One-way valve (bow tie with an arrow)
The standard’s wording, as the sources below reproduce it:
“Indicates a medical device with a valve that allows flow in only one direction.”
ISO 15223-1:2021, 5.6.6
What it means for you
Fluid can pass the valve only in the direction of the arrow, so it cannot run back — for example blood backing up an infusion line. Connect it the way the arrow points.
Whether a device is right for you is a question for your pharmacist, nurse or doctor.
- What it looks like
- Two triangles meeting at their points like a bow tie (the valve), with an arrow underneath pointing the way the flow may go.
- Where you see it
- Infusion sets and extension lines, needle-free connectors, drainage bags and some catheters.
- Other names
- check valve; non-return valve; bow tie arrow
What it does not tell you
It does not give the opening pressure or say the valve is sterile; the instructions for use give those details.
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 5.6.6 “One-way valve — Indicates a medical device with a valve that allows flow in only one direction.” Checked 2026-09-28.
- STERIS: STERIS Product Labeling, SCS-145, Exhibit A: Symbol Glossary — Shows the bow tie over an arrow for I.S. EN ISO 15223-1:2021 5.6.6 with the same explanatory text. Checked 2026-09-28.
Plain-language parts are in our own words; quotations are the sources’ wording.