NEP160 User Manual
Copyright
–
2000 - 2011
Specifications subject to change without notice.
Page 15 of 24
F1.3 Calibration - 3 point
A three-point calibration is recommended when operating the ANALITE NEP160 over a wide range (say 0 to
10,000NTU) or where exceptional linearity is demanded over a nominal range (say 0 to 100NTU). For purposes of
example only, we are using 50NTU and 100NTU as the calibration reference solutions when explaining the three-point
calibration procedure below. Normal practice would be to select a second point value at the anticipated values of
measurement and the third point of calibration being the highest measurement value anticipated (or a little higher).
1
Connect the desired Probe to the ANALITE NEP160 Turbidity Meter
2
Press the
ON
button to power the ANALITE NEP160 ON.
3
Select the Setup menu by pressing
Menu
and then
F1
.
Cal
4
Select
F3
to select the 3 point calibration
.(F3:3pnt)
5
Place the Probe into the 0NTU standard reference solution.
The display should now look like this:
x.xxNTU pnt1/3
(where x.xx is a low number)
Wait until the reading settles, then “grab” the zero reference by pressing
F2
(F2:grab)
Comment:
The NEP160 assumes that the first point of calibration is always ZERO NTU.
6
The display should now look like this:
0.00NTU pnt1/3
Press the
F2
button to accept and store the zero value and move to the second calibration point
(F2:OK)
Comment:
When the F2 button is pressed it is normal for the display to return to the original reading,
i.e. not zero.
7
Remove the Probe from the 0NTU solution and dry the Probe.
8
Place the probe into a known turbidity standard solution (e.g. 50NTU)
The display will now look like this:
xx.xNTU pnt2/3
where xx.x is normally a value near to 50.
Wait until the reading settles, then “grab” the stabilized value by pressing
F2
(F2:grab)
9
The display will now look like this:
xx.xNTU pnt2/3
10
Use the
buttons to adjust the displayed reading to match the solution value reading e.g. 50.
11
With the display adjusted press
F2
to accept and store the reading and move to the third calibration
point.
Comment:
When F2 is pressed the display will return to the original NTU reading.
12
Remove the Probe from the 50NTU solution, wash in de-ionized water and dry.
13
Place the probe into a known turbidity standard solution (e.g. 100NTU)
The display will now look like this:
xx.xNTU pnt3/3
where xx.x is normally a value near to the value of the turbidity standard
solution e.g.100.
Wait until the reading settles, then “grab” the stabilized value by pressing
F2
(F2:grab)
14
The display will now look like this:
xx.xNTU pnt3/3
15
Use the
buttons to adjust the displayed reading to match the solution value reading e.g. 100.
16
With the display adjusted press
F2
to accept and store the reading and exit calibration.
Comment:
When F2 is pressed the display will return to the calibrated NTU reading e.g. typically
100±1NTU.
17
Remove the Probe from the 100NTU solution, wash in de-ionized water and dry.
18
This completes a three-point calibration.
