In 2019, ISO released ISO 22519:2019 "Pretreatment and Production Systems for Purified Water and Injection Water", which specifies the design, material selection, construction, and operational requirements for pretreatment and production systems for purified water and injection water. The interpretation is as follows:

 ·The system boundary of the purified water/injection water pretreatment and production system starts from the valve (including valve) before the first water supply filter component/multimedia filter, and ends at the inlet valve (including) of the PW/WFI storage tank. If a storage tank is not installed, it is located at the end of use.

 ·When installing PW/WFI pre-treatment and production systems, the concept of "clean construction" should be adopted: providing pipelines and equipment under clean conditions, as well as installation methods to prevent pollutants from entering.

 ·The document provides recommended water quality standards for different stages of the water production system (RO inlet, RO outlet, purified water, injection):

 ·During the production process, the PW/WFI pretreatment and production system should control the highest water temperature in the system. During the production process, the maximum temperature in the system should not exceed 25 ℃ (guide value).

 ·Regarding hot water disinfection, it is required that during the disinfection period, all points of the system should be ≥ 80 ℃ (guidance value).

 ·The scope of the User Requirements Specification (URS) for water production systems provided in the document should include the following aspects:

Select water standards based on the supplied products;

Specification of final water standard parameters;

Requirements for system safety and good production practices;

List of main components;

Preliminary estimation of production flow rate;

The number of production units;

Functional requirements

Material requirements

Surface polishing of equipment

Biological control requirements

Advanced control: interlocks, alarms, and alarms;

Required documents (see Article 14);

Verify according to the requirements of relevant institutions;

Performance Qualification (PQ) monitoring parameters.

 ·URS should also be based on analysis of raw water from different seasons throughout the year, including chemistry and microbiology, to develop appropriate requirements.

 ·The file provides the advantages and disadvantages of different system components, such as:

 ·Pre treatment, ultrafiltration, and microfiltration membrane processes can be used to remove suspended solids, bacteria, and TOC upstream of RO.

 ·Multi media filter: Remove coarse particles within the range of 30 micron-50 microns before RO, and discharge them by flushing with return water.

 ·Flushing filter/disc filter (FS/DF): Remove coarse particles within the range of 30 microns to 50 microns upstream of RO.

 ·Chlorination: Input or produce chlorine and/or chlorine to maintain residual chlorine levels in the system within the range of 0.2 ppm -0.5 ppm (with appropriate contact time), in order to control the system itself and the levels of introduced bacteria.

 ·Chlorine dioxide (CD): Produce and inject chlorine dioxide to reach 0.1ppm -0.4ppm (with appropriate contact time) to control the system itself and the level of introduced bacteria.

 ·Softener: used to replace magnesium calcium, titanium, and plutonium with sodium to reduce scaling and precipitation on the RO membrane. A 10 micron to 20 micron resin drain valve is recommended downstream of the RO membrane.

 ·Anti scaling agent (AS): Add chemicals to the RO inlet to reduce hard precipitates on the RO membrane.

 ·Electronic descaling device (ESC), activated carbon filter (ACF)/granular activated carbon (GAC), sodium thiophosphate (SBS), chloramine, sodium hydroxide (NaOH), UV lamp, single pass reverse osmosis, double pass reverse osmosis, etc

 ·Regarding material requirements, stainless steel (SS) 316/316L should be used, including pipes/pipelines, storage tanks, pumps, heat exchangers, valves, instruments, and other accessories.

 ·Other materials that can be used:

EPDM

Polytetrafluoroethylene (PTFE)

Fluoroelastomer (FKM PEEK)

PFA plastic

L High grade (low impurity) fused silica

Other non corrosive, hot water resistant (HW5), non particle shedding, and non degreasing materials.

 ·Should consider being exposed to hot water disinfection at temperatures between 80 ° C and 90 ° C

 ·Request for physical air blocking: The distance from the bottom of the pipeline to the highest point of the drainage outlet should be at least 50 mm.

 ·Regarding the gasket, it should be one of the following:

Use PTFE gaskets covered with EPDM;

Overall EPDM (ethylene propylene diene monomer rubber)

Overall PTFE (polytetrafluoroethylene)

Silicone

Fluorinated elastomers

A combination of inert, hot water resistant (HWS), non particle shedding, and non degreasing elastomers.

 ·Regarding dead corners, a new 3D concept is proposed using L/D measurement, where L is the length of the dead corner perpendicular to the flow direction from the inner wall of the pipeline, and D is the inner diameter of the dead corner or the nominal size of the valve or instrument; L/D should be 3:1 or less.

 ·Regarding pipelines, different requirements have been put forward for PW/WFI contact pipelines and non PW/WFI contact pipelines:

 ·For non PW/WFI contact pipelines, manual butt welding is allowed without the need for endoscopic inspection and passivation; The pipeline standard is 3A/food grade, and flange connections are allowed; Do not allow threaded connections

 ·For PW/WFI contact pipelines, stricter requirements are proposed:

 ·The minimum acceptable ID polishing is Ra ≤ 0.6 microns;

 ·Welding should be carried out by rail welding machines as much as possible, with 70% of automatic welds inspected and 100% of manual welds inspected by endoscopy;

 ·Welding should use TIG/GTAW 99.997% argon gas protection;

 ·Starting work every day and conducting testing and sampling on each section of the pipeline;

 ·Welding records should be established, including:

 ·Welding date

Welding date

Welder's name

Supervisor/Inspector

Weld identification number and description

Description of welding items

Item diameter

The furnace number of the welded item

 ·Passivation should be carried out

 ·Only certified welders can be used

 ·Clamp (TC) or other sanitary means should be used for connection.

 ·Do not use threaded or flange connections.

 ·A minimum drainage slope of 1% should be designed

 ·The installed valve should be one of the following types: diaphragm valve or other sterile design, with a barrier between the valve mechanism side and the PW/WFI side.

 ·In the entire system, both non PW/WFI and PW/WFI pipelines should use zero dead angle sampling valves.

 ·There should be a sampling valve before and after each process related component in the water system, such as a heat exchanger, filter, pump, etc

 ·Minimum sampling point and position

1. Before and after the multimedia filter

2. Water supply pipe inlet

3. After the circulation pump

4. After the hardness reduction stage;

5. Filter inlet and outlet;

6. After the heat exchanger

7. After dechlorination;

8. After each RO and at its confluence;

9. RO exhaust outlet

10. CDI/EDI/CEDI inlet, outlet, and drainage.

·Regarding conductivity, if an online conductivity instrument is installed and the online conductivity meets national regulations, there is no need to take offline samples for conductivity testing.