MIKE+ | Pressure relief valves in hydraulic transient simulations

Description

A Pressure Relief Valve protects against excessive pressure in pump stations, distribution systems, and transmission mains by opening when the inlet pressure exceeds a preset value and discharges high pressure water to waste pump suction or a zone of lower pressure.

How to set up

With MIKE+ 2026 you can simulate pressure relief valves within hydraulic transient analyses. This enhancement enables accurate modelling of surge protection behavior by representing valves that open automatically when set-point pressures are exceeded. To define a pressure relief valve, enter the valve using TCV (Throttle Control Valve) Editor and define the valve set-point pressure “Pressure override limit” and the valve “Full stroke time”, time interval within which the actual valve can move from fully open to close position.  See Fig. 1.

Fig. 1 – Valve Editor in MIKE+ 2026 
 

Note, that this valve would typically be installed on a pipe connected to the main pipeline on one side and to the wet-well or a drainpipe on another side. The program will be monitoring the pressure in the main pipeline and will command the pressure relief valve to open when the inlet pressure exceeds a preset value and discharge high pressure water to wet-well, waste pump suction or a low-pressure zone. A reservoir with a fixed water level equal to the pipeline elevation would make a good representation of a wet-well, for example.

Results

Two illustrations below can be used to demonstrate how the pressure relief valve works during the hydraulic transient event. 

The first illustration (Fig. 2) shows the pressure history in the main pipeline, upstream of a pressure relief valve that is set to 300m of maximum pressure. When the pressure reaches this set point level, the valve starts to operate and maintains the pressure at the maximum pressure of 300m. 

Fig. 2 – Pressure time history upstream of a pressure relief valve during the transient event, MIKE+ 2026

The second illustration (Fig. 3) shows the pressure relief valve operation during the transient event. When the valve opens, the water is discharged from the pipeline (into a wet well, in this case) and that helps to relief the high pressure from the pipeline. The amount of discharged water depends on the pressure relief valve capacity.