Three-way valve symbol
Also called Diverting valve, Mixing valve
A three-way valve has three ports. It either diverts one flow to two outlets or mixes two flows into one.
What the three-way valve symbol means
A three-way valve has three ports. It either diverts one flow to two outlets or mixes two flows into one.
How it is drawn
Three triangles meeting at their points in the middle, one on each port.
The three-way valve symbol in each standard
Drawn as on most US-style legend sheets.
Valve, three way type (general). Drawn the same way: a third triangle on the branch.
German (DIN): Dreiwegeventil. See DIN P&ID symbols.
Where you see it on a P&ID
On temperature control (mixing or bypassing an exchanger), diverting to two destinations, and switching between duty and standby equipment.
Tag codes
The three-way valve is commonly tagged:
- HV
- TV or FV when actuated
Tag formats follow the project numbering procedure. For instruments, the letters follow ISA 5.1, explained on the instrument symbols page.
Related symbols
Frequently asked questions
What does the three-way valve symbol look like on a P&ID?
Three triangles meeting at their points in the middle, one on each port.
What is a three-way valve used for?
A three-way valve has three ports. It either diverts one flow to two outlets or mixes two flows into one. You will find it on temperature control (mixing or bypassing an exchanger), diverting to two destinations, and switching between duty and standby equipment.
What tag does a three-way valve have?
It is commonly tagged HV, TV or FV when actuated. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the three-way valve symbol the same in ISA and ISO?
Yes, ISO 10628-2 draws it the same way (2103). Companies vary the details, so always check the legend sheets at the front of the P&ID set.
What is the three-way valve called in German?
Dreiwegeventil. On a German R&I-Fließschema it is drawn to DIN EN ISO 10628-2.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016