Basic Operation and Function of Industrial Regulators

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Basic Operation and Function of Industrial
Regulators
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Regulator Advantages

• Regulators do not require an external power
  source, resulting in less down time.
• Regulators do not require an external packing
  gland resulting in a lower chance of leakage.
• Ease of maintenance.
• Lower installation costs.
• Instantaneous reaction.
• Efficient and durable.
• Self-contained.
• (They do not require external piping.)

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Applying Regulators
KEY CRV Control Valve POR Pilot
Operated Regulator REG Self-contained
Regulator FTC REG Flow-to-close Regulator
FTO REG Flow-to-open Regulator
CRV WP Control Valve w/positioner
CRV WOP Control Valve w/out
positioner
FACTORS CONSIDERED BEST NEXT LAST Line Size
Cost Thru 1-1/2 REG POR CRV 2 thru
3 POR REG CRV 4 and Up CRV POR REG Cost/CV
Thru 1-1/2 POR REG CRV 2 and
Up CRV POR REG Capacity CRV POR REG Outlet
Pressure Level Capability CRV REG POR Output
Pressure Level Maintenance of Set
Point CRV POR REG Rangeability FTO
REG CRV/POR FTC REG Requirements for External
Power (Air or Electricity) REG/POR CRV Stabili
ty CRV REG POR Speed of Response REG POR CRV
WOP CRV WP Ability to Adapt to System
Dynamics CRV POR REG Fail-Safe
Action CRV POR/REG Adaptability (Add
accessories, modify action) CRV REG PRO Remote
Set Point Capability CRV Regulator, Dome
Loaded POR/REG Maintenance Cost/Spare
Parts REG POR CRV
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PRESSURE REDUCING REGULATOR A device that
controls and responds to changes in its outlet
pressure.
Frs
BACK PRESSURE REGULATOR A device that controls
and responds to changes in its inlet pressure.
DIFFERENTIAL PRESSURE REGULATOR A device that
maintains a constant differential pressure
between a reference pressure and the pressure of
the controlled fluid.
Fps
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EXTERNAL PILOTED REGULATOR A piston or diaphragm
actuated regulator controlled by a separate
external pilot mechanism.
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PRESSURE LOADED REGULATOR A regulator using a
fixed volume and pressure of compressible fluid
as a spring and set point reference to accomplish
pressure reduction or back pressure regulation.
sometimes called a Dome Loaded Regulator.
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FTO vs. FTC
FTOFLOW TO OPEN
FTCFLOW TO CLOSE
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REDUCING REGULATORS
Force-Balance Principle
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FTO REDUCING REGULATOR
Inlet Pressure Tends to Push the Plug Open
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FTO REDUCING REGULATO with BALANCED TRIM
Inlet pressure tends to PUSH the plug open and
closed at the same time, causing a
balanced effect.
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DIFFERENTIAL REDUCING REGULATOR
Loading Connection
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FTO PRESSURE LOADED REDUCING REGULATOR with
BALANCED TRIM
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BACK PRESSURE / RELIEF REGULATOR
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BP REGULATOR with UNBALANCED TRIM TOP/CAGE GUIDED
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PRESSURE LOADED BP REGULATOR with UNBALANCED TRIM
TOP/CAGE GUIDED
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DIFFERENTIAL BACK PRESSURE RELIEF REGULATOR
Loading Connection
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PILOT-OPERATED REDUCING REGULATOR
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Droop
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To Minimize Droop on Reducing Regulator and
Build on Back Pressure Regulators

• For a Reducing Regulator when flow demand
  increases the outlet pressure falls away or
  droops from set point.
• For a back pressure regulator when the flow
  demand increases the inlet pressure
• increases or builds above set point.
• Use a larger body size with higher Cv Capacity.
• Use a composition diaphragm material.
• Use full port trim instead of reduced port trim.
• Use the lightest spring possible on pressure
  reducing and heaviest on back pressure.
• Use dome loaded technology.

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Increasing Regulator Sensitivity

• Use a composition diaphragm instead of metal
• Use a lighter range spring
• Use a balanced trim design

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Composition vs. Metal Diaphragms

• COMPOSITION
• More sensitive.
• Increased capacity
• Increased efficiency.
• Recommended when compatible with fluids.
• Same price as metal.

• METAL
• Less sensitive.
• Reduces capacity.
• Recommended for high temperatures.
• Recommended when composition is not compatible
  with fluid.

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Composition vs. Metal Seats

• COMPOSITION
• Tight Shut-off
• No Seat Leakage
• Extended Seat Life
• Recommended when compatible with fluids.

• METAL
• Does not allow tight shut-off.
• Some seat leakage will occur.
• Recommended for high temperature applications.
• Recommended when composition is not compatible.
• Less expensive than composition seats.

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Sizing a Regulator

• Rule 1 Flow rate and set point are integral.
• Set point varies with flow.
• The amount of variation set point with a given
  change in flow is called
• Proportional Band
• Droop
• Offset
• Buildup

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Rule 2 The use of composition seats and
diaphragms will provide
Maximum Flow - Minimum Droop - Minimum Seat
Leakage Proportional Band Droop
Build Offset
Accumulation
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Regulator Sizing Continued. . .

• Rule 3 PRV and BPR DO NOT fail in the normal
  desired mode.

Rule 4 Regulators are best when used in systems
where flow changes are minor.
Rule 5 DO NOT rely on a regulator as a shut off
device.
Rule 6 Never hydro-statically test a regulator.
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Application and Selection Requirements

• What is the service fluid?
• Inlet Pressure (P1)
• Outlet Pressure (P2)
• Flow Rate or Pipe Size
• Temperature

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Technical Bulletins

• Features
• Standard/General specifications.
• Principal of operation.
• Technical specifications
• Design pressure/temperature
• Maximum allowable pressure drops.
• Trim combinations/Temp ranges.
• Capacity Tables
• Dimensions Weights

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