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How can I model a Vent Pipe in HAMMER?
The Surge Tank element is the correct way of modeling a vent pipe in HAMMER, as it simulates water in a vertical pipe/tank with a free water surface.One thing to keep in mind is that the surge tank element does not support air inflow when it becomes empty. HAMMER assumes that the user will design a tank that will not become empty.If you must model full drainage of the "vent pipe", one possible workaround would be to place an Air Valve node directly adjacent to the Surge Tank. Set the elevation of the air valve to the bottom of the tank and the diameter to the size of the vent pipe. Be sure to reduce the tank's minimum, base and physical elevations such that these are never reached (make them slightly below the true tank bottom.) This way, when the water level in the tank reaches the bottom, the air valve will open up and allow air inflow. Note however that if the tank subsequently refills during your simulation, a surge will occur when the air valve closes (after all the air has been expelled). Therefore it may be best to omit the air valve from the model and accept the limitation of the empty surge tank (which doesn't model air inflow), since the transient response may be similar.