This instruction is copied from the User Manual:

5.10 Slurry calibration

The conditions in our lab will be different from the conditions in the field. Therefore, an initial calibration is needed. After performing the water calibration:

·         Apply high dense slurry until a stable measurement of SG is given. Calibrate the density as well on this slurry, following the next steps.

a)       Obtain a representative grab sample of the slurry in the line and to weigh it accurately. This sample has to be exactly 1 liter and is best to be drawn from a sample point in a vertical part of the line where the sample is already homogeneously mixed. A 1L slurry grab sample beaker is preferred but if this is not available then a standard lab beaker of over 2L can be used. Please note: It is important to weigh the dry empty beaker before the sample is drawn since this weight has to be deducted from the total weight once the sample is drawn. Fill the glass beaker between 1 and 2 L. Make sure you do not need to drain, after filling the beaker. In 2025, Arenal will issue a new digital weight scale with the possibility to use any size of flask/beaker.

b)      The next step is to weigh the grab sample with an accurate electronic scale with at least a 1 gram readout. If needed, deduct the weight of the empty beaker. Divide the measured weight by the volume of the sample in the beaker.

c)       Once the result is known, the actual Slurry Calibration can be done.

d)      To calibrate one of the four parameters, press the corresponding grey box. However, always start with calibrating the SG / density (and also first the water calibration).

e)      Like with the Water Calibration, press the SG or Density Box on the front screen.

 

f)        After pressing the SG or density box, the above picture pops up.

g)    Calibration is done with a linear function between the Process Water Calibration (Zero) and a high density slurry (Span). This “span” is based on the value that the sensor generates from its physical model. This “Model value” shall be calibrated to the value that the Laboratory determined, the Lab value. When taking a sample, register the Model value on paper. Then after determining the Lab value, enter both values in the corresponding field. Press Save.

The initial setting for fine sand is:  Model=1200.0    Lab=1630.0

These settings for specific applications are equal all over the world, because it is physically related to the measurement. However, smaller particles have a smaller span

h)      Save the new settings by pressing on the “Stiffy Icon”   at the bottom of the screen.

The system is now calibrated with a new factor to the exact same value as the grab sample and is back online.

For immediate slurry calibrations, when the slurry is stable, press Calibration Help button, see picture above. 

 When the process is stable, and a sample is taken, press Calibrate. Just enter the new reading of the lab and the system automatically saves the Model value at the correct place.

The other parameters can be calibrated in a similar manner by pressing the corresponding box. The Slurry Calibration of TSS is slightly different. The percentage is set from 0 to 100%. The TSS can only be calculated when the density of the solids is entered and saved.

·    From time to time or after some part was replaced a Slurry Calibration may be necessary to compare the measurement with the lab results. It is at this stage assumed that all other set-up parameters such as measuring ranges, polynomials and output settings etc. are still the same as when the system was originally commissioned. In case these parameters have changed or need adjustment for whatever reason, please get in touch with Arenal’s support team. The Slurry Calibration corrects the density reading and can be done online within a few minutes. There is no need to switch the system off or to remove any parts from the line.

·         The best way to do multi-point slurry calibration is to follow the next steps.

a.    Set Moving average to 1.

b.    Start the logger on a frequency of 1 Hz. The logger contains raw measurement data and results from its original model, as well as the calibrated values. With the logging file Arenal can assist you with increasing the accuracy of your calibration.

c.    Pump process water through the line at the same temperature as the slurry temperature. Keep it running for at least 20 minutes. The laboratory value of process water (“Lab Value/Low”) shall be 1.000. Enter the “Result from Model” in the box “Online Value/Low”.

d.    Pump high dense slurry through the line. After 15 minutes, press the Erlenmeyer  button on the bottom.

d.1. Press “Start” just before taking the sample from the process.

d.2. Press “Stop” just after taking a sample from the process.

d.3. Write down ID number

d.4. This ID number is written down in the logging file.

e.    Repeat [3] several times for different slurry densities. Present the data in a xy graph in Excel to determine the best fit for the new calibration. Take a high point on this fit and add this point to the “high” calibration. SAVE.

f.     If you have any questions, ask Arenal for assistance.

 

Each second a new value is presented. If this interval frequency is not needed, one may choose to increase the moving average.

The Result from Model shows the value before this calibration.

Example multi-point calibration
Sample ID	Date	Time	Online value "Model"	Lab Value
			1	1
1	18-apr	9:00	1,567	1,520
2	18-apr	11:30	1,468	1,500
3	18-apr	14:00	1,124	1,150
4	19-apr	9:30	1,645	1,600
5	19-apr	11:00	1,345	1,300
6	19-apr	13:30	1,863	1,750
	Fictive high point calibration:
	Online	2,0000
	Lab	1,9538	(=0,9769 * online value)

 

In case of the slurry properties are temperature sensitive, perform a Temperature Sensitive Slurry Correction.

When a temperature drift appears to be present, after all previous calibrations, proceed as follows:

a)       Press the “SG” box, login and press “Water Calibration”. Make a screenshot ( ).

b)      Remove USB stick by Pressing ( ) and “Remove USB Stick”

c)       Send a complete copy of the data on the USB stick to the Arenal service team (service@arenal-pcs.com) by www.WeTranfer.com and add the data from the laboratory measurements (indicating date, time and SG) as well.

d)      Arenal service team will send you temperature correction coefficients, see below in the table. Press the “Temperature” box.

e)      Enter the given value for “Temperature Correction Coefficient”.

f)        Press the stiffy icon to SAVE and save to USB.

g)       It is expected that a new slurry Slurry Calibration needs to be done. We made an initial suggestion in the table above.