Controls and Programming for A Multi-Level Filtration and
UV Treatment System

• • System Overview - Design a system that removes impurities, contaminants, and microorganisms from incoming city water. Achieve laboratory-quality water purity standards. Ensure reliable operation, ease of maintenance, and cost-effectiveness.
• • Control Systems - System uses an Allen Bradely PLC (Programmable Logic Controller) and HMI (Human-Machine Interface). PLC to HMI communication uses serial type as the distance is less than 10 feet. Digital I/O and circuits are PNP type. Analog I/O signaling is 4-20ma and 0-10vdc type. External PLC communication cabling is CAT 5 standard.
• • Programming - Programming will be completed in Allen Bradey (Rockwell) ladder logic. System will detect low level in purification water tank, and call for top up. City water valve will open and allow water to enter the system. Pump will handle delivering pressure to the system. Water will travel through the system and be delivered in purified form to the purified water holding tank. From there, based on demand will be distributed to the different laboratories throughout the facility. System will track via flow meters, the amount of water that has travelled through the system. The maintenance schedule will be determined by the client, and programmed into the PLC. Then at the set intervals will display reminders, warnings and alarms to check / change lights, pumps, filters, valves, etc. HMI will also include enable / disable system, service mode and test mode. HMI will also include warnings and faults with regard to water conductivity and PH. HMI will also include maintenance screen for various parameters to be adjusted based on client requirements or system customization.
• • Sensors and Transducers - Utilized flow meter for incoming city water and for water entering the purified tank. Conductivity and PH meters used to ensure quality of water. Pressure transducers used at critical points in the system to measure for pressure across key points. All sensor data is read via analog to the PLC and thresholds set to the data react appropriately.
• • HMI and User Interface - HMI separated into 3 main sections. Control / monitoring, engineering / administration, and warning / alarms. Control / monitoring displays current operation conditions and any warnings that might exist. Engineering / administration will handle any thresholds and parameters needed to set alarms and or faults. This section will also handle maintenance control of the system. This section will be behind a password. Warning / alarms will be displayed when a critical fault has occurred. A password will be needed to clear a critical fault.
• • System Integration - The system uses a variety of signaling throughout the system. Incoming flow meters are analog and will read their flow rates to the PLC. The level sensors are digital and their parameters set at the sensor itself. PH and conductivity meters are analog and read back to the PLC. Valves are controlled digitally and are piloted. The main water pump is controlled digitally through a standard contactor circuit. There is an audible alarm and Andon light at the main control panel that give visual and audible cues as to the system status. The HMI on the main control panel will report out on the status of the system. The user can then interact with the HMI.
• • Testing and Validation - The client determined their requirements for validation, (there is a 3rd party certification requirement). We then generated the process and documentation for completing the validation. Validation was completed with a cross-function team for system acceptance as per their GMP (Good Manufacturing Practices) system.
• • Conclusion - The multi-level filtration and UV treatment system designed and implemented, produced pure laboratory-quality water from incoming city water. The system's modular design, filter selection, and UV light treatment ensured effective contaminant removal and sterility. This project demonstrates the ability to design and implement a complex filtration system that meets specific purity standards.