Capillary tube symbol
Also called Filled system
A capillary tube is a sealed, fluid-filled tube connecting a sensor to an instrument, used in filled thermal and pressure systems.
What the capillary tube symbol means
A capillary tube is a sealed, fluid-filled tube connecting a sensor to an instrument, used in filled thermal and pressure systems.
How it is drawn
A thin line with small crosses at intervals.
The capillary tube symbol in each standard
Drawn as ISA 5.1 defines it, as on most US and international legends.
Signal lines are not part of ISO 10628-2. They come from IEC 62424 or ISA 5.1.
German (DIN): Kapillarleitung. See DIN P&ID symbols.
Where you see it on a P&ID
On filled thermometers, remote seals and some level instruments.
Tag codes
The capillary tube is commonly tagged:
- ISA 5.1
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 capillary tube symbol look like on a P&ID?
A thin line with small crosses at intervals.
What is a capillary tube used for?
A capillary tube is a sealed, fluid-filled tube connecting a sensor to an instrument, used in filled thermal and pressure systems. You will find it on filled thermometers, remote seals and some level instruments.
What tag does a capillary tube have?
It is commonly tagged ISA 5.1. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the capillary tube symbol the same in ISA and ISO?
Signal lines are not part of ISO 10628-2. They come from IEC 62424 or ISA 5.1. Companies vary the details, so always check the legend sheets at the front of the P&ID set.
What is the capillary tube called in German?
Kapillarleitung. 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