HF scientific DRT-15CE Portable Turbidimeter - Manual (Page 11)

DRT-15CE (5/10) Page 3
4.0 OPERATION AND DESCRIPTION
To operate the turbidimeter, it is first necessary to standardize the instrument.
Switch to the “10” range and place the Calibration Standard (0.02 NTU) in
the optical well.
The EPA recommends that cuvettes used for instrument calibration or sample measurement
be indexed. For quick and repeatable indexing of the Calibration Standard, an indexing
ring and locator pin are included with this instrument.
When shipped, the white locator pin is installed in the collar ring around the
optical well of your turbidimeter. The indexing ring is included in the
accessory section of this instrument.
To index your Calibration Standard, slowly rotate the Calibration Standard, at
least one complete revolution, while observing the reading, and locate the
position of the lowest reading. Without moving the Calibration Standard,
install the indexing ring over the ridged cap of the Calibration Standard such
that the arrow on the o-ring aligns with the locator pin.
When indexing the Calibration Standard in the future, simply insert the
Calibration Standard and rotate it until the arrow on the o-ring faces the
locator pin. Please note that this Calibration Standard is only indexed to the
turbidimeter for which it was aligned.
To standardize, first index the Calibration Standard as above. Then adjust
the Reference Adjust in the appropriate direction to cause the display to read
0.02 NTU. The unit is now ready for use on any range.
To make a measurement of a sample, clean one of the cuvettes and fill it to
within approximately 1/2" (12 mm) of the top with the sample to be
measured. Place the cap on the cuvette and carefully clean the outside
surface of the cuvette with a lint free wiper such as "Kimwipes". Place the
sample in the well and take the NTU reading directly from display. Select the
appropriate range for best resolution..
If the instrument has been subjected to cold (below 10 degrees Celsius) and
then brought indoors, it should be allowed to warm up before use, since
condensation may form on the various lenses. Warm up can be aided by
leaving the case open and the instrument on for approximately a half hour.