The HI7660-28 are nephelometric turbidity probes designed for use with Hanna Instruments® HI510 or HI520 Universal Process Controller. The system is designed to measure low turbidity values according to the nephelometric method (ISO 7027 – EN 27027). An integral temperature sensor measures water temperature and adjusts the probe signal for temperature-related changes over the range of 0 to 50 °C (32 to 122 °F). The controller displays both measurements simultaneously. Turbidity is a key indicator of water quality and effectiveness of water filtration. The system is suitable for applications in drinking water, municipal and industrial water treatment, desalination and water quality monitoring. The majority of low-measurement applications using the HI7660-28 probe require installation in a pressurized flow cell. The HI7676602 flow cell is designed to eliminate ambient light effects and maintain sample pressure inside the flow cell. This minimizes sample out-gassing, a common problem in many turbidity systems that can cause measurement errors.

• Digital probe stores model, firmware version, and serial number.
• Built-in temperature sensor for measurement and compensation.
• Stored calibration data includes: calibration date and time, turbidity calibration standard, offset, and slope.
• ISO 7027 sensors use a near infrared light-emitting diode (LED) to eliminate color interference.
• Factory calibrated turbidity probe.
• Adheres to ISO 7027 – EN 27027 standards.

Principle of operation

Turbidity is a term that defines the opaqueness or cloudiness of water.
The HI7660-28 are optical probes that follow ISO 7027 – EN 27027 standards.
The unit of measure is FNU.
A light beam from an infrared source is sent through an optical window of the probe into the sample.
The light is scattered by suspended particles in the sample. The 90° scattered light is reflected through a second window where it is converted to an electrical signal proportional to the turbidity of the standard or sample.