Filter symbol
A filter removes particles from a liquid or gas with a filter element. A differential pressure reading across it shows when it needs changing.
What the filter symbol means
A filter removes particles from a liquid or gas with a filter element. A differential pressure reading across it shows when it needs changing.
How it is drawn
A square turned on its corner (a diamond) with a dashed line across the middle for the filter element.
The filter symbol in each standard
Drawn as on most US-style legend sheets.
Liquid filter (general). A box with a dashed line for the filter element. Gas filters (X8122) and cartridge, bag and bed filters have their own numbers.
ISO SVG
German (DIN): Filter. See DIN P&ID symbols.
Where you see it on a P&ID
On fuel gas, lube oil, instrument air, water injection and upstream of sensitive equipment.
Tag codes
The filter is commonly tagged:
- F
- FL
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 filter symbol look like on a P&ID?
A square turned on its corner (a diamond) with a dashed line across the middle for the filter element.
What is a filter used for?
A filter removes particles from a liquid or gas with a filter element. A differential pressure reading across it shows when it needs changing. You will find it on fuel gas, lube oil, instrument air, water injection and upstream of sensitive equipment.
What tag does a filter have?
It is commonly tagged F, FL. The exact tag format comes from the project numbering procedure and the legend sheets.
Is the filter symbol the same in ISA and ISO?
No. A box with a dashed line for the filter element. Gas filters (X8122) and cartridge, bag and bed filters have their own numbers. The ISO 10628-2 registration number is X8116. Always check the legend sheets at the front of the P&ID set.
What is the filter called in German?
Filter. 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