Reference data
67
A span calibration bottle (optional)
Q
Use of span calibration bottles (optional)
Even if a span standard solution is not prepared, span calibration is possible in the method of
inserting a span calibration bottle in the cell that is filled with water. While the turbidity of a
span standard solution is already known, the turbidity of a span calibration bottle is not already
known. For the reference value for calibration from the next time, use the value obtained by
measuring a span calibration bottle with the turbidity meter calibrated by a span standard
solution. The reference value is printed on a label. Tested values may be attached at the time
of shipment from a manufacturer. When a turbidity meter is calibrated by a standard solution
used by the user, it becomes necessary to update the value of the span calibration bottle.
The contents of the span calibration bottle are water solutions of refined Kaolin, which contain
a trace amount of dispersant. Immediately before attaching a span calibration bottle to the
turbidity detector, shake the span calibration bottle adequately until all deposits disappear.
While the Kaolin is flowing, turbidity varies. When it stops flowing, a constant turbidity is shown
for several min. Wait for one minute until turbidity becomes stable after installation. After that,
as a rule, span-calibrate a span calibration bottle, and adjust the results to the reference value
within six min.
A span calibration bottle cannot be used in air. Be sure to attach a span calibration bottle to
the cell filled with zero water.
Turbidity of calibration bottle
Dilute 10000 mg/L of Kaolin standard solution with purified water, and put the solution in a
calibration bottle. Adjust the concentration of Kaolin to a turbiditly of about 50% to 80% the
levels of the Range, depending on the Range used. Leave about 5% air space in the
calibration bottle to make it possible to agitate the calibration bottle. When Kaolin of the same
turbidity is put in a bottle, the value of turbidity takes on a slightly lower value as compared
with the value poured into the cell.
If Formazin and Polystyrene Latex are used as reference materials for turbidity, span
calibration can be performed by putting Kaolin in a bottle. In this case, describe a measured
value obtained from Formazin or Polyethylene Latex calibration curves. Do not put diluted
Formazin in a bottle because turbidity changes.
Q
Method of attaching a span calibration bottle
Before attaching a span calibration bottle to the cell, remove all dirt from the span calibration
bottle. Fill the cell with zero calibration water. Be sure to insert a span calibration bottle to the
cell. Turbidity of a span calibration bottle is unstable, taking on a different value. Insert and
remove the span calibration bottle several times so that air bubbles do not adhere to the span
calibration bottle. Push the span calibration bottle into the cell toward the orientation
positioned using a pin.
Calibration jig
Calibration bottle
Liquid for which Kaolin
concentration has been
adjusted
