PN16 to PSI and PN25 to PSI: Valve Pressure Conversion Guide

PN16 converts nominally to 232.1 psi, while PN25 converts nominally to 362.6 psi. For quick field calculations, these values are normally rounded to 232 psi and 363 psi.

The conversion formula is straightforward:

Pressure in psi = pressure in bar × 14.5038

Therefore:

• PN16: 16 bar × 14.5038 = 232.1 psi
• PN25: 25 bar × 14.5038 = 362.6 psi

These figures are useful when comparing metric valve specifications with project documents written in psi. However, the converted number is only a nominal pressure reference. It does not prove that every PN16 valve can operate continuously at exactly 232 psi or that every PN25 valve can operate continuously at 363 psi.

The governing valve standard, material, temperature, maximum differential pressure, pressure surges, flange design and manufacturer’s pressure-temperature data must also be checked.

Quick PN16 to PSI and PN25 to PSI Answer

For everyday purchasing and site discussions:

PN16 ≈ 232 psi
PN25 ≈ 363 psi

For technical specifications and purchase orders, retain the original PN designation and include the applicable valve and flange standards. Do not replace “PN16” with only “232 psi” or “PN25” with only “363 psi.”

How to Convert PN to PSI

The number following PN is commonly associated with a nominal pressure value in bar. To perform a basic PN to psi conversion, multiply that number by 14.5038.

PN16 Pressure in PSI

The calculation for PN16 is:

16 × 14.5038 = 232.0608 psi

Rounded values:

• One decimal place: 232.1 psi
• Whole number: 232 psi
• Approximate site value: 230 psi

The more accurate 232.1 psi value should be used in conversion tables. A rounded 230 psi value may be convenient in conversation but should not replace the specified pressure class in engineering documentation.

PN25 Pressure in PSI

The calculation for PN25 is:

25 × 14.5038 = 362.595 psi

Rounded values:

• One decimal place: 362.6 psi
• Whole number: 363 psi
• Approximate site value: 360 psi

Therefore, the correct answer for PN25 pressure in psi is approximately 362.6 psi—not 250 psi.

PSI to Bar Formula

When a project specification is written in psi and the valve catalogue uses bar, reverse the calculation:

Pressure in bar = pressure in psi ÷ 14.5038

Examples:

• 150 psi ÷ 14.5038 = 10.34 bar
• 200 psi ÷ 14.5038 = 13.79 bar
• 250 psi ÷ 14.5038 = 17.24 bar
• 300 psi ÷ 14.5038 = 20.68 bar

This reverse conversion is particularly useful when evaluating American-style pressure data against a PN16 or PN25 valve specification.

Common PSI to Bar Valve Conversion Table

The last column is only an initial comparison. Final valve selection must account for the complete pressure and temperature conditions rather than the normal gauge pressure alone.

PN16 and PN25 in Water Head

Water pipeline engineers sometimes work with metres of water column instead of bar or psi.

At standard conditions:

1 bar ≈ 10.197 metres of water head

Therefore:

• PN16 nominal reference: 16 × 10.197 ≈ 163.2 metres of water head
• PN25 nominal reference: 25 × 10.197 ≈ 254.9 metres of water head

Water-head values change slightly with water density, temperature and local gravity. They should be used as convenient hydraulic references rather than exact valve selection limits.

What Does PN Mean on a Valve?

PN means nominal pressure. More precisely, it is a standardized alphanumeric designation used to group the mechanical and dimensional characteristics of valves, flanges, pipes and other pressure-containing components.

The number following PN is dimensionless. Although it is commonly associated with a bar value for room-temperature water applications, PN should not be interpreted as a universal maximum allowable working pressure under every operating condition.

For example:

• PN16 is commonly associated with 16 bar or 232.1 psi.
• PN25 is commonly associated with 25 bar or 362.6 psi.
• The actual allowable pressure may change with valve material, temperature, design and product standard.

For a broader explanation of how metric and American pressure systems differ, see Norite’s guide to PN10, PN16, PN25 and Class 150 valve pressure ratings.

Nominal Conversion Is Not the Same as Allowable Working Pressure

The arithmetic conversion is exact, but the valve selection conclusion is not automatic.

Converting PN16 to 232.1 psi tells you the nominal relationship between 16 bar and psi. It does not independently confirm the valve’s maximum allowable pressure at the project temperature.

The usable pressure capability can be affected by:

• Body and bonnet material
• Valve design and wall thickness
• Maximum operating temperature
• Seat, seal, gasket and coating materials
• Applicable valve product standard
• Flange material and flange standard
• Maximum differential pressure across the closure
• Corrosion and erosion allowance
• Cyclic loading and required service life
• Manufacturer’s published pressure-temperature limits

A ductile iron resilient-seated water valve, a carbon steel ball valve and a stainless steel globe valve may all carry a PN16 marking while having different temperature, media and sealing limitations.

The manufacturer’s verified datasheet and the governing project standard take priority over a simple bar to psi valve conversion.

PN16 Pressure in PSI: What Does 232 PSI Mean in Practice?

PN16 is one of the most widely specified pressure classes for municipal water, water treatment, irrigation, HVAC and general utility pipelines.

Its nominal conversion is:

PN16 = 16 bar = 1.6 MPa = 1,600 kPa = 232.1 psi

PN16 valves are often considered for:

• Municipal water distribution
• Water treatment plant pipelines
• Irrigation networks
• Building water services
• HVAC cooling-water loops
• Moderate-pressure pump stations
• Fire-water and utility-water systems
• General industrial water service

These are typical applications, not automatic approvals. A pump discharge line operating at only 140 psi during normal flow may still experience a much higher pressure when the pump reaches shut-off head or when a valve closes rapidly.

A PN16 valve should therefore be checked against the highest credible pressure at its actual installation point.

PN25 Pressure in PSI: What Does 363 PSI Mean in Practice?

PN25 provides a higher nominal pressure reference:

PN25 = 25 bar = 2.5 MPa = 2,500 kPa = 362.6 psi

PN25 valves may be considered for:

• High-head pump discharge lines
• High-rise building pressure zones
• Long-distance transmission mains
• Mountainous pipelines with large elevation differences
• High-pressure irrigation stations
• Industrial process-water systems
• Pressure reducing valve stations with high inlet pressure
• Water systems where verified transient pressure exceeds PN16 capability

A PN25 designation does not mean the valve is suitable for every 25-bar application. Continuous operation near the nominal reference deserves a detailed engineering review, including the valve standard, temperature, material, seat design, differential pressure and surge conditions.

For a more detailed examination, read the guide to PN25 pressure ratings, valve selection and flange matching.

PN16 vs PN25 Pressure Comparison

PN25 has a higher nominal pressure class, but it is not automatically the best choice for every pipeline. Higher-rated valves can increase body weight, flange thickness, actuator torque, installation load, spare-parts complexity and purchase cost.

The better decision is the lowest verified pressure class that safely covers the complete operating envelope and complies with the project standard.

Norite’s PN10 vs PN16 vs PN25 valve selection guide provides a deeper application comparison.

PN16 Is Not 160 PSI

One of the most common conversion mistakes is reading the number 16 as if it were a shortened psi value.

PN16 does not mean 160 psi.

The correct nominal conversion is:

PN16 = 16 bar ≈ 232.1 psi

A pressure of 160 psi equals approximately 11.03 bar, which is below the nominal PN16 reference.

This does not mean that every PN16 valve is automatically approved for a 160 psi system. Maximum temperature, surge pressure, pump shut-off pressure, valve standard and material still need to be verified.

PN25 Is Not 250 PSI

PN25 does not mean 250 psi.

The correct nominal conversion is:

PN25 = 25 bar ≈ 362.6 psi

By comparison:

250 psi ≈ 17.24 bar

Therefore, a “250 PSI” valve marking and a “PN25” valve marking should not be treated as equivalent.

A manufacturer may list PN16, PN25, 200 PSI, 250 PSI and 300 PSI as separate available configurations. Buyers should confirm which exact configuration, standard, body design and flange drilling are included in the quotation.

PN16 and PN25 Are Not Direct ASME Class Equivalents

PN and ASME Class use different rating systems.

A Class 150 marking does not mean that the valve is limited to 150 psi. Its allowable pressure depends on material and temperature according to the applicable ASME pressure-temperature table.

Similarly, PN16 and PN25 should not be converted directly into Class 150 or Class 300 based only on approximate psi values.

When a project follows ASME requirements, check the specified material group, pressure-temperature table, valve standard and ASME flange dimensions. Do not substitute a PN valve simply because its converted psi value appears close.

The Norite valve standards guide explains the roles of EN, AWWA, API and ISO requirements in international valve projects.

PSIG vs PSIA: Confirm Which PSI Value the Project Uses

Valve pressure comparisons normally involve gauge pressure, often written as psig or psi(g). Absolute pressure is written as psia or psi(a).

At approximately sea-level atmospheric pressure:

psia ≈ psig + 14.7 psi

For example:

• 200 psig is approximately 214.7 psia.
• 200 psia is approximately 185.3 psig.

Do not compare a psia process value directly with a valve rating expressed as gauge pressure. The project datasheet should clearly identify whether the pressure is gauge or absolute, especially for vacuum, gas and process applications.

Pressures to Check Before Choosing PN16 or PN25

Normal operating pressure is only one part of the selection calculation. The valve should be checked against the full pressure envelope at its actual location.

Normal Working Pressure

This is the pressure expected during normal system operation. It is useful for understanding routine loading but should not be the only selection value.

Maximum Static Pressure

Static pressure may increase at low points in the pipeline, during low-demand periods or when downstream valves are closed.

For water systems, elevation has a direct effect. A valve at the bottom of a long descending pipeline can experience substantially more static pressure than a valve near the top.

Pump Shut-Off Pressure

When a centrifugal pump operates against a closed discharge, the pressure can rise above the normal duty-point pressure. The shut-off head should be obtained from the approved pump curve.

Surge Pressure and Water Hammer

Rapid valve operation, pump trips, check-valve slam and sudden flow changes can generate transient pressure peaks.

Installing a higher PN valve without analysing the surge source is not a complete water-hammer solution. Valve closing time, check-valve behaviour, air valves, surge vessels and pipeline profile may also need to be reviewed.

Maximum Differential Pressure

The valve body may see the full internal line pressure, while the disc, wedge, plug or trim may be loaded by the pressure difference across the closed valve.

This is particularly important for:

• Butterfly valve disc and shaft sizing
• Gate valve stem and operating torque
• Check valve closure behaviour
• Pressure reducing valve trim and cavitation risk
• Control valve actuator sizing

Hydrostatic Test Pressure

Pipeline or valve test pressure may be higher than the normal working pressure for a limited test duration. This does not mean the component is approved for continuous service at the test pressure.

The test pressure must be checked against the governing product and testing standards. Norite’s guide to valve hydrostatic testing, shell testing and seat testing explains these distinctions in more detail.

Practical PN16 Selection Example

Consider a municipal pump discharge line with the following conditions:

• Normal operating pressure: 110 psi
• Maximum static pressure: 145 psi
• Pump shut-off pressure: 175 psi
• Calculated surge pressure: 205 psi
• Maximum water temperature: 40°C
• Flange system: EN metric flanges

The highest credible service pressure is 205 psi, not the 110 psi normal operating pressure.

Since PN16 converts nominally to 232.1 psi, PN16 may be a candidate. However, it should only be accepted after confirming:

• The valve’s verified pressure-temperature capability
• Permitted occasional or surge pressure
• Applicable valve product standard
• Maximum differential pressure
• PN16 flange standard and dimensions
• Seat and seal temperature limits
• Project design margin and local code requirements

The conversion supports the initial comparison, but it does not replace the final engineering review.

Practical PN25 Selection Example

Consider a high-rise water pressure zone with:

• Normal pressure: 165 psi
• Maximum static pressure: 195 psi
• Pump shut-off pressure: 230 psi
• Calculated surge pressure: 275 psi
• Maximum temperature: 35°C

A PN16 nominal reference of 232.1 psi is below the calculated 275 psi surge pressure. PN16 should therefore not be selected from the normal-pressure value alone.

PN25, with a nominal conversion of 362.6 psi, may provide a suitable pressure-class basis. The final decision still requires verification of the valve standard, allowable surge condition, flange system, body material, seat design and all connected components.

Pressure Reducing Valve Example

Suppose a PRV station receives water at a maximum inlet pressure of 300 psi and reduces it to 90 psi downstream.

The selection must consider:

• 300 psi upstream body pressure
• Approximately 210 psi differential pressure under the stated condition
• Minimum and maximum flow
• Required downstream control range
• Cavitation risk
• Maximum inlet pressure during pump shut-off
• Potential surge pressure
• Valve and actuator operating limits

Although 300 psi is below the nominal PN25 conversion of 362.6 psi, that comparison alone does not size the PRV or confirm its trim suitability.

A pilot-operated pressure reducing valve should be selected from the complete pressure, flow and cavitation conditions.

Temperature Changes the Allowable Pressure

Valve pressure capability is linked to temperature because body materials, elastomeric seats, packing, gaskets and coatings do not retain identical performance across all temperatures.

For ambient-temperature water service, the nominal PN-to-psi conversion is a useful starting point. For hot water, steam, thermal oil, gas or chemical service, request the actual pressure-temperature data for the offered valve.

Do not assume that:

• A PN16 valve remains suitable for 232 psi at every temperature.
• A PN25 valve remains suitable for 363 psi at every temperature.
• A metal valve body guarantees that its seat and seals are also suitable.
• Two valves with the same PN marking have identical temperature limits.
• A Class rating and a PN rating derate along the same curve.

The lowest-rated pressure-containing or sealing component determines the practical limit of the assembled valve.

Can PN16 and PN25 Flanges Connect?

Do not assume that a PN16 valve can be installed between PN25 pipeline flanges or that a PN25 valve will directly replace a PN16 valve.

Depending on nominal diameter, material and flange-standard series, the two pressure classes may have differences in:

• Flange outside diameter
• Pitch circle diameter
• Bolt-hole quantity
• Bolt-hole diameter
• Flange thickness
• Facing dimensions
• Gasket seating area
• Bolt size and length

Some selected sizes may appear similar, but that does not establish universal compatibility.

Before ordering a replacement valve, confirm:

1. Nominal diameter or NPS
2. Full flange standard and relevant part
3. PN designation
4. Flange type and facing
5. Outside diameter
6. Pitch circle diameter
7. Bolt-hole quantity and diameter
8. Face-to-face dimension
9. Gasket specification
10. Approved dimensional drawing

Even if a higher-rated valve can be physically installed, a connected PN16 pipe, flange, dismantling joint or fitting may remain the pressure-limiting component.

Valve Type Also Affects Pressure Selection

The same PN designation does not make all valve types interchangeable.

Gate Valves

Gate valves are commonly used for full-open or full-closed pipeline isolation. Check body pressure, closed-valve differential pressure, stem loading, wedge design and operating torque.

Norite’s Z45X resilient seated gate valve is available in multiple pressure configurations for municipal water and wastewater projects.

Butterfly Valves

Butterfly valve selection should consider disc strength, shaft sizing, seat design and actuator torque. A larger differential pressure can substantially increase the torque required to open the valve.

Check Valves

Check valves must withstand system pressure while also closing reliably under reverse flow. Pump trips and rapid flow reversal can produce slam and water hammer even when normal pressure is moderate.

Pressure Reducing and Control Valves

PRVs and control valves require hydraulic sizing. Inlet pressure, outlet pressure, flow range, differential pressure, velocity, noise and cavitation can be more restrictive than the nominal body pressure class.

Common PN-to-PSI Conversion Mistakes

Mistake 1: Reading PN16 as 160 PSI

PN16 equals approximately 232.1 psi, not 160 psi.

Mistake 2: Reading PN25 as 250 PSI

PN25 equals approximately 362.6 psi, not 250 psi.

Mistake 3: Replacing the PN Designation with a Rounded PSI Value

“232 psi valve” does not fully define a PN16 valve, and “363 psi valve” does not fully define a PN25 valve. The applicable product and flange standards are still required.

Mistake 4: Selecting from Normal Pressure Only

Static pressure, pump shut-off head, surge pressure and test pressure may all exceed normal operating pressure.

Mistake 5: Treating Test Pressure as Continuous Working Pressure

A short-duration hydrostatic test does not authorize continuous operation at the same pressure.

Mistake 6: Assuming PN25 Is Always Better

PN25 may increase weight, torque, cost and flange requirements without solving surge, cavitation or material-compatibility problems.

Mistake 7: Upgrading Only the Valve

A PN25 valve installed between PN16 flanges does not upgrade the entire pipeline to PN25. Every pressure-containing component must be checked.

Mistake 8: Confusing PN with ASME Class

PN16 is not automatically Class 150, and PN25 is not automatically Class 300.

Mistake 9: Ignoring PSIG and PSIA

Gauge and absolute pressure values cannot be compared without identifying their reference basis.

Mistake 10: Accepting a Catalogue Rating Without the Exact Configuration

A supplier may offer the same valve model in PN16, PN25, 200 PSI, 250 PSI and 300 PSI versions. The quotation must identify the exact construction being supplied.

PN16 and PN25 Valve RFQ Checklist

Include the following information when requesting a quotation:

• Valve type and required function
• Nominal diameter or NPS
• Required PN designation
• Normal operating pressure
• Maximum static pressure
• Pump shut-off pressure
• Calculated surge pressure
• Pipeline test pressure
• Maximum differential pressure
• Minimum and maximum temperature
• Fluid and concentration
• Minimum, normal and maximum flow
• Body, trim, stem, seat and gasket materials
• Full flange standard, type and facing
• Face-to-face standard
• Manual, gearbox, pneumatic or electric operation
• Required shutoff or leakage class
• Coating and drinking-water approval requirements
• Inspection and test standard
• Material certificates and test reports
• Project quantity and delivery destination

A clear RFQ statement could read:

DN300 resilient-seated gate valve, PN16, flanged to the specified EN standard, ductile iron body, EPDM wedge, maximum working pressure 12 bar, maximum surge pressure 14.5 bar, water at 40°C, gearbox operated, required with approved drawings, material certificates and pressure-test reports.

This is much safer than requesting only “DN300 PN16 valve.”

Frequently Asked Questions

What is PN16 pressure in psi?

PN16 converts nominally to approximately 232.1 psi. It is commonly rounded to 232 psi.

What is PN25 pressure in psi?

PN25 converts nominally to approximately 362.6 psi. It is commonly rounded to 363 psi.

How do you convert PN to psi?

For a basic nominal conversion, multiply the associated bar value by 14.5038.

PSI = bar × 14.5038

Is PN16 equal to 160 PSI?

No. PN16 is commonly associated with 16 bar, which equals approximately 232.1 psi. A pressure of 160 psi equals about 11.03 bar.

Is PN25 equal to 250 PSI?

No. PN25 is commonly associated with 25 bar or approximately 362.6 psi. A pressure of 250 psi equals approximately 17.24 bar.

Can a PN16 valve operate continuously at 232 psi?

Not automatically. Confirm the applicable valve standard, material, temperature, pressure-temperature data, differential pressure, surge conditions and manufacturer’s verified rating.

Can a PN25 valve operate continuously at 363 psi?

Not automatically. The converted value is a nominal reference. Continuous operation near the nominal limit requires detailed verification.

Is PN25 stronger than PN16?

PN25 represents a higher nominal pressure class. However, actual valve suitability still depends on design, material, temperature, valve type and applicable standards.

Is PN16 the same as Class 150?

No. They use different rating systems and may use different flange dimensions. Similar pressure capability in a specific material and temperature range does not make them interchangeable.

What PN rating should be used for 200 psi?

A pressure of 200 psi equals approximately 13.79 bar, which is below the nominal PN16 reference of 16 bar. However, final selection must include maximum static pressure, pump shut-off pressure, surge, temperature, test pressure and the verified valve rating.

Can a PN25 valve replace a PN16 valve?

Possibly, but not automatically. Check flange dimensions, face-to-face length, gasket, bolt pattern, operating torque, connected-component ratings and project approval requirements.

Does PSI determine the flange drilling?

No. Pressure conversion alone does not define flange dimensions. The flange standard, nominal diameter, PN or Class designation, material series and flange type must be specified.

Final PN16 and PN25 Selection Checklist

Before approving a valve, confirm that:

• PN16 has been converted as approximately 232.1 psi.
• PN25 has been converted as approximately 362.6 psi.
• The original PN designation remains on the datasheet and purchase order.
• Gauge and absolute pressures are not being confused.
• Normal, static, shut-off, surge and test pressures have all been reviewed.
• Maximum differential pressure has been checked.
• Temperature and media are within the material and seal limits.
• The pressure-temperature capability is documented.
• Valve and flange standards are clearly identified.
• Flange drilling and face-to-face dimensions match the pipeline.
• Every connected component has a suitable pressure rating.
• Required pressure tests and certificates are included in the order.

Conclusion

The direct conversion is simple: PN16 is approximately 232 psi, and PN25 is approximately 363 psi. The important purchasing decision begins after that calculation.

A converted psi value helps engineers compare documents written in different units, but it does not replace the valve standard, material specification, pressure-temperature rating or full system-pressure review. Normal pressure, pump shut-off head, water hammer, differential pressure, testing conditions and flange compatibility must all be considered before choosing between PN16 and PN25.

If you need a PN16 or PN25 gate valve, butterfly valve, check valve, pressure reducing valve or matching pipeline component, contact Norite with your DN, fluid, operating pressure, surge pressure, temperature, flange standard and project drawings. Our team can review the complete operating conditions and prepare a project-specific valve configuration and quotation.