DI, WFI and Sterile Water for LN₂ Foggers
Applied Physics public AP Series materials identify DI water, Water for Injection and sterile water as operating inputs. The selected grade should match the current manual and the facility’s contamination-control strategy.
Water grade is not the whole control
Two containers labeled “DI water” can differ in resistivity, microbial condition, endotoxin status, storage time and handling. WFI and sterile water have distinct specifications and controls, but transferring either into an unclean chamber can erase the advantage. The equipment cleaning state, fill container, transfer method and hold time belong in the protocol.
Minimum planning questions
- What exact water types are permitted by the current model manual?
- Who releases the water and how is its identity recorded?
- How long may water remain in the chamber before draining?
- What rinse, cleaning and drying procedure applies between studies?
- Is the receiving process sensitive to moisture or condensation?
- Will the study require a sample, lot record or certificate?
Do not improvise chemistry
The strongest SOP ties the water lot, equipment ID, pre-use inspection and post-use drain/dry record to the study package.
Build a defensible fogger requirement
Send Applied Physics the room, process, utilities, documentation and safety constraints—not just a model number.