Safety Valves · Pilot-Operated Safety Valves
High-Efficiency Pilot Operated Safety Valves
The high-efficiency pilot operated safety valve (POSV) replaces the loaded spring of a conventional relief valve with a main valve and a pilot that senses line pressure: opening and closing are pilot-controlled, so the main valve achieves full lift with a short blowdown and holds set pressure up to 97% of the operating pressure — a much tighter margin than spring valves allow. The benchmark execution spans DN 25 to DN 200 (NPS 1 to 8), set pressures 1.0 to 650.0 barg (15.0 to 9427.0 psig) and -162 to 320°C (-260 to 608°F) across orifices D to T+, with back-pressure tolerated to 95% of set pressure.
Part of the Pilot-Operated Safety Valves family
Last updated: 2026-11
Specifications
| set pressure range | 1.0–650.0 barg (15.0–9427.0 psig) |
|---|---|
| pressure class | PN 10 - PN 400 | CL150 - CL2500 |
| size range | DN 25 to DN 200, NPS 1 to NPS 8 |
| capacity orifice | D to T+ |
| body materials | Carbon steel, Stainless steel |
| end connections | Flange acc. to DIN EN 1092 or acc. to ASME B 16.5 or acc. to JIS 2220 |
| temperature range | -162 to 320 °C (-260 to 608 °F) |
| design standards | API 526 |
| design | Pilot-operated safety valve (POSV) |
| operating pressure ratio | Up to 97% of set pressure |
| back pressure ratio | Up to 95% of set pressure |
| pilot action modes | Pop Action, Modulate Action |
Application & selection guidance
Size the orifice (D to T+) for required capacity, then select the body — carbon steel or stainless steel — against the process fluid and temperature. The 97% operating-to-set-pressure ratio suits systems running close to their relief set point, and the 95% back-pressure tolerance allows a common discharge header where spring-loaded valves would need individually sized tails.
Frequently asked questions
How does a pilot operated safety valve differ from a spring-loaded safety valve?
A pilot senses system pressure and controls the main valve instead of a large mechanical spring. The result is full-lift opening with a short blowdown, and set behaviour that stays accurate at operating pressures up to 97% of set pressure, where a spring valve would already be weeping.
What set-pressure range and back-pressure can the high-efficiency POSV handle?
Set pressures from 1.0 to 650.0 barg (15.0 to 9427.0 psig) over -162 to 320°C (-260 to 608°F), with back-pressure tolerated up to 95% of set pressure — enough to share a common discharge header in most installations.
What sizes and materials are available?
Inlet sizes DN 25 to DN 200 (NPS 1 to 8) with orifices D to T+, in carbon steel or stainless steel bodies selected against the process fluid and temperature within the -162 to 320°C window.
Ordering & documentation
Documents
Ask for the documentation set you need with the inquiry — typical items for this execution (material certificates, test reports to the listed inspection standard, dimensional drawings) are confirmed and supplied with the quotation.
Quotation
A quotation-ready inquiry states: nominal size and pressure rating, body and seat material preference, end connection, operation, and the service medium with temperature. Typical values on this page are benchmark reference ranges; the binding values are confirmed at quotation.
Sample & supply
Supply terms, order quantities and lead time are agreed per order — state the destination country and required schedule with the inquiry.
Storage & shipping
Store valves with seats and seals protected from UV, ozone and deformation, keep end-face protectors on until installation, and for elastomer- or PTFE-seated executions avoid prolonged outdoor storage — seat compounds age fastest in direct sunlight and freezing conditions.
Knowledge: selection guides
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