Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Control Valves and Actuators
…216 unchanged lines
## Final Control Element Function {toc}
−### The control valve shall be selected to modulate the controlled process variable (flow, pressure, level, or temperature) in response to the loop demand signal from the controller. {note}
+### The control valve shall be selected to modulate the controlled process variable (flow, pressure, level, or temperature) in response to the loop demand signal from the controller.
−### The valve assembly shall accept the controller output and position the valve so that the installed flow tracks the demand across the required operating range. {note}
+### The valve assembly shall accept the controller output and position the valve so that the installed flow tracks the demand across the required operating range.
### The controller output signal type and range shall be coordinated with [[sync/programmable-logic-controllers]] and the position feedback with [[sync/scada-and-hmi-systems]].
…20 unchanged lines
### The service fluid and its phase determine the sizing equations, the trim selection, and the material requirements. {note}
+### The service fluid, composition, and any solids or abrasive content shall be [[drawing: as indicated on the P&IDs and process datasheets]].
+
```datasheet
label: Service Fluid Type
…9 unchanged lines
```
−### The service fluid, composition, and any solids or abrasive content shall be [[drawing: as indicated on the P&IDs and process datasheets]].
−
# Valve Body Style {toc}
## Body Style Selection {toc}
−### The body style shall match the service, the required rangeability, the available pressure drop, and the cleanliness of the fluid. {note}
−### Globe (sliding-stem) valves provide precise throttling, high rangeability, and ready accommodation of anti-cavitation and low-noise trim, and are the default for clean modulating service where tight control matters. {note}
−### Segmented-ball valves provide high capacity and high rangeability with good shutoff, tolerate fiber and solids, and are common in pulp, sludge, and high-turndown liquid service. {note}
−### Eccentric rotary-plug valves combine rotary economy with globe-like control and good shutoff, and resist coating and scaling. {note}
−### High-performance (eccentric-disc) butterfly valves provide high capacity in large line sizes at low cost and are used for modulating control where the pressure drop is modest, including large water and wastewater flow control. {note}
+### The body style shall match the service, the required rangeability, the available pressure drop, and the cleanliness of the fluid.
```datasheet
…7 unchanged lines
default: "Globe — sliding stem, single or balanced cage trim"
```
+### Globe (sliding-stem) valves provide precise throttling, high rangeability, and ready accommodation of anti-cavitation and low-noise trim, and are the default for clean modulating service where tight control matters. {note}
+### Segmented-ball valves provide high capacity and high rangeability with good shutoff, tolerate fiber and solids, and are common in pulp, sludge, and high-turndown liquid service. {note}
+### Eccentric rotary-plug valves combine rotary economy with globe-like control and good shutoff, and resist coating and scaling. {note}
+### High-performance (eccentric-disc) butterfly valves provide high capacity in large line sizes at low cost and are used for modulating control where the pressure drop is modest, including large water and wastewater flow control. {note}
### The body style shall not be a quarter-turn isolation valve repurposed for throttling unless it is specifically the high-performance modulating type with a control-quality actuator and positioner.
…103 unchanged lines
### The process data set — flow, inlet pressure, pressure drop, temperature, and fluid properties at each flow case — is [[drawing: as indicated on the P&IDs and process datasheets]] and shall be provided to the valve manufacturer for sizing.
−### The pressure drop across the valve shall be the actual drop at each flow case, not an assumed fixed value; using an arbitrary fixed drop produces a mis-sized valve when the system curve is pump- or elevation-dominated. {note}
+### The pressure drop across the valve shall be the actual drop at each flow case, not an assumed fixed value; using an arbitrary fixed drop produces a mis-sized valve when the system curve is pump- or elevation-dominated.
# Flow Characteristic and Rangeability {toc}
…6 unchanged lines
### Quick-open trim produces large flow change for small initial travel and is not used for modulating control; it suits on-off and some self-acting service only. {note}
+### The characteristic shall be selected against the pressure-drop ratio (valve drop divided by system drop) at maximum flow: equal-percentage where that ratio is low, linear where it approaches unity.
+
```datasheet
label: Inherent Flow Characteristic
…7 unchanged lines
```
−### The characteristic shall be selected against the pressure-drop ratio (valve drop divided by system drop) at maximum flow: equal-percentage where that ratio is low, linear where it approaches unity.
−
### Specifying linear trim on a system where the valve takes only a small share of the pressure drop yields an installed characteristic that behaves like quick-open — most of the control occurs in the first portion of travel, and the loop is difficult to tune. {note}
…3 unchanged lines
### Higher rangeability lets one valve control a wider flow range without losing characterization at low travel. {note}
+### The valve rangeability shall equal or exceed the turndown required by the process operating cases.
+
```datasheet
label: Required Rangeability
…7 unchanged lines
```
−### The valve rangeability shall equal or exceed the turndown required by the process operating cases.
−
# Cavitation, Flashing, and Noise {toc}
…4 unchanged lines
### Flashing occurs when the outlet pressure remains below vapor pressure so the fluid stays partly vaporized downstream, eroding the body by high-velocity two-phase flow. {note}
+### The cavitation or flashing condition of the service shall be evaluated and specified, and the valve trim and body shall be selected accordingly.
+
```datasheet
label: Cavitation / Flashing Condition
…11 unchanged lines
### Where the service flashes, the valve body and trim shall be selected for the resulting two-phase erosion, with a hardened or hardfaced trim and an erosion-resistant body, and the body style shall direct the expanding flow away from the body wall.
−### Cavitation cannot be eliminated by trim material alone; if the pressure profile is not staged, even hardened trim erodes — the pressure drop must be managed, not merely resisted. {note}
+### Cavitation cannot be eliminated by trim material alone; if the pressure profile is not staged, even hardened trim erodes — the pressure drop must be managed, not merely resisted.
## Predicted Noise {toc}
### Predicted valve noise shall be calculated per IEC 60534-8-3 for compressible (aerodynamic) flow and IEC 60534-8-4 for liquid (hydrodynamic) flow. {note}
+### Predicted sound pressure level at 1 m from the valve shall not exceed the limit specified for the area.
+
```datasheet
label: Maximum Predicted Sound Pressure Level
…3 unchanged lines
min: 75
max: 110
− setpoints: [80, 85, 90, 95, 100, 105, 110]
+ setpoints: [75, 80, 85, 90, 95, 100, 105, 110]
default: 85
```
−### Predicted sound pressure level at 1 m from the valve shall not exceed the limit specified for the area.
−
### Where predicted noise exceeds the limit, low-noise trim, downstream diffusers or resistance plates, heavier-wall downstream pipe, or path attenuation shall be provided.
…4 unchanged lines
## Trim Materials {toc}
−### Trim materials shall be selected for the service: erosion, corrosion, temperature, and any abrasive solids. {note}
+### Trim materials shall be selected for the service: erosion, corrosion, temperature, and any abrasive solids.
```datasheet
…53 unchanged lines
### Class IV (metal seat) is the standard for most metal-seated modulating valves; Class V is for critical metal-seat shutoff under high differential; Class VI (bubble-tight, soft seat) is for applications requiring near-zero leakage. {note}
+### The seat leakage class shall be specified per ANSI/FCI 70-2, matched to the shutoff tightness required by the service.
+
```datasheet
label: Seat Leakage Class (ANSI/FCI 70-2)
…15 unchanged lines
## Actuator Type {toc}
−### The actuator shall be sized and selected to position the valve against the maximum dynamic and seating forces at the available supply pressure or motor rating, with margin. {note}
−### Pneumatic spring-diaphragm actuators provide inherent fail-safe action from the spring, smooth modulation, and are the default for modulating service where instrument air is available. {note}
−### Pneumatic piston actuators provide higher thrust and faster stroking for large valves and high differential pressure, and are double-acting (requiring a separate fail-safe means) or spring-return. {note}
−### Electric actuators are used where instrument air is unavailable or undesirable, and are required for most water/wastewater MOVs and for remote sites. {note}
+### The actuator shall be sized and selected to position the valve against the maximum dynamic and seating forces at the available supply pressure or motor rating, with margin.
```datasheet
…8 unchanged lines
default: "Pneumatic spring-diaphragm (modulating, fail-safe spring)"
```
+### Pneumatic spring-diaphragm actuators provide inherent fail-safe action from the spring, smooth modulation, and are the default for modulating service where instrument air is available. {note}
+### Pneumatic piston actuators provide higher thrust and faster stroking for large valves and high differential pressure, and are double-acting (requiring a separate fail-safe means) or spring-return. {note}
+### Electric actuators are used where instrument air is unavailable or undesirable, and are required for most water/wastewater MOVs and for remote sites. {note}
## Actuator Sizing {toc}
−### The actuator output (thrust for sliding-stem, torque for rotary) shall equal or exceed the maximum required seating and dynamic force, including the unbalance force at maximum differential pressure, the packing friction, and the seat load, with a minimum 25% margin at the minimum available air supply pressure. {note}
+### The actuator output (thrust for sliding-stem, torque for rotary) shall equal or exceed the maximum required seating and dynamic force, including the unbalance force at maximum differential pressure, the packing friction, and the seat load, with a minimum 25% margin at the minimum available air supply pressure.
```datasheet
…7 unchanged lines
```
−### Actuator output shall be verified against the valve's published maximum shutoff differential pressure rating; an undersized actuator cannot close against the process and stalls. {note}
+### Actuator output shall be verified against the valve's published maximum shutoff differential pressure rating; an undersized actuator cannot close against the process and stalls.
### The minimum guaranteed instrument-air supply pressure shall be used as the sizing basis, not the nominal header pressure.
## Bench Set (Pneumatic) {toc}
−### The pneumatic actuator bench set shall be specified to preload the spring so the actuator overcomes the seat load and unbalance force and delivers full travel within the diaphragm pressure range. {note}
+### The pneumatic actuator bench set shall be specified to preload the spring so the actuator overcomes the seat load and unbalance force and delivers full travel within the diaphragm pressure range.
```datasheet
…11 unchanged lines
## Fail-Safe Action {toc}
−### The fail-safe action on loss of signal, loss of air, or loss of power shall be specified for each valve based on the process safe state. {note}
+### The fail-safe action on loss of signal, loss of air, or loss of power shall be specified for each valve based on the process safe state.
```datasheet
…55 unchanged lines
## Position Feedback and Controls {toc}
−### The electric actuator shall provide position feedback (open, closed, and intermediate position) to the supervisory system per [[sync/scada-and-hmi-systems]]. {note}
+### The electric actuator shall provide position feedback (open, closed, and intermediate position) to the supervisory system per [[sync/scada-and-hmi-systems]].
```datasheet
…20 unchanged lines
## Valve Positioner {toc}
−### Each modulating control valve shall be furnished with a valve positioner that compares the demand signal to the measured stem or shaft position and adjusts the actuator until the position matches the demand. {note}
+### Each modulating control valve shall be furnished with a valve positioner that compares the demand signal to the measured stem or shaft position and adjusts the actuator until the position matches the demand.
### A positioner overcomes packing friction, actuator hysteresis, and dynamic load to deliver accurate, repeatable positioning, and is required on essentially all modulating valves. {note}
+### The positioner type shall be specified, matched to the control signal and diagnostic requirements of the loop it serves.
+
```datasheet
label: Positioner Type
…11 unchanged lines
## Positioner Diagnostics {toc}
−### Digital positioners shall capture and store diagnostic information for predictive maintenance, including valve signature, friction trend, travel histogram, cycle count, and response signatures. {note}
−### The positioner shall report device health using a NAMUR NE 107 status classification (failure, function check, out of specification, maintenance required) to the supervisory system. {note}
+### Digital positioners shall capture and store diagnostic information for predictive maintenance, including valve signature, friction trend, travel histogram, cycle count, and response signatures.
+### The positioner shall report device health using a NAMUR NE 107 status classification (failure, function check, out of specification, maintenance required) to the supervisory system.
```datasheet
…13 unchanged lines
## Mounted Accessories {toc}
−### The valve assembly accessories shall be selected for the duty and mounted and tubed at the factory as part of the assembly. {note}
+### The valve assembly accessories shall be selected for the duty and mounted and tubed at the factory as part of the assembly.
```datasheet
…99 unchanged lines
## Loop Checkout and Stroke Test {toc}
−### After installation, each valve shall be loop-checked and stroke-tested under [[sync/control-systems-integration]], verifying that the demand from the controller produces the correct travel and direction, that the position feedback to [[sync/scada-and-hmi-systems]] agrees with the actual position, and that the fail-safe action occurs on loss of signal, air, or power. {note}
+### After installation, each valve shall be loop-checked and stroke-tested under [[sync/control-systems-integration]], verifying that the demand from the controller produces the correct travel and direction, that the position feedback to [[sync/scada-and-hmi-systems]] agrees with the actual position, and that the fail-safe action occurs on loss of signal, air, or power.
```datasheet
…17 unchanged lines
## Coordination with the Loop {toc}
−### Loop tuning is performed under [[sync/control-systems-integration]] after the valve is commissioned; the valve assembly shall be left in a condition (correct characterization, minimal deadband, verified travel) that allows the loop to be tuned. {note}
+### Loop tuning is performed under [[sync/control-systems-integration]] after the valve is commissioned; the valve assembly shall be left in a condition (correct characterization, minimal deadband, verified travel) that allows the loop to be tuned.
−### A valve with excessive packing friction, incorrect characterization, or an undersized actuator cannot be tuned out at the controller and shall be corrected at the valve. {note}
+### A valve with excessive packing friction, incorrect characterization, or an undersized actuator cannot be tuned out at the controller and shall be corrected at the valve.
# Delivery, Storage, and Handling {toc}
…53 unchanged lines
### The spare-parts list with manufacturer part numbers shall be included in the closeout documentation.