HF Scientific Turbidimeter Support

Turbidimeter manual

Importance of Getting the Detailed Data

The MicroTOL Turbidimeter manufactured by HF Scientific is used to monitor the influent and effluent turbidities of the laboratory flocculator setup. In the current experimental setup, we are sampling turbidity measurements from each turbidimeter in 1 second intervals using Process Controller.

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By looking at the analog voltage data, we can decide how to filter the data in a way that will minimize background noise but give us good temporal resolution of the change in turbidity in the sample volume. We should be able to draw better conclusions about particle size and sedimentation velocities this way than from the analyses using averaged data. We are currently in contact with HF Scientific to determine how to obtain this analog data.

Contact Log with HF Scientific, Inc. Technical Support

Friday, February 15th

Gemma talked with Phil/Joel in technical support. It is possible to get the "Raw Data" and we can do this by incorporating MODBUS communication programs. Phil does not know the exact timing of the analog signal, but he believes that is as low as 250 milliseconds (maybe even lower), however, he also said that we might not be able to get a clear enough (readable) signal until we reach 750 milliseconds. He will figure out the exact number and respond next week.

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The other method that we discussed was to log the data via modbus. We use a program called Modbus Poll. I have provided the link below. The cost is $99 for a single license, but it is free fro a limited period, I'm not sure how long that period is.

http://www.modbustools.com/index.asp^{Image Removed}

If anyone there knows programming and is familiar with modbus they can write something to get the data.

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If you need RS485 converters we use B & B (bb-elec.com). For RS485 to RS232 we recommend Part #485D9TB
$74.95 for RS485 to USB we recommend Part # USOTL4 $139.95.

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New Raw Data Aquisition

Cameron has outfitted the effluent turbidimeter with the ability to output raw voltage data. We need to figure out how to obtain the data on our PC and understand how to calibrate and handle the data.

LED Lamp

After it was determined that the heat produced from the IR lamp in the turbidimeter was causing recirculation currents in the settling column, the team researched into alternatives. HF Scientific sells turbidimeters with a LED lamp, a no heat producing lamp. After contacting with HF Scientific, the team found that we can simply replace the upper module of the turbidimeter with a new LED lamp. Mike from technical support reported that the LED lamp turbidimeters actually have heat added into the meter to help performance, but that he could disemble this "added heat" function before shipping the module to us.

A recent comparison between IR and tungsten lamp turbidimeters concluded "Turbidimeters with spectral peak responses of the detection systems between 400 and 600 nm give most often lower readings than instruments that complies with ISO 7027 Section 3. Samples coloured by dissolved humic acid give lower readings than corresponding, less coloured ones, especially with instruments that operate in the wavelength range of visible light. For natural waters and suspensions other than formazine, the variation in light scattering properties of suspended particles had various effects in turbidimeters that do not comply with the international standard and the reductions in measured turbidity
were often much larger than those caused by colour. The results of our testing were confirmed in an interlaboratory comparison where two samples were measured by 81 laboratories with various instrumentation."

The new module will ship in May. After installation during the summer 2008, the new setup to prevent premature settling and to prevent recirculation currents in the settling column will be ready and new experimentation can occur.

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