Installed Gain as a Control Valve Sizing Criteria Jon Monsen, Ph.D., P.E.

Control Valve Characteristics Inherent Installed Inherent Installed FLOW CAPACITY, C V VALVE TRAVEL

FLOW CAPACITY, C V VALVE TRAVEL FLOW METER P2P2 P1P1 PP What you need to remember about the inherent characteristic: 1. It is the relationship between valve opening and flow capacity (C V ) of the valve while the pressure drop is held constant. (No system effects.) 2. It is the characteristic that is published by the manufacturer. Inherent Characteristic

VALVE TRAVEL (PERCENT OF RATED TRAVEL) C V is linear with valve travel Linear FLOW CPACITY, C V What you need to remember about the linear characteristic: 1. Its graph is a straight line. 2. It is only used about 10% of the time. Inherent Characteristic

Equal changes in Valve Position produce equal percentage changes in flow capacity. What you need to remember about the equal percentage characteristic: 1. The shape of the graph 2. It is used about 90% of the time. Inherent Characteristic VALVE TRAVEL (PERCENT OF RATED TRAVEL) FLOW CPACITY, C V Equal Percentage (=%) +10 = 50% = 50% +15 = 50%

Installed Characteristic FLOW VALVE  P Pressure source 50 psig 280’ 1.5” pipe gpm

FLOW VALVE  P FLOW (gpm)10 PIPE LOSS1 VALVE  P 49 Pressure source 50 psig ’ 1.5” pipe gpm Crane Technical Paper 410 (1942) Installed Characteristic

FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm)1020 PIPE LOSS13.5 VALVE  P gpm Crane Technical Paper 410 (1942) Installed Characteristic

FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm) PIPE LOSS VALVE  P gpm Crane Technical Paper 410 (1942)

Installed Characteristic FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm) PIPE LOSS VALVE  P gpm Crane Technical Paper 410 (1942)

Installed Characteristic FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm) PIPE LOSS VALVE  P gpm Crane Technical Paper 410 (1942)

Installed Characteristic FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm) PIPE LOSS VALVE  P gpm Crane Technical Paper 410 (1942)

Installed Characteristic FLOW VALVE  P Pressure source 50 psig ’ 1.5” pipe FLOW (gpm) PIPE LOSS VALVE  P gpm Crane Technical Paper 410 (1942)

Installed Characteristic FLOW VALVE TRAVEL =% VALVE Pressure source 50 psig Rule of Thumb: Lots of pipe, use Equal Percentage valve Approx. Linear installed 280’ 1.5” pipe FLOW VALVE  P

VALVE TRAVEL FLOW VALVE  P Pressure source 50 psig 2.8’ 1.5” pipe Linear inherent  Linear installed 0.28 psi 60 gpm Rule of Thumb: Very little pipe, use Linear valve Installed Characteristic FLOW

Installed Gain Valve Travel, h Gain =  Output /  Input Installed Characteristic and Gain Installed Characteristic Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain  q =  h X Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain % 1/4% Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain  q =  h X Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain % 1/4% 4% Gain =  Output /  Input Gain =  q /  h = SLOPE Installed Characteristic and Gain  q =  h X Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Installed Gain Gain =  Output /  Input Gain = d q / d h = SLOPE Installed Characteristic and Gain Installed Characteristic Valve Travel, h Flow, q

Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  2.0 Gain =  Output /  Input Gain =  q /  h  q =  h X Gain Installed Gain Recommendations Installed Gain q min q max Flow

Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  2.0 Gain =  Output /  Input Gain =  q /  h  q =  h X Gain Installed Gain Recommendations Loop Tuned here Data courtesy of ExperTune, Inc. SP PV Large gain change: Can’t maintain good control with stability throughout flow range. The “un-tunable” loop! Installed Gain q min q max Flow

Installed Gain q min q max Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  2.0 Gain =  Output /  Input Gain =  q /  h  q =  h X Gain Installed Gain Recommendations Flow Loop Tuned here SP PV Data courtesy of ExperTune, Inc. Small gain change: Good control with stability throughout flow range.

Installed Gain q max q min Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  As constant as possible 5.As close to 1.0 as possible Installed Gain Recommendations Flow Gain =  Output /  Input Gain =  q /  h  q =  h X Gain Installed Gain q min q max Flow

CvCv Valve Travel Actual inherent flow characteristic Actual system characteristic Flow, gpm Pressure, psig P1 = 42 P1 = 32 P2 = 10 P2 = P1 = 36 P2 = 11 Min Norm Max Software Graphs Installed Characteristic & Gain q f =766

6” Sch ’ (Equiv. pipe & fittings) 230’ 70  F Water 10 P2P2 P1P1 P FC =% Inherent characteristic Flow gpm P P psig Pipe Loss (up) P 1 psig Pipe Loss (down) P 2 psig  P Flow, gpm Pressure, psig P1 = 42 P1 = 32 P2 = 10 P2 = 12 Sizing Example CvQ G P  

Sizing Example

 85 dBA for 6”  32.8 fps  p <  p T Sizing Example

 80 dBA for 3”  32.8 fps Sizing Example  p <  p T

6” 3” Sizing Example

6” 3” ” 3” q max q min Installed Gain q min q max Installed Gain Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  As constant as possible 5.As close to 1.0 as possible Sizing Example 4”

What is the optimum control valve pressure drop to design into a system to ensure adequate control while avoiding the use of excessive pumping power? Selecting the Right Pump

TC Pump head droops 5 psi from 100 gpm to 600 gpm Pressure gpm 6” Sch 40 70°F Water P2P P 1 (Pump A) 17 hp* P 1 (Pump B) 23 hp* * At normal flow (400 gpm) P1 P P 1 (Pump C) 29 hp* Selecting the Right Pump valve characteristic Inherrent Installed Min. Norm.Max.

PRESSURE DROP = 5 MAX. FLOW Pump power = gpm Selecting the Right Pump

PRESSURE DROP = 5 MAX. FLOW Pump power = gpm

6” Selecting the Right Pump PRESSURE DROP = 5 MAX. FLOW Pump power = gpm

3” Selecting the Right Pump PRESSURE DROP = 20 MAX. FLOW Pump power = gpm

3” Selecting the Right Pump PRESSURE DROP = 35 MAX. FLOW Pump power = gpm

5 psi, 17 hp 20 psi, 23 hp 35 psi, 29 hp q max q min Installed Gain q min q max Installed Gain Within the specified control range: 1.Gain  Gain  Gain (max) / Gain (min)  As constant as possible 5.As close to 1.0 as possible 3” 6” Selecting the Right Pump

20 psi, 23 hp 35 psi, 29 hp 3” Maximum Calculated SPL To avoid cavitation damage UP TO 3” 80dBA 4” TO 6”85 dBA 8” TO 14”90 dBA 16” AND UP95 dBA Selecting the Right Pump

Thank you!