Cv rating shown below are for regular Port Ball Valves, which may be used in formulae to size valves to any piping system.

Please note that the chart enclosed pertains only to water at ambient temperature.

Pressure drop for Full Port Ball Valves is same as for equal length of standard pipe of same size.

Following formulas may be used to obtain accurate data for any other media.

Cv is the number of gallons per minutes of water which will pass through a given flow restriction with pressure drop of 1 psi.

Flow Characteristics Regular Valves
Valve Size      Cv
6 - 15 MM      2.2
     20 MM      3.3
     25 MM      9.5
     30 MM    13.0
     40 MM    22.0
     50 MM    31.0
     65 MM    68.0
     80 MM    95.0
   100 MM   169.0
   150 MM   314.0
   200 MM   518.0
   250 MM   927.0
   200 MM 1631.0
   350 MM 3004.0
   400 MM 4091.0

 

Liquid Flow Calculation Gas Flow Calculation
Where
Q          = flow in Cubic Mtrs./Hr.
Delta p = pressure drop Bar
Sp Gr    = specific gravity at flowing temperature
Cv        = Valve Flow Co-efficient

Where
Q          = flow in Cubic Mtrs./Hr.
Delta p = pressure drop Bar
P1        = Inlet pressure Bar (Absolute)
P2        = outlet pressure Bar (Absolute)
Sp Gr   = specific gravity (based on air = 1.0)
T          = C + 273

Note : Water at Ambient Temperature.
To convert U.S. Gallons into Imp. Gallons multiply by 0.93



Ball valves Pressure - Temperature Characteristics


Variation of max. non shock pressure w.r.t service temperature.


Note: Values for regular port valves. For full port consider next smaller size.
  Seat Symbol Nominal Valve Size Seat Symbol Nominal Valve Size

A

8 to 25 RP D 200 & 150 RP
B 32 to 80 RP E 300 RP
C 100 & 150 RP  
PTFE seats
  Seat Symbol Nominal Valve Size Seat Symbol Nominal Valve Size

A

8 to 50 D 200 to 150
B 65 to 100 E -
C 150
CFT seats


Note: Values for regular port valves. For full port consider next smaller size.
 

  Seat Symbol Nominal Valve Size Seat Symbol Nominal Valve Size

A

8 to 25 RP D 200 & 250 RP
B 32 to 80 RP E 300 RP
C 100 & 150 RP
25% GFT seats