We design and sell a complete line of DI and RO/DI hybrid water processors. So we naturally get a lot of request for information about DI material compatibility. The table below lists the most common interactions. Bear in mind that anything metallic will yield a small amount of metal back into the water until passivated, and then still smaller amounts after that. Depending on how critical you application is, be sure to perform appropriate bench-testing. Talk to your local Clean Water Crusader if you require more detailed information or design assistance.
Common Industrial Materials and their compatibility with deionized water
|304 stainless steel||A1-Excellent|
|316 stainless steel||A2-Excellent|
|Buna N (Nitrile)||A1-Excellent|
|Carbon Steel||D-Severe Effect|
|Cast iron/Galvanized Iron/Ductile/Black Iron Pipe||D-Severe Effect|
|ChemRaz (FFKM)||D-Severe Effect|
|Polyetherether Ketone (PEEK)||N/A|
Ratings – Chemical Effect
A = Excellent
B = Good
Minor Effect, slight corrosion or discoloration
C = Fair
Moderate Effect, not recommended for continuous use. Softening, loss of strength, swelling may occur
D = Severe Effect, not recommended for ANY use.
N/A = Information Not Available.
Explanation of Superscript
1. Satisfactory to 72°F (22° C)
2. Satisfactory to 120°F (48° C)
Some of the questions received about this page:
Q: An Auditor questioned our use of a rubber hose and Tygon tubing for transfer of DI water in our BOD testing. Was wondering if these are acceptable?
A: Certain rubbers can add to the BOD and/or COD of the water, especially at elevated temperatures.
More importantly, when BOD is critical and the process requires in-situ disinfection, rubber interacts negatively with most disinfectants and creates a home for biofilm; so I generally advise against rubber tubing where BOD is important.
Tygon generally doesn’t impact BOD (unless bacterially contaminated) and works better with a broader range of disinfectants.
When selecting tubing, also make sure that the tubing is certified for the application at the temperature.
Q: Do you have any data with RO water compatibility with stainless steels at 180 F?
A: At higher temperatures, the effects of water chemistry and dissolved gases are significantly more pronounced.
As long as your purified water chloride level is <5ppm and your dissolved CO2 and O2 are low, one would not expect to see any corrosion or premature failure with stainless steel.
Q: Is cast iron pipe compatible with DI water?
A: Absolutely not, under no circumstances. Don’t even think about it!
Q: What material is compatible with reverse osmosis water?
A: Think of Reverse Osmosis (R/O) water like deionized water, but with more dissolved gasses. It can sometimes be more or less corrosive than DI water, depending on site-specific chemistry. Test the water and apply appropriate caution.