Control Dir; Hoa - Walchem WDIS Series Instruction Manual

is insufficient may be installed in the line, so that if flow past the sensor stops, the controller will not
pump in chemicals based on a stagnant sample. Similarly, a level switch may be attached to prevent
control of an empty batch tank.

Control Dir

Press to change the direction of control, then use the Up and Down arrows to toggle between
ENTER
High Set Point and Low Set Point, and press
on the relay when the process value goes below the set point value (to add an oxidizer, or as a low
alarm). A high set point will turn on the relay when the process value goes over the set point value (to
add a reducing agent, or as a high alarm).

HOA

Use the Left and Right arrows to move between Hand, Off and Auto. In Hand (Manual) mode, the
output will be turned on immediately for a maximum of 10 minutes. In the Off mode, the output will
be turned off indefinitely. In the Auto mode, the output turns on and off in response to changes in the
process value relative to the set point. The letter inside the block on the status screen indicates which
mode the output is in.
LOW SET
POINT
DEAD
BAND
LOW SET
POINT
Pump Off
ppm
ZERO DEADBAND: NOT RECOMMENDED
Pump On & Off rapidly, damaging relay
ppm
to make your choice. A low set point will turn
ENTER
Pump Off
Pump On
TIME
TIME
19