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Chemical Addition System Controls
Control Strategies PIDs
 Chemical System Control Modes Sodium Hypochlorite
Other Chemicals
Chemical Addition System
The speed of the chemical feed pumps is automatically flow paced to the plant effluent flow rate in order to maintain the desired chemical dosage. The chemical systems are controlled through LP2001, which is located in a walk-in enclosure just south of the Blower Building.
Startup Procedures

Magnesium Hydroxide System
Remote Auto Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump and mixer On/Off/Remote selector switches in the REMOTE position.
2. Through the PCS:
a) Enter the mixer frequency and duration timer set points
b) Enter a dosage set point for the chemical pump
c) Set the Magnesium Hydroxide Pump to AUTO mode
d) Initiate a START command for pump to operate

Remote Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump and mixer On/Off/Remote selector switches in the REMOTE position.
2. Through the PCS:
a) Enter a pump speed set point
b) Set the Magnesium Hydroxide Pump to MANUAL mode
c) Initiate a START command for pump to operate
d) Set the tank mixer to MANUAL mode
e) Initiate a START command for mixer to operate

Local Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, establish a pump speed set point through the Adjustable Frequency Drive.
2. Place the pump On/Off/Remote selector switch in the ON position.
3. Place the mixer On/Off/Remote selector switch in the ON position.

Alum System
Remote Auto Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump On/Off/Remote selector switch in the REMOTE position.
2. Through the PCS:
a) Enter a dosage set point
b) Set the Alum Pump to AUTO mode.
c) Initiate a START command for pump to operate.

Remote Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump On/Off/Remote selector switch in the REMOTE position.
2. Through the PCS:
a) Enter a pump speed set point
b) Set the Alum Pump to MANUAL mode.
c) Initiate a START command for pump to operate.

Local Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, establish a pump speed set point through the Adjustable Frequency Drive.
2. Place the On/Off/Remote selector switch in the ON position.

Polymer System
Remote Auto Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump and mixer On/Off/Remote selector switches in the REMOTE position.
2. Through the PCS:
a) Enter the mixer duration timer set point
b) Enter a dosage set point for the chemical pump
c) Set the Polymer Pump to AUTO mode
d) Initiate a START command for pump to operate

Remote Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, place the pump and mixer On/Off/Remote selector switches in the REMOTE position.
2. Through the PCS:
a) Enter a pump speed set point
b) Set the polymer Pump to MANUAL mode
c) Initiate a START command for pump to operate
d) Set the tank mixer to MANUAL mode
e) Initiate a START command for mixer to operate

Local Manual Control Mode:
1. On LP2100, located in the enclosure south of the Blower Building, establish a pump speed set point through the Adjustable Frequency Drive.
2. Place the pump On/Off/Remote selector switch in the ON position
3. Place the mixer On/Off/Remote selector switch in the ON position.

Polymer Batching
Local:
Polymer batches are typically made up on a daily basis. Depending on how much polymer is remaining in the tank from the previous day, the operator will have to calculate the day’s fill volume (total fill volume – remaining volume) and calculate how much dry polymer is needed for that volume to establish the desired polymer dosage.
1. Measure out the recommended amount of dry polymer to make up the day’s tank volume.
2. At the pushbutton station, located next to the Polymer Tank:
a) Push the Reset button
b) Place the water fill valve Open/Close switch into the Open position.
3. Manually open the eductor water valve and educt the dry polymer up into the open hose end.
4. When all dry polymer has been transferred, manually close the eductor water valve.
5. At the mixer pushbutton station, push the mixer Start button. The polymer mixer will run for the time duration established through the PCS and automatically shut off.
6. The water fill valve will automatically close when the Fill set point is reached. Alternatively, the operator can place water fill valve Open/Close switch into the Close position.

Shutdown Procedures

Chemical Systems (Typical)
Remote-Auto Mode:
1. Through the PCS, initiate a STOP command for pump to shut down.

Remote Manual Mode:
1. Through the PCS, initiate a STOP command for pump to shut down.

Local Manual Mode:
On LP2100, located in the enclosure south of the Blower Building, place the On/Off/Remote selector switch in the OFF position.


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Last Updated: 9/16/2013 9:24:59 AM
Version 4.0.1