Bray Make Control Valve

Selecting & Sizing Control Valves  Selecting the appropriate control valve is essential to achieve optimal process control performance. Beyond simply identifying the correct valve type that aligns with the flow characteristics of the process, its crucial to recognize control valves as comprehensive systems. These systems encompass not only the valve itself but also the actuator, valve controller, and sensors that provide process condition feedback.   To achieve accurate sizing, follow these general steps: 1. Collect Process Control Parameters including details about the control precision, repeatability, rangeability, actuation speed requirements for response to conditions (which affects actuation choice). precision of control, dynamic response to fluctuations in process conditions, potential for upset conditions and noise attenuation requirements. 2. Obtain process condition specifications including the media type, viscosity, the presence of suspended solids (such as abrasive media), temperature of the process, pressure, flow velocity, pressure drop across the orifice, and the risk of erosion from cavitation, flashing, and solids. 3. Include additional information such as pipe size, pressure class, valve and or pipeline, requirements for materials of construction, trim, and coatings. 4. Be sure to include factors such as delivery time, maintenance intervals, longevity requirements of the valve, economic restrictions, plant outage schedules, and maintenance plans that could affect the life of the valve. Process control precision and rangeability are two of the most important factors that determine the type of valve and actuation package required. Therefore, fine control and coarse control applications may need different solutions Data Description Control valve function The purpose of the control valve in the process, such as daily start up, continuous or batch control, duration at min flow, etc. Process data The data for the normal, maximum, and minimum flow conditions, such as fluid name and properties, pressure inlet and outlet, temperature, etc. Performance requirement The process conditions that define the desired performance of the control valve, such as rangeability, accuracy, repeatability, responsiveness, etc. Service life expectation The expected lifespan of the control valve under severe duty conditions, such as erosion, corrosion, cavitation, flashing, noise, etc. Air supply or voltage The available air supply or voltage for the actuation and accessories of the control valve, such as pneumatic, hydraulic, or electric actuators, positioners, solenoids, limit switches, etc. Fluid name and properties The name and properties of the fluid that flows through the control valve, such as density, viscosity, vapor pressure, specific heat, etc. Line size The size of the upstream and downstream pipes that connect to the control valve, such as diameter, length, etc. Pipe schedule The schedule of the upstream and downstream pipes that connect to the control valve, which indicates the wall thickness and pressure rating of the pipes. Temperature The minimum, normal, and maximum temperature of the fluid that flows through the control valve. Upstream pressure The minimum, normal, and maximum pressure of the fluid before it enters the control valve. Downstream pressure The minimum, normal, and maximum pressure of the fluid after it exits the control valve.