Azbil Corporation
Model
KFPA
,
KFTA
- Field Mount type Pressure Indicating Controllers
21
5-2: Controller mechanism
5-2-1: Balance adjustment for controller proportional band
First, remove the dial stopper by loosening its screw.
(1) Set the proportional band at 500%.
(2) Set the set point pointer and the measuring pointer at 50%
(3) With the reset dial set in the full open state (minimum reset time), set the output air
pressure at 50% F.S. (59.1 kPa {443 mmHg}) by adjusting the set point pointer.
(4) When the output pressure is stabilized, fully close (maximum reset time) the reset
dial and move booth pointer to the 50% position.
(5) So adjust the length of the deviation link that the difference of output pressures
between when the proportional band dial is set at 20% (INC. MEAS. INC. OUT)
and at 20% (INC. MEAS. DEC. OUT) is not greater than 0.8 kPa {6 mmHg}.
(6) Adjust the flapper adjusting pin so that the change in the output pressure becomes
less than 0.8 kPa {6 mmHg} when the proportional band is changed from 20% to
500%. (Turn the adjusting pin clockwise if the output increases when the band is
changed from 20% to 500%.)
(7) Adjust the feedback link adjusting pin so that the output pressure becomes 59.1 +
0.3 kPa {443 + 2 mmHg} at 500% proportional band. (The pressure increases as
the pin is turned clockwise.)
(8) Repeat step (5), (6) and (7) so that, in the entire range of the proportional band, the
output pressure becomes 59.1 + 1.2 kPa {443 + 9 mmHg} in the range of white
figures 50 to 500 to yellow figure 50; and 59.1 + 2.4 kPa {443 + 18 mmHg} in the
other range.
~Note
1: With step (4), pneumatic pressure of about 59.1 kPa {443 mmHg} is
sealed in the controller reset chamber. Since the pressure may change
in a prolonged time, complete the above operations as rapidly as
possible.
2: For change between INC. MEAS. INC. OUT (direct action) and INC.
MEAS. DEC. OUT (reverse action), free the dial stopper by loosening
its clamping screw, turn the dial to the opposite action range, and then
fix the dial stopper.
