The HI97725 meter measures four important parameters in the treatment and disinfection of swimming pools, spas and cooling towers. HI97725 measures free and total chlorine, pH and cyanuric acid. Each plays a very important role in the treatment of water.
Chlorine is a commonly used for its disinfection properties. The effectiveness of the free chlorine is pH dependent. As pH decreases less than 7.4 the chlorine is found as hypochlorous acid and when pH increases above 7.4, chlorine is predominantly in the hypochlorite ion form. Hypochlorous acid is 100X more effective at killing bacteria than hypochlorite. The chlorine method is an adaptation of the US EPA Method 330.5, DPD Colorimetric Method while the pH is an adaptation of the Phenol Red Method. For chlorine and pH, when the appropriate reagent is added to the sample, is a color change will occur. The greater the concentration, the deeper the color.
Up to 90% of the chlorine can be broken down by sunlight in a matter of hours. Adding cyanuric acid to the water stabilizes the chlorine which will slow down the breakdown process. The cyanuric acid is measured by a turbidimetric method. For cyanuric acid the cloudiness of the sample is dependent on the concentration. The associated color/turbidity change is colorimetrically analyzed according to the Beer-Lambert Law. This principle states that light is absorbed by a complementary color, and the emitted radiation is dependent upon concentration.
For determination of all four parameters, a narrow band interference filter at 525 nm allows only green light to be detected by the silicon photodetector and omits all other visible light emitted from the LED lamp. As the change in color/turbidity of the reacted sample increases, absorbance of the specific wavelength of light also increases, while transmittance decreases.
- LED that generates very little heat.
- 8 nm narrowband interference filter that is accurate to ±1 nm.
- Reference detector that modulates the voltage to LED for consistent light output.
- A concave focusing lens that reduces errors from imperfections in the cuvette.
On-Screen Features
CAL Check
Advanced features including CAL-Check to verify performance and if necessary, recalibrate.
Setup Options
Backlit dot matrix LCD that offers an exceptionally intuitive user interface that is easy to read and understand.
Tutorial Mode
Tutorial mode for step-by-step instructions to guide a first-time user in how to perform a measurement correctly.
Reaction Timer
Built-in reaction timer that ensures consistency amongst multiple users.
HI97725 FEATURES/BENEFITS:
Stable Light Source:
- The internal reference system of the HI97725 photometer compensates for any drifts due to power fluctuations or ambient temperature changes. With a stable source of light the readings are fast and stable between your blank (zero) measurement and sample measurement.
High Efficiency Light Source:
- LED light sources offer superior performance compared to tungsten lamps. LEDs have a much higher luminous efficiency, providing more light while using less power. They also produce little heat, which could otherwise affect electronic stability.
High Quality Filters:
- Improved optical filters ensure greater wavelength accuracy and allow a brighter, stronger signal to be received. The end result is higher measurement stability and less wavelength error.
Greater Light Yield:
- A focusing lens collects all of the light that exits the cuvette, eliminating errors from imperfections and scratches that may be present in the glass. The use of the convex lens reduces the need for indexing cuvettes.
CAL Check Functionality:
- Hanna’s exclusive CAL Check feature allows for performance verification and calibration of the meter using NIST traceable standards. Our CAL Check standard vials are developed to simulate a specific absorbance value at each wavelength to verify the accuracy of subsequent readings.
Large Cuvette Size:
- The sample cell of the HI97725 fits a round, glass cuvette with a 25 mm path length. The relatively long path length of the sample cuvette allows the light to pass through more of the sample solution, ensuring accurate measurements even in low absorbance samples.
Intuitive Dot Matrix Display:
- The HI97725 is designed with a backlit, graphic LCD. With virtual keys, a battery status indicator, and error messages. Users will find the meter interface intuitive and easy to read. A dedicated help key provides information relating to the current meter operation, and can be used at any stage in the setup or measurement process to show contextual help.
Auto-off Protection:
- The meter uses three common AA batteries that allow for about 800 measurements to be taken. The auto-off feature automatically shuts off the meter after 15 minutes of inactivity in order conserve battery life.
