Pharmacopoeia Standard Water for Injection Equipment

Pharmacopoeia-standard Water for Injection (WFI) equipment must meet various requirements, as detailed below:

1. Core Production Equipment:
- Multi-effect Distillation Unit: This is the key equipment for producing Water for Injection. It uses purified water as feed water and, through multi-effect evaporation and condensation processes, removes impurities and non-condensable gases to obtain high-purity Water for Injection. The "multi-effect" design of the distillation unit enables energy savings by rationally utilizing thermal energy multiple times. For example, in a common triple-effect distillation unit, the first-effect evaporator uses external steam to heat the feed water and generate steam, which then serves as the heat source for the second-effect evaporator. The steam generated by the second effect is used for the third effect, and so on.
- Pure Steam Generator (optional): Used to produce pure steam for sterilizing and disinfecting Water for Injection equipment and pipeline systems, ensuring the system remains sterile. The pure steam generator uses deionized water or distilled water as feed water and removes any residual impurities during steam production to guarantee steam purity.
2. Pretreatment System:
- Raw Water Tank: Used to store raw water. Its material must comply with relevant hygiene standards to prevent contamination of the raw water. The raw water should meet drinking water standards; if not, pre-purification treatment is required.
- Raw Water Pump: Provides the driving force for raw water transportation, ensuring it flows smoothly into subsequent treatment stages.
- Filters: Include sand filters and activated carbon filters. Sand filters remove larger particulate impurities such as suspended solids and sediment from the raw water. Activated carbon filters adsorb organic matter, residual chlorine, etc., improving the odor and taste of the raw water and providing a better water quality foundation for subsequent deep treatments like reverse osmosis.
3. Reverse Osmosis Unit (optional): In some Water for Injection equipment systems, a reverse osmosis unit is included as part of the pretreatment. Using the principle of semi-permeable membranes, it allows water to pass through under pressure while retaining impurities, removing most salts, organic matter, microorganisms, etc., from the water. This further enhances water purity and provides higher-quality feed water for subsequent treatments like distillation.
4. Storage and Distribution System:
- Water for Injection Storage Tank: Made of 316L stainless steel, with electropolished and passivated inner walls. The tank must be sealed with a smooth inner surface to facilitate thermal and chemical disinfection and prevent biofilm formation. It should be equipped with a 0.2μm hydrophobic vent filter (breather) and be capable of withstanding disinfection with at least 121°C high-temperature steam, either through heat disinfection or a jacket. Drain valves should be made of stainless steel diaphragm valves.
- Water Supply Pump: Made of 316L stainless steel (wetted parts), electropolished and passivated, connected via sanitary clamps, and lubricated with purified water or Water for Injection itself to completely eliminate water accumulation. The water supply pump primarily provides the driving force for points of use, meeting the flow rate and pressure requirements of the workshop. It also employs variable frequency constant flow control to maintain a return flow velocity greater than 1 m/s, keeping the water system in a turbulent state to help prevent microbial growth.
- Piping: Made of 316L stainless steel pipes with electropolished and passivated inner walls. Pipes are welded using hot fusion TIG welding or connected in sections with sanitary clamps. Valves are made of stainless steel PTFE diaphragm valves with sanitary clamp connections. Piping must have a certain slope to facilitate drainage and be arranged in a looped configuration, with return water flowing back into the storage tank. Parallel or series connection methods can be used, with series connection being preferable.
5. Water Quality Monitoring and Control System:
- Water Quality Monitoring Instruments: Equipped with conductivity meters, Total Organic Carbon (TOC) analyzers, temperature sensors, pressure sensors, etc. Conductivity meters monitor ion content in real-time; the conductivity of Water for Injection must comply with pharmacopoeia standards (typically requiring low values). TOC analyzers detect the total amount of organic carbon in the water. Temperature and pressure sensors monitor temperature and pressure parameters during equipment operation.
- Control System: Uses PLC or other automated control systems to monitor and control the operation of the entire Water for Injection equipment, including starting and stopping various equipment, adjusting operating parameters, and recording and analyzing water quality monitoring data. If water quality parameters exceed set ranges, the system automatically alarms and takes appropriate measures, such as automatically switching to drainage or stopping equipment operation.
6. Disinfection and Sterilization Equipment:
- UV Sterilizer: Uses ultraviolet radiation to destroy the DNA structure of microorganisms, killing residual bacteria and viruses in the water. It is typically installed at key locations such as the inlet and outlet of pipes or storage tanks.
- Superheated Water Disinfection Unit: Used for periodic superheated water disinfection of pipes, storage tanks, and equipment. The disinfection temperature is generally 121°C to ensure the system remains sterile.

In summary, pharmacopoeia-standard Water for Injection equipment requires strict design and configuration across multiple stages, including production, pretreatment, storage and distribution, water quality monitoring, and disinfection/sterilization, to ensure the produced Water for Injection meets the quality standards specified by the pharmacopoeia.