Watlow CLS - Manual (Page 164)

156
Appendix B: Enhanced Process Control
Ratio Control
A chemical process requires a formula of two parts Water (H
2
O) to one
part Potassium Hydroxide (KOH) to produce diluted Potassium
Hydroxide. The desired flow of H
2
O is 10 gallons per second (gps), and
the KOH should be 5 gps. Each chemical has a pipe feeding a common
pipe. The flow rate of each feeder pipe is measured and supplied to a
4CLS, with H
2
O flow as PV1 and KOH flow as PV2. The outputs of
loops 1 and 2 adjust motorized valves.
1) Adjust and tune Loop 1 (H
2
O) for optimal performance before
implementing the Ratio setup.
2) Switch the controller to display loop 2 (KOH), and then enter the 3-
key sequence to display the following:
Display User Input
Press Yes to setup the Ratio parameters
for loop 02.
Assign loop 01 to be the master loop.
Press Enter.
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
SETUP LOOP 02
RATIO CONTROL?
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
02 RATIO CONTROL
MSTR LOOP? 01