COVNA Actuator In The Water Treatment System

What Is Water Treatment System

A water treatment system constitutes the preliminary, primary, secondary and tertiary treatment stages through which water/waste water is converted into potable water.In the preliminary stage with the aid of bar screen/grit removal system very large particles such as plastic,paper etc are removed. In the primary stage, the Total suspended solids are removed with the aid of clarifiers.The Biological Oxygen Demand and Chemical Oxygen demand are removed in the secondary stage with the aid of aeration process. The tertiary system constitutes filters to remove the remaining total suspended solids which is left. Also it constitutes f Reverse Osmosis system to removed Total Dissolved solids and other ions. In the treated water tank,chlorination is done in order to disinfect and remove the bacteria present in the water.

Role of Actuator in Water Treatment

A water treatment system constitutes various number of unit operations such as clarifier, filters, reverse osmosis systems etc. The flow, pH and pressure are the indicators if these unit operations are functioning properly or not. When these parameters deviate from the standard values, then the signals from the flow meter/pH meter/ pressure transmitter is sent to the SCADA/Direct control system which sends out electric signals/air supply to the actuators of these automatic valves to open/close them in order to rectify the problem.

Membrane cleaning, cleaning of filters are all done with the aid of automatic valves when the pressure exceeds the standard pressure. In order to avoid overflow or preventing drying of pumps due to insufficient flow of water, the signals indicated by the flow meters are picked up by the actuators which open/close the valves accordingly in order to have uninterrupted operations/services of the plant. In case the pH is too low/ high from the described limits this would affect the shell life of any unit operation. This fluctuation is detected by the pH meter and the signal to rectify is sent to the actuator of the control valve which is responsible for the addition of acid/alkali respectively.

In case of Anaerobic digestion, the sludge should be suspended in the system. To keep it suspended a particular flow of water should be maintained. In case this decreases/increases above the specified flow, then this detected by the flow meter which provides signal to the actuators of the control valve responsible for opening/closing of the water flow to the digestor. Thus the presence of auto-valves prevents the shut down of the plant.

Why CONVA Actuator?

The pneumatic actuator has an indicator that indicates the position of the valve whether the valve is open or not. In case it is closed when it has to be opened or the other way round, this is an indication there is an error in the system which needs to be analyzed and rectified. Thus this indicator allows us to identify the problem if any very quickly. Also the indicator has a mirror through which the position of the valve can be read and also this prevents the accumulation of water.

Secondly, the body of the actuators for both the pneumatic actuator and the electric actuator is made of aluminum. Aluminum doesn’t rust, unlike the iron and steel bodies. Also it forms aluminum oxide when exposed to air which forms a protective layer and prevents further reaction of the surface to the air. Thus aluminium made valves can be used to treat water/wastewater constituting high Total dissolved solids, metal ions, suspended solids etc. In such a case if valves made of iron or steel would be used than the wear and tear will be very high as it is prone to rust.

The pistons of both the pneumatic and the electric actuators are made of galvanized iron/steel or it is made of die-casting aluminum which are prone to rust. Thus this can be used to treat the water system where the total dissolved solids, suspended solids, pH is high. The preloaded spring of the pneumatic actuator is made of high quality which has a longer shelf life and which is corrosion resistant. Also by providing different spring quantity the changing torque requirements can be met easily which increases the efficiency of the valves at any situation. The NBR o rings of both the type actuators operate without any problem at different ranges of temperatures.

The motor of the electric type actuator is caged has a small inertia but a large torque. Also it has F type insulation which prevents overheating of the motor. Thus this prevents the wear and tear of the valve.