|Pipe 2018 incorporates a number of standard valves. These are called “active valves” within the interface because their open area may be fractional, as opposed to on/off valves which are either fully open or fully closed.
Head loss across a valve is described by either the Flow Coefficient, Cv, or Resistance (head loss/flow2); users can specify Cv or Resistance within the Preferences Menu.
The Active Valve Table shown below gives the open area ratio (open area/fully open area) as a function of ratio of the stem movement to the full movement (S(tem) Ratio). The 0 value is fully closed and 1 is fully open. This table shows, for example, a ball valve where the stem position is half-way open (0.5) and the open area of the valve is 41.88% of the fully-open area. Users can create their own valves.
For Surge analysis, valve closings and openings are modeled by providing the time history of the stem movement. For example, a ball valve can be linearly closed in 4 seconds, which means that the stem movement is linear.
Active Valve Table
|The active valve node can be used to model a check valve and a 2-way resistance using the bypass line feature. For KYPipe applications, a check valve node (an internal node) is also available.|