The Thermo Scientific™ AQUAfast™ AQ4500 Turbidimeter offers advanced features, such as dual light sources, enabling readings that comply with EPA180.1 and ISO7027 methodologies for water.
Turbidity reading can be affected by the presence of dissolved light-absorbing substances and air bubbles, which is why international and EPA standards for measurements of turbidity outlines the minimum equipment requirements to ensure filtration is optimal and produces safe drinking water.
According to EPA 180.1, ‘The presence of true color, that is the color of water which is due to dissolved substances that absorb light, will cause turbidities to be low.’ Light absorbing materials such as activated carbon in significant concentrations can also cause low readings.
Due to these variables, the EPA 180.1 and ISO 7027 standards require a white light source and an infra-red light source respectively. The AQUAfastTM AQ4500 turbidimeter has two LEDs that produce results that comply with reporting requirements for both methodologies.
The AQ4500 comes with two levels of signal averaging that are suitable both for regular use and for more extreme sample conditions. It features the unique white light LED that has built-in power output compensation to adjust for light intensity fluctuations, which results in more accurate readings.
Colour is compensated for in the white light mode through the use of detector ratio measurements. For highly coloured samples, the unit can operate in a ratio infra-red mode for maximum accuracy. Low to medium levels of colour in the sample are automatically compensated for in the various infra-red modes.
For maximum correction for colour, the infra-red ratio mode combines both ratio detection using a 90° nephelometric detector and an absorbance detector, as well as the natural colour rejection of an infra-red LED.
Data collected from the readings are logged into an internal memory, or can be sent to a printer or downloaded to a computer for easy time and date stamped results storage.
Other features of the unit include:
- Robust unit for precise field measurements
- Nephelometric and ratiometric measurements with autoranging
- Data log capacity of up to 100 data points
- IP67 waterproof
Lauren Butler is the assistant editor for Utility Magazine. She’s based in Melbourne, Australia.