4-9
Chapter 4 Maintenance and Troubleshooting of this Device
4-2 Calibration of the Setting Range and Output Signal
This section describes calibration work which is performed at our company and at designated
service stations. Since precise reference input devices and measuring instruments are necessary, this
is not work that will typically be carried out by users, but it is described in case it absolutely must be
performed.
As shown below, there are two types of calibration.
• Setting range calibration (input calibration) using a reference input device
• Output signal calibration
4-2-1 Setting Range Calibration Using a Reference Input Device
(1) Preparation
The method for calibrating the lower range value (LRV) and upper range value (URV) of the
setting range by inputting a reference pressure into the device is described below. First calibrate the
lower range value, and then the upper range value.
(2) Device to Use
For this calibration, have the following devices available. The required performance specifications
for each device are provided for reference. It is desirable for the uncertainty of the measuring device
to be at least four times the accuracy of the transmitter to be calibrated.
• Standard pressure generator:
One that can generate pressures in the measurement range of the device
Accuracy: ±0.025% rdg.
• Power supply: 24 V DC
• Precision resistor: 250 Ω ± 0.005%
• Voltmeter: 10 V DC range ± 0.02% + 1 digit
• Communicator: CommStaff, HART communicator
(3) Caution
The accuracy of this device after calibration depends on the performance specifications of the
device used here.
(4) Calibration Conditions
Perform real pressure calibration under the following environmental conditions.
• Perform calibration in a windless test chamber. If there is a wind, pressure will be applied to the
pressure-receiving part on the side that is open to the atmosphere, which may exert an effect on
calibration accuracy.
• Standard operating temperature of 23 °C, humidity of 65%. Provided that there is no rapid
fluctuation, there will not be any significant effects even if the temperature is in the 15 to 35 °C
range, or if humidity is in the 45 to 75% range.
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