HF scientific Micro1000 Laboratory Turbidimeter - 0-10,000 NTU - Manual (Page 16)

Rev. 3.2 10
1. Slowly rotate the calibration standard one complete revolution (360°). While rotating the
standard, observe the measured turbidity and locate the position of the cuvette having the lowest
turbidity reading.
2. With the calibration standard positioned at the location having the lowest turbidity reading,
install the Indexing Ring over the black light shield on the standard so that the pointer of the
Ring faces forward, toward the operator.
When using the standards in the future, always insert the standard so that the pointer of the index
ring faces forward. Slowly rotate the standard back and forth about 5° to find the lowest point. The
standard is now indexed and ready to use.
5.3. Calibrating the Instrument
Even though it is possible to calibrate the instrument using any sequence of the prescribed
calibration standards, to achieve the stated accuracy you must use the procedure below to calibrate
the instrument.
1. Select the calibration function of the instrument by pressing either the up or down arrow key
until the “Cal” block is lit. Press the key. The cal block will now be lit and the turbidity
displayed in the lower row of the display should read 0.02 NTU. This is the first standard that
must be used in calibration.
2. Insert the 0.02 NTU calibration standard into the sample well and index the standard if you have
not already done so (see section 5.2). At this point press the key to initiate calibration on the
0.02 NTU standard. The instrument will calibrate on the 0.02 NTU level (the “Cal” block and
the “Store” block will flash on and off for a period of time and you will see a countdown from
90).
Note: The 0.02 NTU standard must be evaluated in calibration at both the start and end of calibration
to ensure accurate measurements in the ratio mode and when recording FAU measurements.