User Manual

Span Your Valves
Chapter 9
9-39
9. Observe and record actual backpressures reported by the QDC
module for all profile segments in PPS10, 14, 18, 22, 26, 30, 34 etc.
(N44:714, 718, 722, 726, 730, 734, 738, 742, 746, 750, 754).
10. Compare actual backpressures with your setpoints in
PPC10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50 as follows:
If Then
Actuals are greater than
setpoints by 20% or more
1. Decrease PLC44 by 10%.
2. Enter this new value into PLC data table.
3. Repeat the profile with steps 79.
4. Repeat these adjustments until actuals
just drop below setpoints.
Actuals are less than
setpoints by 20% or more
1. Increase PLC44 by 10%.
2. Enter this new value into PLC data table.
3. Repeat the profile with steps 79.
4. Repeat these adjustments until actuals
are equal to or greater than setpoints.
Actuals are less than
setpoints by 20% and PLC44 = 100%
1. Decrease PLC42 by 10%.
2. Enter this new value into PLC data table.
3. Repeat the profile with steps 79.
4. Repeat these adjustments until actuals
are equal to or greater than setpoints.
Test Valve Linearity with a Plastication Backpressure Profile
1. Change backpressure setpoints to 1/2 PLC44 (1/2 Max Control Limit)
in PPC10, 14, 18, 22, 26, 30, 34, 38, 42, 46, and 50
(in N44:426, 430, 434, 438, 442, 446, 450, 454, 458, 462, 466).
2. Download the PLC and PPC blocks to the QDC module.
Important: If downloading from your programming terminal, download
PLC followed by PPC with download bits B21/13 and 14 (chapter 4).
3. Run an open-loop backpressure vs. position profile. Do this by
toggling DYC02-B08 (B34/408) from 0 to 1 to 0.
4. Compare backpressures reported in middle segments 5, 6, and 7 in
PPS26, 30, 34 (N44:730, 734, 738) with setpoints PLC26, 30, and 34.
Adjust PLC41 or PLC43 as follows:
If actual backpressures are: And Your Selected
Valve is:
Then change PLC41 or 43
(N44:397 or 399) as follows:
Greater than or equal to setpoints Either one Increase PLC41 in 5% steps
Less than setpoints Direct Acting Increase PLC43 n 5% steps
Reverse Acting Decrease PLC43 in 5% steps