Valves

Various valve types are available for use, depending on operational intent.  

• Gate Valves and Butterfly Valves are typically used for isolating flow in a section.  They are modeled as either fully open (allowing flow through the valve) or fully closed (prohibiting any flow through valve).  

• Check Valves are used to limit flow in the installed section to a single direction.  When flow is in the allowed direction, the check valve is fully open.  When flow reverses and attempts to flow in the prohibited direction, the valve fully closes to prevent any backflow.  

• Globe Valves may be used for isolation, or to manually regulate flow conditions by using defined Flow vs. Pressure-Drop relationships for the valve at specified open percentages.  

• The PRV, or Pressure Reducing Valves, are modeled as globe valves with a controller.  They are used to limit the local downstream pressure to a set value.  

• Hydrants are modeled as isolation valves in a normally-closed position.  A fire load can be attached to a hydrant using a water system load component.

All of these valves share the same basic component properties and dialog structure, as shown below for the Gate Valve.  See General Dialog Details for information on common dialog fields and commands, as only the highlighted fields and commands unique to Valve dialogs are addressed in this topic.  

Z: [___] - this is defined to be the topographic elevation (feet above sea level) for the represented location, i.e. at ground level.  

Condition

• Open - specifies that the valve is in the open position, allowing flow.

• Closed - specifies that the valve is in the closed position, with flow set to zero.
   

Ratings

Max Pressure (psi) - when available, displays the maximum pressure rating for the valve, in pounds per square inch.

Max Velocity (fps) - when available, displays the maximum velocity rating for the valve, in feet per second.

Valve Pressure Drop (or "Friction Factors")

Flow Coefficient (Cv) [__] - specifies the flow - pressure drop relationship for the fully open valve in accordance with the standard definition for US Customary units, i.e. the Cv is the number of US gallons of water the valve will pass with a differential pressure of 1 psi. The pressure drop (dP psi) for a given flow (Q gpm) is determined by the relation:

dP (psi) = Q2 (gpm) / Cv2
 

Scaling Factor - derating factor that allows user to adjust valve performance from published manufacturer's rating (i.e. new condition) to compensate for aging or other adverse field conditions effecting actual flow conditions.
 

Set Monitoring Point

[Select Cmp] - allows user to select (with pointer finger) the component location that defines the control point where the control variable is applicable.  With no control location specified, the input control variable is applied at the control valve itself.  

Controller Serial - displays the serial number of the selected control point component, as applicable.

X,Y -  displays the (x,y) coordinate location of the selected control point component, as applicable.  

PRV Setpoint - when applicable, specifies the maximum pressure (in psi) allowed at the control location.  If the operating pressure at the control location exceeds the maximum, then the valve sets pressure to the specified value.  Lower pressures are permitted and do not result in any valve adjustment.
 

% Open - defines the current valve operating position, as a percentage of fully open.