RBergmann
Member
When using a dosing pump for polymer injection on a water project, the controller (i.e Hach SC100) sends a 4-20mA signal to control the stroke rate of the dosing pump base on water turbidity. This is a linear control, no special programming necessary except for setting the range (in NTU) for the 4-20mA signal. There is no requirement for a PLC or other device to assist in the stroke control. Straight forward linear control.
However, I am now tasked with controlling a dosing pump for chlorine feed based on a residual chlorine PPM. As I see it, the pump rate should be inversely proportional to the controller (Hach CL-17) output.
I am interested on the methods used by others for this type of control. There is an SLC 5/05 PLC in the system and I am passing the analog input signal (from the CL-17) through the PLC directly with separate AO channels for the dosing pump and a chart recorder.
... rab
However, I am now tasked with controlling a dosing pump for chlorine feed based on a residual chlorine PPM. As I see it, the pump rate should be inversely proportional to the controller (Hach CL-17) output.
I am interested on the methods used by others for this type of control. There is an SLC 5/05 PLC in the system and I am passing the analog input signal (from the CL-17) through the PLC directly with separate AO channels for the dosing pump and a chart recorder.
... rab