Azbil KFDB, Руководство пользователя

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17
Chapter 4. CALIBRATION AND ADJUSTMENT OF
TRANSMITTER SECTION
4-1. General
The detector section (meter body section) generates with its torque tube a torque which
is proportional to the measured process variable. The generated torque is conveyed to the
transmitting mechanism of the transmitter. Therefore, regardless of the type of the detector
used in conjunction, the transmitter section should be adjusted so that it transmits a linear
output of 20 to 100 kPa {0.2 to 1.0 kgf/cm
2
} for 1 to 100 % of the measuring range.
If the instrument is incorporated with the elevation/suppression provision, remove the
spring assembly so that the instrument can be calibrated in the state that has no elevation or
suppression and that its zero point is not shifted.
For instrument operation check or calibration or for instrument adjustment after replacing
its detectors or ranges, connect a precision pressure meters of 0 to approximately 150 kPa {1.5
kgf/cm
2
} to the EXT SP connection port of the instrument.
4-2. Calibration of Differential Pressure Transmitter
(1) Release the low pressure connection port (marked L) to atmosphere.
(2) Connect to the high pressure connection port (marked H) a variable pressure source (such
as the air supply via a regulator) corresponding to the measuring range and a precision
pressure gauge covering the measuring range. (For a flange type meter body, prepare a
piping adaptor.)
(3) Apply to the high pressure connection port a pressure corresponding to 100 % of the
measuring range by adjusting the variable pressure source.
(4) If the output pressure is largely shifted from 100 % (100 kPa {1.0 kgf/cm
2
}), adjust the
SPAN CHANGE boss using a plain screwdriver so that the output pressure becomes
approximately 100 %. As you turn the boss clockwise, the output pressure rises and the
span becomes narrower. As you turn the boss counterclockwise, the output pressure falls
and the span becomes wider.
(5) Release the high pressure connection port to atmosphere.
(6) If the output pressure is shifted from 0 % (20 kPa {0.2 kgf/cm
2
}), adjust the ZERO ADJ
screw so that the output pressure becomes 0 %. As you turn the screw clockwise, the
output pressure rises, and vice versa.