The butterfly valve, as a compact, quick-opening, and low-resistance regulating valve, is widely used in industries such as water supply and drainage, HVAC, power, chemical, and paper-making. However, in practical engineering applications, improper consideration of the butterfly valve’s installation direction and spatial arrangement often leads to valve operating abnormalities, decreased sealing performance, and deviations in control accuracy. In severe cases, it can even cause system failures or frequent maintenance, resulting in unnecessary economic losses. Therefore, a correct understanding of the impact of installation orientation and spatial layout on butterfly valve performance is essential to ensure its reliable operation and extend its service life.

1. The Impact of Installation Orientation on Butterfly Valve Performance

(1) Fluid Flow Direction and Its Effect on Sealing Performance

For centerline butterfly valves, where the valve disc rotates around the valve shaft, the force is relatively symmetric, and the fluid flow direction has little impact on the sealing performance. Therefore, the flow direction requirement is not strict during installation. However, for eccentric butterfly valves, especially double-eccentric and triple-eccentric types, the seal design is based on the "flow-assisted compression" principle. That is, when the medium pressure comes from the specified direction, it pushes the valve disc toward the sealing seat, thereby enhancing the sealing effect.

If the valve is installed in the opposite direction of the flow arrow marked by the manufacturer, the reverse fluid flow will wash the valve disc. Not only will the expected sealing effect not form, but it may also create gaps between the sealing surfaces, accelerate valve seat wear, and cause internal leakage, making it impossible to close the valve completely. Therefore, the installation of eccentric butterfly valves must strictly follow the flow direction requirements.

(2) Valve Shaft Orientation and Its Effect on Opening/Closing Torque and Actuator

The installation orientation of the valve shaft (horizontal or vertical) has a significant impact on the opening/closing performance, valve body stress, and actuator life. Most medium and small-sized butterfly valves are installed with the valve shaft in the horizontal position. This method facilitates the alignment of the valve body with the pipeline and the arrangement of the actuator.

However, for large-diameter butterfly valves or those installed in high locations or vertical pipelines, the valve shaft is often vertical. In this position, the weight of the valve disc directly acts on the valve shaft, especially when the valve disc is in the open position, where its center of gravity deviates from the axis, creating a large eccentric torque and increasing the axial load during opening and closing. If the actuator does not account for this additional load, it may result in poor opening/closing performance, motor or cylinder overloads, and other issues.

Moreover, in vertical installations, the weight of the valve disc may cause it to sag, and long-term operation may lead to uneven wear of the valve shaft and packing, accelerating sealing failure.

2. The Impact of Spatial Layout on Butterfly Valve Performance

(1) Adaptability to Pipeline Connection Structure

The butterfly valve body is typically connected using wafer, flanged, or lug-type connections. Different structures have varying space requirements for installation. In particular, wafer-type butterfly valves rely on the clamping force between the upper and lower flanges for installation. If the pipelines on both sides are not aligned or lack sufficient rigidity, it may lead to uneven stress on the valve body, affecting the centering of the sealing surfaces, causing leakage or operational difficulties.

During field installation, it is also important not to install the butterfly valve near pipe elbows, pump outlets, or tee connections. These areas have complex fluid flow patterns, significant pressure fluctuations, and are prone to vortex and oscillations, which can cause valve disc vibrations or frequent flushing of the sealing surfaces, shortening the valve's service life. It is recommended to leave a sufficient straight pipe section (usually 5-10 times the nominal diameter) between the butterfly valve and these components to ensure flow field stability.

(2) Space Reservation and Maintenance Convenience

When the butterfly valve opens and closes, the valve disc rotates in the pipeline, and its rotational space must be completely clear of surrounding components. If the installation space is insufficient, it may cause the valve disc to become obstructed, especially when the valve is fully open or closed. Additionally, sufficient installation and maintenance space should be reserved for actuators, as electric actuators, for example, generate heat during operation, and insufficient space may hinder heat dissipation.

When designing pipeline layouts, it is important to consider factors such as the valve installation depth, rotation diameter, operator hand wheel, and actuator size to avoid situations where the valve cannot be disassembled or replaced during maintenance.

(3) Coordination Between Butterfly Valve and Actuator Installation

For systems with a higher degree of automation, butterfly valves are typically paired with electric, pneumatic, or hydraulic actuators. When installing such actuators, special attention should be paid to aligning the drive direction with the valve shaft orientation, as misalignment may create eccentric torque, leading to abnormal actuator load.

The actuator body is usually heavy, so a stable bracket or platform should be provided to support it. This prevents the actuator's weight from acting on the valve body flanges or valve shaft, which could overload bearings or cause flange breakage.

3. Conclusions and Recommendations

The installation direction and spatial arrangement of butterfly valves have a direct impact on their operational performance, sealing effectiveness, and service life. Eccentric butterfly valves should be installed strictly according to flow direction requirements to avoid reverse fluid wash; the valve shaft orientation should be reasonably selected according to the medium properties and actuator layout; the layout should ensure sufficient valve rotation space and flow field stability, avoiding high-disturbance areas. During installation, pipeline alignment and secure connections must be ensured, and adequate space should be reserved for maintenance.

To ensure the reliable application of butterfly valves in engineering, it is recommended to communicate fully with valve manufacturers regarding selection and installation requirements during the design phase and strictly follow technical standards during construction and commissioning.