Click Auxiliary Calculator  from the InfoSurge toolbar to choose an option from the following options in the drop-down menu.

Wave Speed - This option will help you determine the propagation speed for pressure waves in your pipes. Note that the stiffer the material used and the more the pipe is restrained it causes the  wave propagation speeds to be higher. Using the correct speeds is essential for accurate calculation of the magnitude of pressure surges in the system.


Pipe Material

Pipe Properties

Pipe Restrainment



Resistance - This option will help you determine how much the element resists the flow of fluid through the element. The term is defined as head change divided by the flow squared across an element. The Flow Resistance Calculator can be used to calculate the resistance for a variety of situations. 

Calculate Resistance from


Pump Inertia - This option will help you determine the sum of the pump inertia and the motor inertia. The Pump Inertia Calculator calculates the pump and motor inertia based on the rated conditions using curves fit to a large quantity of data.

Pump Inertia

Pump File Selection - This option will help you determine the head and torque as a function of flow and speed. The Pump File Selector is a utility to assist you in selecting the appropriate Pump File for your simulation (see above screenshot).

Pump File Selection

Edit User Pump File - This option will help you customize an intermediate pump file based on the pump's specific speed. The date in the intermediate pump file is interpolated from the two pump files chosen by you.

Select Pump Files

User Pump File


Select between English and SI units:

Pump File Characteristics - This option will help you to determine operating conditions for pumps described by a pump file based on the rated conditions and the Flow and Speed at which the pump is operating.

Pump Data

Head-Torque Characteristics


Select between English and SI units:

Valve Stroking - This option will allow you to determine the optimum 2-stage closure for a valve in a single pipeline. Based on the properties of the pipeline and initial conditions, it calculates the optimal set of closing time and area ratio for the first stage and the corresponding velocity and head. Note that the valve stroking calculator is valid for single uniform pipeline only but it also provides a general operational rule for a valve operation to minimize the surge problem.

Input Data

Value Stroking Details


Select either English or SI units:

Value Modulating - This option will allow you to calculate the data needed to use an Active Valve as a Modulating Regulating Valve. For normal applications, static active valves are assumed to maintain their initial settings during the transient analysis. To obtain modulating performance, you need to run the steady-state for both the initial and final conditions. With these hydraulic results, you can enter the head and flow values for both initial and final conditions into this calculator. The tool will then provide the corresponding initial and final valve settings, from which you can derive an appropriate operation change curve for the selected active valve over the specified time.


Initial Steady State Conditions

Final Steady State Conditions

Value Modulation


Select either English or SI units:

Air Slam Pressure - This option will allow you to estimate the surge pressure potential due to air expulsion from an air release/vacuum release valve. It calculates the pressure surge generated by the water column impact following the expulsion of air from an air release/vacuum release valve.  You can provide the required data displayed on the screen and an upper limit for the air pressure just prior to the slam and the tool computes surge pressures for a range of air pressures up to the maximum.




Bladder Precharge - This option will allow you to use the results obtained for a Closed Surge Tank to size a Bladder Tank and determine the required precharge pressure. This Bladder Tank will provide the same results as the Closed Surge Tank. The Initial Volume is input for the closed surge tank and the Maximum Volume is determined by the Volume plot for the surge tank. (Make sure the initial maximum volume has been reached.) The initial air pressure is computed by the initial steady state analysis.


Input Data

Output Data


Select English or SI units:

AV Characteristics Curve Generator - This option will allow you to calculate the minor loss (k-coefficient) for a valve based on an input curve of the Open Area Ratio versus the Stem Position. The Active Valve Characteristics Curve Generator can be used to create a curve that describes the Minor Loss vs. Percent Open characteristics of a typical valve. This curve is used to describe the throttle control valve characteristics in the Curve data field of the Attribute Browser. The Throttle Control Valve is used to model an Active Valve in a surge model. After the new AV Characteristic Curve is generated the Create New Curve button will allow you to automatically move the new curve data into the current model's curve data table.


To generate the Active Valve Characteristics Curve, select the valve type or flow coefficient option:

Pipe Data

Wide Open Data

This section of the dialog box allows the user to calculate the Minor Loss coefficient based on a known Minor Loss, Resistance or Valve Coefficient.


Enter the valve diameter, if required, for the curve data calculation.

Active Valve Curve Data