Pressure safety valve symbol
Also called PSV, Relief valve, PRV, Safety relief valve
A pressure safety valve opens automatically when pressure rises above its set pressure, releases fluid to a safe place and closes again when pressure falls. It is the last line of defence against overpressure.
What the pressure safety valve symbol means
A pressure safety valve opens automatically when pressure rises above its set pressure, releases fluid to a safe place and closes again when pressure falls. It is the last line of defence against overpressure.
How it is drawn
An angle valve body with the inlet from below, the outlet to the side, and a zig-zag spring above. The set pressure is written beside the tag.
Variants
- Pilot-operated relief valve
- Pressure-vacuum relief valve on tanks
The pressure safety valve symbol in each standard
Drawn as ISA 5.1 defines it, as on most US and international legends.
Safety valve, spring loaded, globe angle type. An angle globe valve (dot in the centre) with a spring on top and a heavy bar across the outlet side. The straight-through version is X2124.
ISO SVG
German (DIN): Sicherheitsventil. See DIN P&ID symbols.
Where you see it on a P&ID
On every vessel, exchanger, pump discharge or line that could be overpressured, discharging to flare, vent or a drain.
Tag codes
The pressure safety valve is commonly tagged:
- PSV
- PRV
- TSV (thermal relief)
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 pressure safety valve symbol look like on a P&ID?
An angle valve body with the inlet from below, the outlet to the side, and a zig-zag spring above. The set pressure is written beside the tag.
What is a pressure safety valve used for?
A pressure safety valve opens automatically when pressure rises above its set pressure, releases fluid to a safe place and closes again when pressure falls. It is the last line of defence against overpressure. You will find it on every vessel, exchanger, pump discharge or line that could be overpressured, discharging to flare, vent or a drain.
What tag does a pressure safety valve have?
It is commonly tagged PSV, PRV, TSV (thermal relief). The exact tag format comes from the project numbering procedure and the legend sheets.
Is the pressure safety valve symbol the same in ISA and ISO?
No. An angle globe valve (dot in the centre) with a spring on top and a heavy bar across the outlet side. The straight-through version is X2124. The ISO 10628-2 registration number is X2125. Always check the legend sheets at the front of the P&ID set.
What is the pressure safety valve called in German?
Sicherheitsventil. 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