How to determine the appropriate torque requirements for driving butterfly valves?- Kaixin Pipeline Technologies Co.,Ltd

Determining the appropriate torque requirements for driving butterfly valves involves considering several factors to ensure smooth operation and prevent issues such as over-torquing or under-torquing. Here's a step-by-step guide:

Identify Operating Conditions: Consider the nature of the fluid being controlled—whether it's a liquid or gas—as well as its properties such as viscosity and density, which impact flow dynamics and, consequently, torque requirements. Evaluate the anticipated flow rate to gauge the forces exerted on the valve during operation. Assess the operating pressure to understand the resistance the valve must overcome to control flow effectively. Account for temperature variations, as changes in temperature can affect material properties and alter fluid characteristics, thereby influencing torque demands. Anticipate any fluctuations or surges in operating conditions, as these transient events may impose additional torque requirements on the valve.

Consider Installation Orientation: The orientation in which the valve is installed significantly affects torque calculations. Horizontal installations typically experience uniform force distribution across the valve components. In contrast, vertical installations introduce gravitational forces that can vary torque requirements, especially during opening and closing operations. Inclined installations further complicate torque assessment, as gravitational and flow forces interact in complex ways. Therefore, carefully analyze the installation orientation to accurately predict torque needs and ensure positive valve performance under all operating conditions.

Calculate Seating Torque: Seating torque is the force required to overcome initial friction and properly seat the valve. This critical parameter ensures tight shut-off and prevents leakage when the valve is closed. To calculate seating torque, consider factors such as the material composition of the valve components, surface finishes, and seal designs. Analyze the contact area between the valve disc and seat to determine the frictional forces involved. Account for factors such as cold welding or stiction, which can increase seating torque and affect valve operability.

Determine Operating Torque: Operating torque represents the force needed to sustain valve movement during continuous operation. Calculate operating torque based on the flow characteristics of the system, including pressure differentials, flow velocities, and fluid properties. Evaluate the resistance offered by the valve design, such as disc shape, seal type, and flow path geometry. Consider the effects of fluid turbulence, cavitation, and erosion on torque requirements. Factor in dynamic forces, such as water hammer or surge pressures, to ensure the valve can withstand transient loads without compromising performance.

Factor in Safety Margin: Incorporating a safety margin into torque calculations is essential to account for uncertainties and variations in operating conditions. The safety margin serves as a buffer against unexpected events, such as system upsets, material degradation, or design flaws. Assess the criticality of the valve application and the consequences of valve failure to determine an appropriate safety margin. Consider industry practices and regulatory requirements when establishing safety factors. Balance the need for reliability with the desire to minimize over-engineering and associated costs. Conduct sensitivity analyses to assess the impact of varying parameters on torque requirements and refine safety margin estimates accordingly.

CPVC Type B Handle Butterfly Valve DN40-200