Hanna HI93414 Offers

The instrument is based on a state-of-the-art optical system which provides accurate results by minimizing stray light and color interferences. Periodic calibration with the supplied standards compensates for any variations in intensity of the tungsten lamp. The colorimeter portion of the meter uses a 525 nm narrow band interference filter for maintaining the proper wavelength in the measurement of free and total chlorine. All measurements are performed with 25 mm round cuvettes composed of special optical glass to ensure maximum repeatability of turbidity and chlorine measurements.

Turbidity is one of the most important parameters used to determine the quality of drinking water. Once considered as a mostly aesthetic characteristic of drinking water, signi˜ficant evidence exists that controlling turbidity is a competent safeguard against pathogens. In natural water, turbidity measurements are taken to gauge general water quality and its compatibility in applications involving aquatic organisms. The monitoring and treatment or wastewater was once solely based on the control of turbidity. Currently, the measurement of turbidity at the end of the wastewater treatment process is necessary to verify that the values are within regulatory standards.

Turbidity of water is an optical property that causes light to be scattered and absorbed, rather than transmitted. The scattering of light that passes through a liquid is primarily caused by the suspended solids present. The higher the turbidity, the greater the amount of scattered light. Even a very pure liquid will scatter light to a certain degree, as no solution will have zero turbidity.

Drinking water treatment plants that obtain water from surface water are required by the EPA to monitor and report the turbidity. Surface water sources include lakes and rivers.

Features

• Three measurement modes
• EPA compliant
• Calibration
• AMCO AEPA
• CAL Check^™
• Fast Tracker^™
• GLP data
• Data logging
• Data transfer
• Backlit display

The Requirements of the Nephelometer and Reporting Measurements are:

• The applicable range is 0 to 40 nephelometric turbidity units (NTU)
• Light source: Tungsten lamp operated at a color temperature between 2200 to 3000°K
• Distanced traversed by incident light and scattered light within the sample tube: Total not to exceed 10 cm
• Detector: centered at 90° to the incident light path and not to exceed ±30° from 90°
• The sensitivity of the instrument should permit detection of a turbidity difference of 0.02 NTU or less in waters having turbidities less than 1 unit

Principle of Operation

The light beam that passes through the sample is scattered in all directions. The intensity and pattern of the scattered light is a‰ffected by many variables, such as wavelength of the incident light, particle size and shape, refractive index, and color. The optical system of the HI93414 includes a tungsten fi˜lament lamp, a scattered light detector (90°) and a transmitted light detector (180°).

In the ratio turbidimeter range, the microprocessor of the instrument calculates the NTU value from the signals that reach the two detectors by using an eff‰ective algorithm that corrects and compensates for interferences of color. The optical system and measuring technique also compensate for fluctuations in lamp intensity, minimizing the need for frequent calibration.