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Regulator and Control Valve Sizing

By

Hugh Masterson and Jim Mueller

Master Controls

March 13, 2019 2

What is a regulator?

A Regulator is a device that controls the flow of gas from a higher pressure system to a lower pressure system while

attempting to maintain a constant pressure or flow.

HIGHER MAOP LOWER MAOP

Regulator Selection

o Select the correct regulator for the application considering the following:

• Speed of response, i.e., boiler fuel

• Differential pressure

• Turndown = Max flow/min flow

• Noise

• Accuracy

• Self Operated

• Pilot Operated

• Control Valve

Selection Chart

Regulator Orifice or Valve Size (Inches)

Pilot-Operated(Shaded Area)

Self Operated “Farm Tap”

HOUSESERVICE INDUSTRIAL

Self-Operated Rollout Diaphragm

Self Operated Pressure Reducing Regulator

Loading Element

Measuring Element

Restrictive Element

10 psig

10 lbs force

High Pressure

Low Pressure

100psig100psig

Sizing Tips

Factors to Consider

• Filter - pilot supply – always.

• Filter - entire station?

• Overpressure protection?

• Hydrates and/or freezing (Joule-Thompson effect)? Adding a pilot gas heater?

• Throttle plate selection (capacity and type to prevent diaphragm erosion in high pressure cuts).

• Exit and downstream gas velocity. Larger regulators and downstream pipe diameters results in lower velocity.

Sizing Tips

Factors to Consider

• Pipeline turbulence caused by other equipment (elbows, tee’s, valves, etc.) that can affect sense lines.

• Sense lines should be 8 to 10 pipe diameters down stream, 4 diameters upstream of a tee or elbow.

• Diaphragm selection (chemical compatibility, differential pressure rating, temperature, resistance to abrasion).

• Solution versus cost assessment

• Single regulator or monitor regulator set?

Sizing Tips

Noise

• Consider 1-stage vs. 2-stage design to reduce noise levels (2 stage has less noise).

• Use a drilled or stepped drilled hole throttle plate to help reduce noise.

• Increase size to lower theoutlet velocity and reduce noise levels.

• Increase pipe wall thickness to reduce noise levels.

Sizing Tips

Capacity

– Optimal design should not exceed 75% - 80% of maximum capacity (capacity factor of 75% - 80%) .

– Better to oversize than undersize.

– Rangeability (turn down)

» 50:1 – Slotted throttle plate

» 100:1 – Slotted throttle plate

» Greater than 100:1 – Stepped drilled hole throttle plate

Sizing Tips

Design Considerations

o Minimum pressure differential :

See Differential Chart

o Maximum pressure differential :

800 psid (1000 psid for 1”)

Mooney Flowgrid Regulator

Pressure Reducing Application - Standby Monitor

Confidential

Sizing Conditions

o Maximum ∆P ANSI Class, Regulator Specification Maximum control point, % Open Minimum control point, % Open

For Mooney regulators usestepped drilled hole throttleplates for Cg’s less than 4 to 5% of the regulators capacity

o Max Downstream Gas Velocity Above ground ~100 fps Below ground ~200 fps

o Max Valve Exit Velocity 0.3 X Mach ~230 fps

o Control Valve Operating Range Standard Becker; 10 - 93% open

o Max. Cv Condition Max. Flow (Q) Min. Inlet Pressure (P1) Max. Outlet Pressure (P2) Max. Temperature (T)

o Min. Cv Condition Min. Flow (Q) Max. Inlet Pressure (P1) Min. Outlet Pressure (P1) Min. Temperature (T)

o Max. Noise Condition Max. Flow (Q) Max. Inlet Pressure (P1) Min. Outlet Pressure (P2) Max. Temperature (T)

Universal Gas Sizing Equation

11

1

3417

GT

520Q

P

P

CSinPCg

Cg = gas sizing coefficientCv = liquid sizing coefficientC1 = Cg/CvG = gas specific gravity (air = 1.0) P1 = inlet pressure, psiaP2 = outlet pressure, psiaΔP = pressure drop P1 – P2, psiT = flow temperature, °R(460 + °F)

Follow these instructions.Select the ValSpeQ vX.XX link above and save to a location on your hard drive.DO NOT CLICK THE RUN BUTTON FROM THE DOWNLOAD DIALOG. CLICK ONLY THE SAVE BUTTON.RUN ALL INSTALLS BY USING THE RIGHT CLICK “RUN AS ADMINISTRATOR” METHOD

After successful and complete save to the file system…¨ If this edition has never been installed on the pc before, you will get prompted for registration information

belowo If prompted for Product Key, enter 60015410o If prompted for Install key, leave this area blank, and hit nexto Enter all registration informationo If prompted to save registration file to desktop, do so.\o If prompted to e-mail registration in, do so, copy valspeq.support@ge.com on the resulting e-mail

that gets created by the installer.o Hit back button and wait for the install key from me., if you hit finish, you will have to rerun the

installation when you receive the install key.o When you receive the install key, enter the install key code, and hit next, the installation will

continue.¨ Otherwise the install will not prompt and you can proceed normally.

Regulator Sizing Examples

Regulator Sizing Example 1

Max Cv Case Min Cv Case Noise Case

Flow Rate (Q) MSCFH 300 20 300

Upstream Pressure (P1) 150 psig 240 psig 240 psig

Downstream Pressure (P2) 30 psig 30 psig 30 psig

Gas Temperature deg F 60 60 60

85 - 90 dBA Noise Requirement

Flow Rate (Q) 20 – 300 MSCFHUpstream Pressure Range P(1) 150 – 240 PSIGDownstream Pressure P(2) 30Inlet Gas Temp 60 deg F

Regulator Sizing Example 2

Max Cv Case Min Cv Case Noise Case

Flow Rate (Q) MSCFH 30 4 30

Upstream Pressure (P1) 700 psig 850 psig 850 psig

Downstream Pressure (P2) 150 psig 150 psig 150 psig

Gas Temperature deg F 60 60 60

85 - 90 dBA Noise Requirement

Flow Rate (Q) 4 – 30 MSCFHUpstream Pressure Range P(1) 700 – 850 PSIGDownstream Pressure P(2) 150Inlet Gas Temp 60 deg F

Joule-Thomson Effect

When a highly compressed gas is allowed to escape / expand through a small opening, it absorbs a great deal of energy from its surroundings, causing the surrounding temperature to drop. This

is the basis of refrigeration.

As a rule of thumb gas temperatures will drop ~ 7 Degrees F for every 100 psig in pressure drop.

Joule-Thomson Effect

Pilot Gas Heating

Pilot Gas Heating

Control Valve Sizing Examples

Control Valve Sizing Example 1

Max Cv Case Min Cv Case Noise Case

Flow Rate (Q) MMSCFD 300 25 300

Upstream Pressure (P1) 950 psig 1050 psig 1050 psig

Downstream Pressure (P2) 935 psig 935 psig 935 psig

Gas Temperature deg F 60 60 60

85 - 90 dBA Noise Requirement

Flow Rate (Q) 25 – 300 MMSCFDUpstream Pressure Range P(1) 950 – 1050 PSIGDownstream Pressure P(2) 935Inlet Gas Temp 60 deg F

Control Valve Sizing Example 2

Max Cv Case Min Cv Case Noise Case

Flow Rate (Q) MMSCFD 440 50 440

Upstream Pressure (P1) 900 psig 1200 psig 1200 psig

Downstream Pressure (P2) 850 psig 850 psig 850 psig

Gas Temperature deg F 60 60 60

85 - 90 dBA Noise Requirement

Flow Rate (Q) 50 – 440 MMSCFDUpstream Pressure Range P(1) 900 – 1200 PSIGDownstream Pressure P(2) 850Inlet Gas Temp 60 deg F

Filters and Filter/Dryers

Cold Gas Increases the potential for liquid dropout

Joule-Thomson Effect

When a highly compressed gas is allowed to escape / expand through a small opening, it absorbs a great deal of energy from its surroundings, causing the surrounding temperature to drop. This

is the basis of refrigeration.

As a rule of thumb gas temperatures will drop ~ 7 Degrees F for every 100 psig in pressure drop.

Filtering

Vertical Pipeline Heater

Horizontal Pipeline Heater