How to Choose the Right Butterfly Valve Pressure Rating

May 29, 2026
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When selecting a butterfly valve, pressure rating is one of the most important factors to consider. Whether the valve is used in an HVAC system, a chilled water network, a water treatment facility, or an industrial pipeline, choosing the wrong pressure rating can lead to leakage, equipment damage, and even unexpected system downtime.

In this article, we'll explain the most common butterfly valve pressure ratings, including PN10, PN16, Class 150, and Class 300, and help you determine which option is best suited to your specific application.

What Is a Butterfly Valve Pressure Rating?

A butterfly valve pressure rating indicates the maximum pressure the valve is designed to handle safely under specified operating conditions. It is an important factor engineers and buyers use to determine whether a valve is suitable for a particular piping system.

The pressure rating of a butterfly valve is influenced by several factors, including valve design, body material, seat material, and operating temperature. Selecting the appropriate pressure rating helps ensure reliable sealing performance, safe operation, and a longer service life.

Why Are There Different Pressure Rating Systems?

Two major pressure rating systems are commonly used in the global valve industry: PN (Pressure Nominal) and Class.

PN Pressure Rating System

The PN system is widely used in European and international standards, including DIN, EN, and ISO standards.

The number following PN generally indicates the nominal pressure rating of the valve at approximately 20°C, expressed in bar.

For example:

PN10 = approximately 10 bar
PN16 = approximately 16 bar

Class Pressure Rating System

The Class system is primarily used in ANSI and ASME standards. Unlike the PN system, the number following Class does not represent the actual pressure value.

For example:

Class 150 ≠ 150 psi
Class 300 ≠ 300 psi

Instead, Class refers to a pressure-temperature rating defined by ASME standards. The allowable working pressure varies depending on the valve material and operating temperature.

Although both systems are used to indicate a valve's pressure capability, they are based on different standards and rating methods. As a result, PN ratings and Class ratings cannot be directly converted or considered equivalent

Common Butterfly Valve Pressure Ratings

For most water treatment, HVAC, and industrial applications, the following are the most commonly used butterfly valve pressure ratings:

Pressure Rating	Approximate Pressure	Typical Applications
PN10	10 bar (145 psi)	HVAC systems, chilled water systems, building water services
PN16	16 bar (232 psi)	Water treatment, municipal water supply, cooling tower systems
Class 150	19.6 bar (285 psi)	Industrial piping, process water systems
Class 300	51 bar (740 psi)	High-pressure industrial systems, power generation, and petrochemical applications

Among these ratings, PN16 and Class 150 are the most widely used butterfly valve pressure ratings worldwide.

What Is the Difference Between PN10 and PN16 Butterfly Valves?

The main difference between PN10 and PN16 butterfly valves is their pressure rating.

For building water systems and HVAC applications, PN10 and PN16 are the two most commonly used options.

PN10 has a nominal pressure rating of 10 bar and is typically used in lower-pressure systems.
PN16, on the other hand, is rated for 16 bar and provides a greater safety margin.

Based on practical project experience, more and more engineers and contractors are choosing PN16 as the standard specification. The reason is simple: the cost difference between PN10 and PN16 is usually relatively small, while PN16 offers higher pressure capacity and a wider range of applications.

As a result, PN16 has become the preferred choice for many systems, including:

Chilled water systems
Cooling tower systems
Water treatment systems
Municipal water supply systems

If the project budget allows, PN16 is often considered the safer and more versatile option.

What Is the Pressure Rating of PN16 vs Class 150?

PN16 and Class 150 are often compared because their pressure ratings appear relatively close. However, they belong to two different pressure rating systems and are not the same.

PN16: Part of the EN, DIN, and ISO pressure rating system, PN16 indicates a nominal pressure rating of approximately 16 bar under normal temperature conditions.
Class 150: Class 150 is not a fixed pressure value. It belongs to the ANSI and ASME pressure–temperature rating system, where the allowable working pressure varies depending on the valve material and operating temperature.

For typical carbon steel valves at ambient temperature, the allowable working pressure of Class 150 is approximately:

285 psi (19.6 bar)

Therefore, in terms of pressure-handling capability at normal temperature, Class 150 generally provides a slightly higher pressure rating than PN16.

Can PN16 Replace Class 150?

Not necessarily.

Although some dimensions may appear similar, PN16 flanges and Class 150 flanges are designed according to different standards and have several important differences, including:

Bolt hole dimensions
Number of bolt holes
Flange thickness
Facing dimensions
Flange outside diameter (OD)

Because of these differences, a PN16 butterfly valve cannot always be directly installed in a Class 150 piping system. In many cases, flange compatibility must be verified, or a transition flange may be required.

What Is the Difference Between Class 150 and Class 300?

The main difference between Class 150 and Class 300 is their pressure-handling capability.

For typical carbon steel valves at ambient temperature:

Class 150 has an allowable working pressure of approximately 285 psi
Class 300 has an allowable working pressure of approximately 740 psi

This means a Class 300 butterfly valve can withstand significantly higher system pressures and is generally better suited for high-pressure industrial applications.

However, a higher pressure rating does not always mean a better choice. Compared with Class 150 valves, Class 300 butterfly valves are typically:

Heavier
Larger
More expensive
More difficult to install

As a result, using a Class 300 butterfly valve in a low- or medium-pressure system can often lead to unnecessary project costs without providing any practical benefit.

butterfly valve

How to Choose the Right Butterfly Valve Pressure Rating

When determining the required pressure rating, factors such as system design pressure, operating temperature, pressure fluctuations, and the applicable piping standard (EN/DIN or ANSI/ASME) should all be taken into consideration.

The table below provides general recommendations for common applications:

Application	Common Pressure Rating
HVAC Systems	PN10 / PN16
Chilled Water Systems	PN16
Cooling Tower Systems	PN16
Municipal Water Supply Systems	PN16 or Class 150
Data Center Cooling Systems	PN16 or Class 150
Industrial Process Systems	Class 150
High-Pressure Industrial Systems	Class 300

In many water treatment, chilled water, cooling tower, and municipal water projects, PN16 has become the most commonly specified pressure rating. For ANSI piping systems, Class 150 is typically the standard choice, while Class 300 is generally reserved for higher-pressure industrial applications.

Conclusion

Selecting the right butterfly valve pressure rating is essential for ensuring safe and reliable system operation. For most HVAC, chilled water, cooling tower, water treatment, and municipal water applications, PN16 is capable of meeting the requirements of the vast majority of systems. Class 150 and Class 300 are more commonly used in ANSI piping systems and higher-pressure industrial applications.

As a professional industrial valve manufacturer, Union Valve offers butterfly valves in PN10, PN16, Class 150, and Class 300 pressure ratings for HVAC systems, water treatment plants, cooling systems, municipal water networks, and industrial piping applications. Choosing the appropriate pressure rating based on actual operating conditions can help improve system reliability while keeping overall project costs under control.You can contact us at any time.