Precautions For Calibration - horiba TW-150 Instruction Manual

4.2

Precautions for Calibration

Follow the correct order for calibration
Perform calibration in the following order. Common zero calibration → pH → color → turbidity
→ conductivity (optional) → residual chlorine.
Calibrating pH after color may cause measurement unstableness and calibration failure.
Remove the residual-chlorine sensor before performing span calibration for color.
When performing span calibration for color, remove the residual-chlorine sensor and attach
the provided rubber plug. Span calibration solution for color affects the residual-chlorine
sensor.
Adjustment calibration using sample water
The relevant calibration coefficient for each measurement item may be a zero-calibration
coefficient or span-calibration coefficient depending on the item. After calibration, the target
calibration value is updated and the previous result is kept for the other calibration value.
Measurement
items
Turbidity
Color
Residual
chlorine
Water
pressure
pH
Conductivity
Water
temperature
Calibration alarms
If a calibration value goes beyond a specified range, an alarm occurs and calibration is not
updated. The previous calibration value continues to be used.
Tips for flow rate adjustment
Quickly adjust the flow rate after calibration. If flow rate adjustment is delayed, calibration

solution in the calibration tank may dry up during calibration.
The flow rate changes when running calibration solution at calibration starting from when

running sample water after calibration. Flow rate adjustment is required for each time.
In calibration using the calibration tank, if there are air bubbles in the pipe causing poor

flow of calibration solution, fully open the valve and raise the calibration tank to smooth
the flow. After confirming that the flow is stable, make sure to adjust the flow rate.
Do not touch calibration solution.
When disconnecting the calibration tank from the calibration inlet after calibration, wear
protective equipment, such as gloves to avoid direct contact with the solution.
Dispose of used fluid according to local laws.
After calibration, obtain used fluid, such as span calibration solution including the fluid
remaining in the pipe in the used fluid tank and dispose of it according to the appropriate laws,
such as the sewerage law.
pH 9 calibration solution is alkaline and color calibration solution (chloroplatinic acid) contains
cobalt heavy metal and is strongly acidic. Special care is required for proper disposal.
Target calibration value
Zero calibration value
Zero calibration value
Span calibration value
Zero calibration value
Zero calibration value
Span calibration value
Zero calibration value
Remarks
When automatic zero calibration is set, the zero
calibration coefficient is updated if automatic zero
calibration is executed.
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4 CALIBRATION
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