The **Hydraulic Calculator** is used to quickly determine the flow characteristics in a pipe (i.e., its velocity and headloss) given its diameter, length, roughness, and a water flow rate.

To open the **Hydraulic Calculator**, go to the **Model Explorer**, click **Command Center** tab on the bottom, navigate to the **Tools group**, and click **Hydraulic Calculator**.

To run the calculator, specify the pipe variables and then select one of the headloss equations (**Hazen-Williams**, **Darcy-Weisbach**, or **Chezy-Manning**). The results are automatically generated.

**Options**

**Flow**-^{3}/h), or cubic meters per day (m^{3}/d).**Dec. Places**- Choose a decimal place for your flow unit (e.g., choose two places: .02).

**Data**

**Diameter**- The inner diameter of the pipe.**Length**-**Roughness**- The roughness of the pipe, which has different interpretation depending on the headloss equation selected (e.g., the roughness is the diameter of the equivalent sand-grain pipe wall material in mm for the Darcy-Weisbach equation).**Flow**- The water flow rate in the pipe.**Hazen-Williams**- Click on the**Hazen-Williams**button to compute the results for Velocity, Total Headloss, and Unit Headloss.**Darcy-Weisbach**- Click on the**Darcy-Weisback**button to compute the results for Velocity, Total Headloss, and Unit Headloss.

**Chezy-Manning**- Click on the**Chezy-Manning**button to compute the results for Velocity, Total Headloss, and Unit Headloss.

**Results**

**Velocity**- The average cross-sectional water velocity in the pipe.**Total Headloss**- The total drop in hydraulic head between the beginning and the end of the pipe.**Headloss/1000**- The slope of the hydraulic grade line within the pipe, expressed as the headloss per 1000 units of length.