Liquid Controls WinHost Operation - Manual (Page 32)

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Multi-Point Calibration
Multi-point Calibration allows a flowmeter to be used over
a wide range of flow rates without experiencing a loss in
measurement accuracy due to the inherent shape of the
meter curve.
After determining the inaccuracy of the meter at a vari-
ety of flow rates and entering the information into the
LectroCount’s multi-point calibration table, accuracy cor-
rections are continuously made by the LectroCount based
on the measured flow rate.
There are two ways to obtain multi-point information for
a flow meter:
1. Manufacturer’s data supplied with the meter can be
entered directly.
2. The meter can be field calibrated by proving at vari-
ous flow rates.
NOTE: It is not required to enter flow rates in descend-
ing order. The LectroCount sorts the values internally
when it uses the data.
Method 1 - Manufacturer’s Data
Supplied with the Meter
Move the pointer to “Point Number” and press the EN-
TER Key to open the List Box Window for “Linearization
Point”. Move the pointer to “1” and press ENTER to ac-
cept that Linearization Point and return to SCREEN 13 -
“PRODUCT CALIBRATION”.
Move the pointer to “Flow Rate” and press enter to open
a Field Edit Window and enter the maximum flow rate
shown on the manufacturer’s data sheet and press EN-
TER.
Move the pointer to “Percent Error” and press ENTER to
open a Field Edit Window and enter the error percent-
age corresponding to the highest flow rate shown for the
meter on the manufacturer’s data sheet.
Select up to nine additional points from the
manufacturer’s data sheet to characterize the remain-
der of the meter’s accuracy curve and enter this data in
the “Flow Rate” and “Percent Error” fields, in descend-
ing order by flow rate. To enter a negative “Percent Er-
ror”, use the “-” key on the keypad.
When “Linearization Points” programming is complete,
move the pointer to “Linearization” and press ENTER to
open the a List Box Window shown below and select
APPLIED. Press the ENTER Key.
This puts the Linearization algorithm into effect. If the
error message ADJACENT POINTS OUT OF 0.25%
RANGE is displayed, APPLIED will not take effect. The
Linearization Points will need to be re-selected to en-
sure that no two adjacent points, based on flow rate, are
more than 0.25% apart in their corresponding “Percent
Error” fields.
Field prove the meter using the method described for
Single-point Calibration. Assuming the data provided by
the manufacturer is correct, it should be possible to fill a
prover at any flow rate within the linearized range and
obtain near perfect accuracy.
When SETUP is selected for Linearization Status, the
algorithm is not activated. SETUP should be used dur-
ing the calibration process. APPLIED is used after the
calibration process is completed.