VRG Controls VPC BV Series - Page 8

VRG CONTROLS LLC. 8 of 60 JUNE 2021
VPC “BV” SERIES VALVE PILOT CONTROLLERS
INSTRUCTION MANUAL
VPC “BV” SERIES VALVE PILOT CONTROLLERS
INSTRUCTION MANUAL
VRG Controls LLC. 8 of 54 APRIL 21, 2019
Variable Descripon Unit
Qc Crical Flow Across Inlet Orice sc
P1 Supply Pressure psig
Cv Flow Factor --
G Specic Gravity of Gas --
T Gas Temperature *F
TABLE 4.0 CRITICAL FLOW EQUATION
Qc=312.9 X (P
1+14.7) X Cv X
1
G X (T + 460)
Where:
TABLE 5.0 FLOW COEFFICIENT TABLE (CV)
Adjustable Orice Flow Coecients
Installed Orice 0 1 2 3 4 5 6 7
Standard 0.006 0.009 0.018 0.044 0.069 0.096 0.111 0.126
Medium (M) 0.042 0.045 0.062 0.089 0.134 0.172 0.211 0.249
Large (L) 0.042 0.063 0.172 0.328 0.461 0.578 0.634 0.675
Adjustable Orice Seng
Notes:
1. Equaon above may be ulized to determine supply regulator consumpon requirements and
steady state bleed rates for control valves operated with a VPC BV Valve Pilot Controller.
2. When applicaons do not ulize Adjustable Orice, then the VPC internal Balanced Valve
becomes the liming factor to determine ow rates and resultant stroking mes. VPC Internal
Balanced Valve Cv=1.45.
Variable Descripon Unit
t Stroke Time Sec.
H Actuator Cylinder Stroke Length in.
D Actuator Cylinder Diameter in.
Cv Liming Flow Coecient --
G Gas Specic Gravity Typ. 0.6 Natural Gas
T Gas Temperature *F
TABLE 6.0 ESTIMATED TRAVEL TIME
Where:
t=0.148 X
G
T + 460
H X D
Cv
2
X