This module is used to compute the magnitude of the pressure pulse generated due to the closing of a valve in a flow line.

This module calculates the magnitude of the pressure pulse generated due to the closing of a valve in a flow line. The pressure pulse due to rapid as well as slow closing of the valve is computed. The pressure pulse due to rapid closing of a valve is computed using equation (1):

(1)

where DP is magnitude of pressure pulse, r is the fluid density, DV is the change in velocity due to the valve closing, and a is the effective speed of sound.

(2)

where K is the fluid bulk modulus, E is Young’s modulus of the pipe, e is the pipe thickness and D is the pipe diameter.

For slow closing of the valve the pressure pulse is reduced by the ratio of the time taken for the pressure pulse to propagate to the time taken to close the valve. The pressure pulse propagation time t is computed using equation (3)

(3)

where L is length of the pipe.

The inputs for this module are depicted in Figure 1. The inputs consist of pipe geometric dimensions, fluid flow properties, material properties of pipe and flow conditions and time taken to close the pipe.

Figure 1: Inputs for Water Hammer module.

The results are displayed using standard ETBX output window shown in Figure 2. The outputs classification of valve closing speed, magnitude of pressure pulse, speed of pulse propagation.

Figure 2: ETBX Water Hammer module outputs.