Integrated Dosing System Troubleshooting: Mixing, Level and Pump Control
An integrated dosing system combines dissolving, maturing, storage and injection in one skid. Water inlet, chemical feed, mixing, level control and metering pump dosing are all handled automatically by the controller, which saves a great deal of manual work. The downside is that there are many stages, and a problem in any of them stops the chemical. Troubleshooting an integrated dosing system starts with finding which stage is at fault and then working through that stage.
What an Integrated Dosing System Contains
A typical integrated dosing system includes a dissolving tank and a maturing tank with mixers, a storage tank, a powder feeder or liquid chemical feed, an inlet solenoid valve and flow meter, level switches or transmitters, metering pumps and a control panel.
The sequence goes like this. When the storage tank level is low, the controller opens the water valve and starts the feeder. The mixer dissolves the chemical, the solution matures for a set time and transfers to storage, and the metering pump draws from storage and doses. Knowing this sequence tells you what to check at each step.
Dissolving and Mixing
Undissolved chemical, lumps or fish eyes
This is the most common of all PAM dosing unit faults. Polyacrylamide powder clumps in water and forms fish eyes, wet outside and dry inside. Causes include a feed rate that does not match the water flow, a damp and caked feed inlet, powder entering the water before it disperses, insufficient mixer speed or time, and too short a maturing time.
Clean the feed inlet and screw and keep them dry. Check the ratio of powder to water. Verify mixer speed and run time. Set maturing time according to the chemical supplier's guidance.
Mixer not turning or noisy
Check motor power, the overload relay, gearbox oil and whether the shaft or impeller is loose or wrapped with material. A stopped mixer leaves the solution layered and poorly dissolved.
Level Control
Overflow or empty tanks
Level switches coated with crystals or sticky solution give false signals. Water may keep running until the tank overflows, or never start so storage runs dry. Viscous PAM solution is especially good at coating floats and electrodes.
Clean the switches regularly and check wiring and signals. For viscous solutions, consider level detection that resists fouling.
Uncontrolled water inlet
A stuck solenoid valve, a failed coil, low water pressure or a blocked strainer all upset the water volume. Check valve operation, supply pressure and the strainer.
Chemical Feed
A jammed feeder screw, a failed motor or bridging in the hopper interrupts powder feed and weakens the solution. A failed liquid feed pump does the same for liquid chemicals. Check the feeder, clean the hopper and keep powder dry.
Metering Pump Interlocks
Pump will not start
Metering pumps in an integrated dosing system are interlocked with the controller. They stop on low storage level and start on a run command or external signal. If a pump will not start, check whether the controller has issued a run command, whether the storage level has tripped the stop, and whether the pump is in remote mode.
Wrong dose
Pump problems such as air in the head, sticking valves or low back pressure are handled with normal metering pump checks. PAM solution is viscous and resists suction, so confirm the suction line is large enough, the lift is low and the pump type suits viscous liquids.
Controller
When the touch screen or controller alarms, read the message and the alarm history. Common alarms are level faults, motor overload, feed faults and water faults. Sensor signal faults, loose wiring and accidentally changed parameters also stop the automatic sequence.
Record the original settings before changing parameters so they can be restored. Program faults need the equipment supplier.
Troubleshooting Order
Follow the flow of the chemical. Check water inlet and feed first, then dissolving and maturing, then level control and transfer, and finally metering pump dosing. Once each stage is confirmed, the faulty one stands out.
Routine Maintenance
On daily rounds, look at how well the solution is dissolved, the tank levels and the metering pumps. Clean the dissolving, maturing and storage tanks regularly to remove deposits and lumps. Clean level switches and the feed inlet. Check mixer and gearbox lubrication. Clean metering pump valves and replace wear parts on schedule. Store powder in a dry place. An integrated dosing system that gets this attention runs for long periods without intervention, and when an integrated dosing system does alarm, the cause is usually found within minutes.
Questions to Ask When Buying an Integrated Dosing System
Many faults can be avoided at the purchasing stage. Ask the supplier how the integrated dosing system handles viscous PAM solution, which level detection it uses in each tank, and whether the metering pumps are rated for the solution viscosity. Ask how alarms are displayed and whether they can be sent to the central control room. Ask for a clear operating manual with parameter lists. An integrated dosing system bought with these answers in hand is much easier to keep running, and operators can troubleshoot the integrated dosing system without waiting for a service visit.
FAQ
PAM is not dissolving and has fish eyes. What should I do?
Check whether the feed inlet is damp, the powder to water ratio, mixer speed and maturing time, and adjust to the chemical supplier's guidance.
Why does the storage tank overflow?
Usually a fouled level switch or a stuck inlet valve. Clean the switch and check the valve.
The metering pump in the unit will not start. Why?
Check the controller's run command and the storage level interlock first, then whether the pump is in remote mode.
How long should maturing time be?
Follow the chemical supplier. Different products need different times.
How often should the unit be cleaned?
It depends on the chemical and use. Clean as soon as deposits or lumps appear.
Conclusion
Integrated dosing system faults can be traced stage by stage: dissolving and mixing, level control, chemical feed, metering pump interlocks and the controller. PAM dosing unit faults mostly involve poor dissolving, fouled level switches and difficult dosing of viscous solution. Follow the chemical flow, keep up routine cleaning and rounds, and most problems can be prevented or fixed quickly. For replacement metering pumps or parts, contact us.