Fluid path (square bracket)
The standard’s wording, as the sources below reproduce it:
“Indicates the presence of a fluid path.”
ISO 15223-1:2021, 5.6.2 · ISO 7000-2722
What it means for you
Marks the part of the device that fluid runs through. It is a building block: combined with STERILE it becomes the sterile-fluid-path mark, combined with the wavy lines it says the fluid path is non-pyrogenic.
Whether a device is right for you is a question for your pharmacist, nurse or doctor.
- What it looks like
- A double-lined bracket like a square letter C turned to open left. Usually combined with another mark inside or next to it, such as STERILE or the non-pyrogenic wavy lines.
- Where you see it
- Infusion sets, blood lines, syringe pump sets and extension tubing.
- Other names
- fluid pathway; double bracket
What it does not tell you
On its own it promises nothing about sterility or pyrogens; the mark it is combined with does.
Often confused with
Indicates the presence of a sterile fluid path within the medical device in cases when other parts of the medical device, including the exterior, might not be supplied sterile.
More symbols in “Tubes, lines and valves”
Sources
ISO 15223-1 is a paid standard, so the wording above is quoted as 2 publishers’ public documents reproduce it. Each was fetched and read on the date shown:
- Boston Scientific: Symbols Glossary — ISO 15223-1 5.6.2 “Fluid path — Indicates the presence of a fluid path.” Checked 2026-09-28.
- NE Scientific: Master Symbol Glossary (CTF-100011 Rev 01) — Shows the double bracket for reference no. 5.6.2 (ISO 7000-2722): “Indicates the presence of a fluid path.” Checked 2026-09-28.
Plain-language parts are in our own words; quotations are the sources’ wording.