WIKA IUT-11 - Manual (Page 39)

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Universal IS Pressure Transmitter UniTrans
Operation of Devices without Displays
Subject to change due to technical modifications. © Copyright WIKA Alexander Wiegand GmbH & Co. KG / Germany
WIKA Alexander Wiegand GmbH & Co. KG · Alexander-Wiegand-Str. · 63911 Klingenberg · (09372) 132 - 710 · Fax - 706 · E-mail: [email protected] · www.wika.de
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8.4 Calibration without Pressure
Determine the current reference values for the zero point and the span to be entered
in the transmitter before calibration. This is done as follows:
8.4.1 Zero Point Calibration
• Determine the hydrostatic pressure of the liquid’s surface that meets the zero point.
• Adjust this pressure in proportion to the sensor’s nominal pressure range.
• Multiply this proportion by 16 mA and add 4 mA to the result.
This produces the calculated current (value I
calc
), which is entered in the transmitter
and used to programm the zero point (0%).
Example:
A pressure transducer with 0 ... 400 mbar (nominal pressure) needs to be pro-
grammed.The liquid’s surface (with a density of 1) is 1 m above the diaphragm at the
zero point producing a pressure of 100 mbar.
This means that the device’s current value must be set to 8 mA when performing a dry
(empty) calibration.
8.4.2 Span Calibration
• Determine the hydrostatic pressure of the liquid’s surface, which corresponds to the
span end-point.
• Calculate the difference of the pressure value between span end-point and zero
point and divide this difference by the nominal pressure range of the sensor.
• Multiply this proportion by 16 mA and add 4 mA to the result.
This produces the calculated current (value I
calc
), which is entered in the transmitter
and used to program the span end-point (100%).
The measurement range between zero point and span end-point will be stored as
span.
I
calc
Zero point pressure (0%) 100 mbar
Sensors nominal pressure 400 mbar
------------------------------------------------------------------------------------------------ 16 mA 4 mA
+
⋅ 8 mA
= =
Calibration Value
calc
Calibration of zero point, without display, without pressure
Calibration Value
... to I
meas
= I
calc
... to I
meas
= I
calc
(2 sec.) (2 sec.) (2 sec.)
026-DS-GB