Control Valves: 5 Myths That Still Confuse EngineersÂ
Introduction
Control valves are part of almost every industrial process, even if they don’t always get much attention. They regulate flow, pressure, and temperature - basically keeping systems stable and running as expected.
But here’s the issue: many engineers still rely on assumptions that don’t always hold up in real operating conditions. These ideas often come from past practices or simplified rules of thumb. The problem is, even small misunderstandings can affect performance, increase maintenance, and lead to avoidable failures. Let’s walk through a few common myths that still circulate - and why they deserve a second look.
Myth 1: Bigger Valves Perform Better
It’s easy to assume that a larger valve gives you more capacity, so it must be the safer option. But in practice, that’s not how it works.
When a valve is oversized, it usually operates close to the shut position most of the time. That makes precise control difficult and can introduce instability into the process. Over time, this can lead to common valve issues such as vibration, noise, and faster wear of internal parts. Instead of improving performance, an oversized valve often makes the system harder to manage.
What actually works: A properly sized valve - one that operates in its optimal range (typically around 70–90% open at maximum flow) - delivers far better control and stability.
Myth 2: All Control Valves Work the Same Way
At a glance, most control valves may look similar. But their internal design and behaviour can vary significantly depending on the types of control valves used in industrial applications.
For example, globe valves are known for precise control, while butterfly valves are often used for larger flow applications with lower pressure drops. Plug and segmented valves offer different advantages depending on the process conditions.
Choosing the wrong type can lead to inefficient operation or poor control performance. A valve that works well in one application may not suit another at all.
Takeaway: Valve selection should always be based on the specific process, not just availability or familiarity.
Myth 3: Control Valves Only Control Flow
Flow control is just one part of what control valves do. In many systems, they also play a key role in managing pressure, temperature, and even liquid levels.
Take steam systems, for example. Valves are used to regulate temperature by controlling steam flow. In pressure-sensitive systems, they help maintain balance by adjusting to pressure changes.
 Looking at them as “flow-only” devices can lead to underestimating their importance in overall system performance.
What to keep in mind:
Control valves are central to maintaining process stability - not just flow regulation.
Myth 4: Maintenance Is Only Needed After Failure
In many plants, maintenance still happens only after something goes wrong. The valve is left alone until performance drops or a failure occurs, often due to a lack of structured maintenance practices.
The issue is that by the time a problem becomes visible, internal damage is often already advanced. Components like trims, seals, and actuators wear out gradually, not suddenly. Ignoring early signs can lead to unplanned downtime, safety concerns, and higher repair costs.
A better approach: Regular inspection and preventive maintenance help catch issues early and keep the system running reliably.
Myth 5: Valve Selection Is Just About Size and Pressure Rating
Size and pressure rating are important - but they’re only part of the decision.
Other factors like flow characteristics, Cv value, material compatibility, and operating conditions play a major role in how a valve performs. In demanding environments - high temperature, corrosive media, or fluctuating conditions - these factors become even more critical.
Overlooking them can lead to poor control, shorter valve life, or issues like cavitation, which over time can result in cavitation damage to internal components.
The right approach: Valve selection should consider the full process environment, not just basic specifications.
Why These Myths Still Exist
These ideas didn’t appear out of nowhere. Many come from years of practical experience or standard practices that once worked well.
But processes evolve. What was acceptable earlier may not suit today’s operating conditions. There’s also a tendency to rely on past decisions or cost-driven choices instead of evaluating each application properly.
That’s how these myths continue to stick around.
What Engineers Should Do Instead
Moving away from assumptions and focusing on actual process data makes a significant difference.
Understanding flow behaviour, pressure conditions, and operating environments is essential. Proper sizing calculations and analysing valve characteristics can help avoid many common issues.
Working closely with experienced valve manufacturers also adds value, especially when dealing with complex or critical applications.
Also Read: Ways to Improve Control Valve Performance and Maximize Its EfficiencyÂ
Conclusion
Control valves might seem like standard components, but their impact on system performance is anything but small.
Relying on common myths can lead to inefficiencies, higher costs, and avoidable operational challenges. On the other hand, a better understanding of valve selection, sizing, and maintenance can improve both reliability and control.
Sometimes, it’s not about changing the system - it’s about changing the way we think about it.