Butterfly Valves and Gate Valves Compared As Shutoff Valves

Shutoff valves provide an effective means of routing flows or isolating parts of your piping process for monitoring or maintenance.

But much like other stainless steel piping components, the types of valves you choose to use in your piping system will have a major impact on the performance and service life offered.

In this guide, we're going to compare two of the most common valve types used for on and off operation in modern processing systems.

By looking at the strengths and weaknesses of each design, you'll have a solid foundational understanding of the important characteristics of each valve type and be able to identify options applicable to your needs with greater certainty.

Butterfly Valves Types as Shutoff Valves

Butterfly valves utilize a flat disc attached to a stem to open or close the flow path.

Requiring only 90-degrees of movement to move from full-open to full-close, these valves are fast and easy to actuate.

The valve handle also provides fast verification of the valve's open or closed state, unlike some valves which rely on screw taps or handwheels for actuation.

When properly matched to the connecting pipe sizes, butterfly valves create minimal pressure drop and can allow nearly unimpeded flow through the valve.

However, as the disc sits perpendicular to the flow when open, a minor pressure drop and slight flow turbulence are unavoidable.

This also means that butterfly valves are not typically suited for use in processes involving suspended solids, grit, or stringy substances as they might accumulate on the disc and prevent a tight seal when attempting to close the valve.

The lack of flow restriction and quick actuation time also elevate the risk of fluid hammering.

If you plan to use butterfly valves in your piping system, designing with this risk in mind and careful actuation of the valves is critical to safe operation and minimizing damage risks.

While butterfly valves can operate in a partially opened or throttling state, long-term flow-throttling use is not recommended as the precision offered is not as good at alternatives such as needle valves.

Gate Valves Types as Shutoff Valves

Válvulas de compuerta feature a flat- or wedge-shaped gate on a threaded stem.

The design provides a means of linear actuation in which the gate moves into the flow path and seats into a recess opposite the stem, creating a strong seal.

When opened, it is completely out of the flow path, resulting in zero flow obstruction or pressure drop.

For processes involving slurries, suspended solids, or grit, knife gate valves are a specialized form of gate valve that features a bevelled edge on the gate.

This shape helps the gate cut through any build-up that might accumulate in the recess and reduce the amount of torque needed to fully close the gate.

Because the valve uses a linear actuation and threaded stem, moving from full-open to full-close states takes longer than most 90-degree actuation valve types, such as butterfly valves or plug valves.

However, this virtually eliminates any risk of fluid hammering.

When important, rising stem models of gate valves can also provide a quick visual indicator of the valve‘s state.

However, this comes at the cost of requiring more space above the valve to accommodate the rising stem.

When space is at a premium, non-rising stem designs are likely the better choice.

Most gate valve designs are not designed for use in a throttled state.

Extended throttling use can create vibrations and resonance, leading to damage to the valve internals, seals, gaskets, and other critical elements.

Gate valves also work best in high-pressure systems. Use in low-pressure systems where a tight seal is critical might require special accommodations as low-pressure operation might lead to seeping at the valve while closed.

The above content is a comparison of butterfly valves and gate valves compared as shutoff valves, It is provided by ZZJG Valve engineers. If you need to know more about this, please contact ZZJG Valve.