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Major Factors to Consider in Designing and Installing a Chemical Injection Skid System

4. Control Systems For The Skid

scada monitoring - AquFlow Metering Pumps

This is where we decide about the controls for the delivery of the chemical (and hence the pump) and sensors to verify if the system is doing what it is expected to do.

The first thing we take into consideration here is the power that is available. That will determine the selection of the motor, sensor and controls. Usually that power is single or three phase AC voltage. Although in remote areas there could be the need for DC power especially if the source is a generator or solar.

The flow of the chemical can be regulated by using a VFD on the motor to regulate the speed or by an automatic stroke adjustment system (like AquFlow’s ECCA) which will increase or decrease the effective stroke length. Many engineers prefer a combination of the two controls calling it a Dual Axis control. Both these controls can be driven by a 4-20 mA signal from an external system such as SCADA which takes into consideration several other inputs such as flow or quantity of the water to be treated, contamination level etc.

Once the flow of the chemical is controlled it is often recommended to measure the output of the chemical in the pipe line by suing a flow measurement device. This device again communicates back to a central system like SCADA which takes this input and fine tunes the pump flow capacity by one or both of the above methods.

If an external control system like SCADA is not available, AquFlow offers a self contained control unit called IVAX which stands for Intelligent Verification and Control System. This has the ability to offer a complete feedback loop to send control signal, verify the actual output with a flow sensor and make further adjustments to the flow capacity. Please click here for the link to the IVAX system
In addition AquFlow also offers standard control systems for common water treatment application such as,
AcidBot: Used for adjusting the water pH to the desired level by controlling the injection of acid or alkaline solution into the water.
ChemBot: Used where the chemical flow needs to self-adjust with the increase and decrease of the water flow. This system first monitors the water flow in the pipe and then regulates the chemical pump flow to keep the desired mix ratio.

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