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201/203/205/207 Series Flowmeters and Controllers Instruction Manual
2.7.4.
Response to Command Changes
The response of the valve control circuit to command signal changes is set at the factory for a fast and
stable response. The default configuration is the fastest response to command changes and allows some
overshoot and undershoot in the actual flow rate while the control circuit is establishing the new
command point. If excessive overshoot is present and not desirable, the response can be slowed by
removing the jumper labeled J15 for 15 V boards or for 24 V boards, the jumper across the bottom two
pins of J8 (see images in section 2.7.3 above). This setup results in no overshoot or undershoot in the
actual flow rate as the controller circuit establishes control at the new command point. This jumper does
not affect the system gain and will not dampen out oscillations. To adjust the response, you need a
means of producing a step change in the command voltage from 10% of full scale to 100% of full scale.
Follow the steps outlined below:
1) Cover J15 (bottom two pins of J8 for 24 V boards) with a jumper.
2) Set the command voltage to 10% of full scale and allow the flow to stabilize.
3) Step change the command voltage to 100% and observe the flow through the controller.
If the overshoot is tolerable, make no further changes. Else, remove the jumper and to prevent losing
the unused jumper, place it over only one pin of J15 (one of the pins of J8 for 24 V boards).
Range Changing
The range of the flow controller can be changed in the field if recalibration facilities are available. The flow
controller may require a different orifice, which can be purchased separately from the factory. A listing of the
orifices available can be found in Section 3.7. A brief description of the steps needed to adjust the flow range
of a Hastings flow instrument can be found in Section 3.3.
NOTICE: It is strongly recommended that adjustments to the span/calibration of a Hastings flow
instrument be made by Hastings personnel with the appropriate equipment and training. Improper
adjustments to the flow instruments will result in inaccurate data and poor instrument function.
Valve-Override Control
The valve override control line (pin 8 on 15 V boards, pin 6 on 24 V boards) provides a method to override the
valve open or closed regardless of the flow or command signals. During normal operation this line must be
allowed to float freely (no voltage source connected). This will allow the loop control to open and close the
valve as it requires to meet the issued setpoint. If the valve override line is forced high (> +10 Volts) the valve
will be forced full open. If the valve-override line is forced negative (< 0 Volts) the valve will be forced closed.
EAR99 Technology Subject to Restrictions Contained on the Cover Page
Page 19 of 28
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