Choosing the right valve for your system starts with knowing how much pressure it can handle. The pressure rating tells you the maximum pressure a valve can manage without risk of leaking, failing or bursting, all of which are serious concerns in sectors like oil and gas, power generation, or industrial processing.

The trouble is, pressure ratings are labelled in different ways depending on where you’re sourcing the equipment. To make things clearer, here’s what the main systems, ANSI and PN, really mean, and how to compare them.

What Is a Valve Pressure Rating?

A valve’s pressure rating is the maximum pressure it can safely manage, typically in relation to temperature. If your system goes beyond that limit, the valve could leak or fail entirely, which can be dangerous in systems handling steam, gas or hazardous materials.

Pressure and temperature are closely linked. A valve rated for one pressure at 20°C might not perform the same way at 200°C. That’s why temperature matters just as much as pressure when checking specifications.

The ANSI Pressure Class System

The ANSI (American National Standards Institute) pressure class system is widely used in industries where higher pressures and temperatures are the norm. Instead of listing a set pressure, it uses a classification system that ties into a pressure–temperature chart.

You’ll often see ANSI Classes 150, 300, 600, 900, 1500, and 2500. For example, a Class 150 valve might be suitable for about 19 bar at room temperature, while a Class 600 valve could be used for more than 100 bar, depending on the valve’s material and how hot the system gets. That’s why it’s important to check the full chart, not just the class number.

For high-pressure environments, ball valves are a common choice due to their robust design and excellent sealing performance, particularly when matched to the correct ANSI pressure class.

The PN Rating System

The PN (Pressure Nominal) system is used more often in the UK and Europe, especially for water, HVAC, and general industrial setups. PN ratings are simpler: they’re based on the pressure the valve can handle at 20°C.

So a PN16 valve is built to work with 16 bar of pressure at that temperature. The system is easier to follow for lower-pressure jobs, and the ratings are consistent across different materials. Common PN classes include PN10, PN16, PN25 and PN40. Higher ratings like PN100 exist, but are used less often.

PN valves are solid for everyday applications, but they’re not made for very high temperatures or extreme pressure. That’s where ANSI valves are a better option.

Comparing ANSI and PN Ratings

The key difference is how pressure tolerance is calculated. ANSI ratings take both pressure and temperature into account, which makes them more flexible in high-temperature environments. PN ratings are set values at room temperature, so they’re better suited to low-temperature, stable conditions. In moderate-pressure systems such as water or HVAC, butterfly valves with PN ratings are often the preferred solution, offering efficient control with minimal space requirements.

If your project involves mixing equipment from Europe and the US, you’ll need to match up flanges, pressure classes, and connection types carefully, or you’ll run into compatibility problems.

Choosing the Right Pressure-Rated Valve

To make the right choice, you need a clear picture of your system. That includes the max pressure and temperature, the fluid or gas running through it, how often the valve will be used, and whether it’s manual or automated. The choice of material also plays a vital role. Cast steel valves are commonly used in high-pressure environments due to their strength and durability across a range of temperatures.

Picking the wrong pressure rating can lead to breakdowns, wasted energy, and safety risks. A reliable valve supplier like JCV can help you avoid those issues, providing the right products, proper documentation, and technical support where it counts.

Trusted Advice and Fully Rated Valves from JCV

At John Clark Valves, we supply both ANSI and PN-rated valves for all kinds of jobs, from large-scale petrochemical projects to routine water and HVAC installations. With years of hands-on experience and a knowledgeable technical team, we’ll make sure your valves are fit for purpose, safe, and fully compliant.

Need help with international standards, a custom setup, or just a quick quote? Speak with our team today, we’re ready to help.