What Is PN in Valves? Pressure Rating Explained
What Is PN in Valves?
PN stands for nominal pressure. In valve terminology, PN is used to indicate a pressure rating class for valves, flanges and pipeline components. It helps engineers and purchasers understand whether a valve is suitable for the pressure condition of a pipeline system.
PN is commonly used in metric-based valve and piping standards. Examples include PN 6, PN 10, PN 16 and PN 25. A higher PN rating generally indicates a higher pressure class, but final selection should always consider the applicable standard, temperature, material, fluid type and system condition.
Why PN Rating Matters
PN rating is one of the first technical points checked during valve selection. If the valve pressure rating is lower than the actual system pressure, the valve may not be suitable for the line. If the pressure rating is much higher than required, the valve may be heavier or more expensive than necessary.
Pressure rating should not be checked alone. Valve selection should also include flange compatibility, test standard, material compatibility, operating temperature, sealing arrangement and installation condition.
PN 6/10 Example
PN 6/10 means that the valve is associated with PN 6 and PN 10 pressure classes, depending on the product design, application and catalog specification.
For example, Knife Valve PN 6/10 is used for isolation service in viscous fluids, slurry, sludge, chemical sludge, sugar paste and waste stream applications. In this case, PN 6/10 should be checked together with flange standard, test standard, medium type and installation requirements.
PN vs Class
PN and Class are both used to describe pressure rating systems, but they belong to different standard systems.
PN is commonly used in metric and European-based standards.
Class ratings such as Class 150 or Class 300 are commonly used in ASME-based valve and piping systems.
They should not be treated as identical values. Conversion between PN and Class depends on the standard, material group and temperature condition.
What Should Be Checked Before Selecting a PN-Rated Valve?
Before selecting a valve based on PN rating, the following points should be reviewed:
System operating pressure
Operating temperature
Fluid type
Material compatibility
Flange standard
Test standard
Valve type
Sealing arrangement
Installation position
Maintenance access
Applicable project specification
A valve should not be selected only by PN rating. PN is important, but it is only one part of the technical selection process.
Related Product
Knife Valve PN 6/10 is an example of a PN-rated valve used for slurry, sludge, viscous fluids and industrial waste stream applications.
Related Application Page
For application-based valve selection, see Valves for Slurry and High-Viscosity Fluids.
Related Technical Article
For more information about knife valve design and applications, see What Is a Knife Valve? Applications, Design and Selection Notes.
FAQ
What does PN mean in valves?
PN means nominal pressure. It is used to indicate the pressure rating class of valves, flanges and pipeline components.
Is PN the same as working pressure?
No. PN is a nominal pressure rating. Actual allowable working pressure can depend on material, temperature, standard and service condition.
What does PN 6/10 mean?
PN 6/10 indicates that the valve is associated with PN 6 and PN 10 pressure classes according to the product specification.
Is PN the same as Class?
No. PN and Class are different pressure rating systems. PN is commonly used in metric and European-based standards, while Class ratings are commonly used in ASME-based systems.
Can a valve be selected only by PN rating?
No. PN rating should be checked together with fluid type, temperature, material compatibility, flange standard, test standard and installation condition.