compared to OCl^-. To ensure the effectiveness of added chlorine, careful consideration of the water's pH is vital. At approximately pH 7.5, HOCl and OCl^- exist in roughly equal concentrations. Below pH 7.5, the equilibrium shifts to favor HOCl, while above pH 7.5, the shift favors OCl^-. Therefore, for effective disinfection, chlorine addition is most impactful when the water maintains a neutral or slightly acidic pH.

Initially, when chlorine is introduced into water, it exists as free chlorine, which indicates the amount readily available for disinfection. As chlorine performs its sanitizing action against bacteria and pathogens, it transforms into combined chlorine, which no longer functions as a disinfectant. The measurement of total chlorine encompasses both free and combined chlorine. By analyzing both free and total chlorine levels, water operators and pool owners can precisely determine if sufficient chlorine is present for effective disinfection.

Cyanuric acid is primarily known for its role as a chlorine stabilizing agent, widely employed in swimming pool and spa treatment programs to retard the decomposition of hypochlorous acid. In outdoor pool environments, UV radiation significantly accelerates this decomposition. When applied correctly, cyanuric acid can lead to up to an 80% reduction in typical chlorine consumption during peak usage months.

Bromine, being less volatile and more stable than chlorine, serves as an excellent disinfectant choice for pools, spas, hot tubs, and as a sanitizing agent in drinking water systems. However, similar to chlorine, excessive bromine concentrations in water can pose health risks and cause eye irritation. Daily monitoring of bromine levels is crucial to prevent equipment damage, optimize process efficiency, and significantly enhance user safety.

Iron is naturally present in water at low concentrations but can reach elevated levels in wastewater effluents. Monitoring iron concentration in water is essential because it can become harmful above certain thresholds. In domestic water, for example, high iron levels can stain laundry, damage kitchenware, foster the growth of specific bacteria, and impart an unpleasant taste to the water. Additionally, iron often indicates ongoing corrosion in water cooling and heating systems. Furthermore, iron levels are routinely monitored in mining wastewater to prevent environmental contamination.

Principle of Operation: Turbidity Measurement

During turbidity measurement, the light beam traversing the sample is scattered in multiple directions. The intensity and pattern of this scattered light are influenced by various factors, including the wavelength of the incident light, the size and shape of particles, refractive index, and inherent color of the sample. The sophisticated optical system of the HI93102 incorporates an LED light source and a precisely positioned 90° scattered light detector to accurately quantify turbidity.

Principle of Operation: Colorimetric Mode

When measuring specific ions in colorimetric mode, a parameter-specific reagent is introduced to the sample, inducing a distinct color change where the intensity of the color correlates directly with the concentration of the substance. This color change is then analyzed colorimetrically in accordance with the Beer-Lambert Law, which states that light is absorbed by a complementary color, and the emitted radiation is proportional to the concentration. For accurate determination of free and total chlorine, cyanuric acid, pH, iodine, bromine, and low-range iron, the instrument utilizes a narrow band interference filter at 525 nm (green). This filter selectively allows only green light to reach the silicon photodetector, effectively blocking all other visible light from the source. As the color change in the reacted sample becomes more pronounced due to increasing concentration, the absorbance of the specific green wavelength simultaneously increases, resulting in a corresponding decrease in light transmittance.