Surge and water hammer by the method of characteristics: pump trips and starts, valve closures, column separation, fire water priming and surge protection, on the same model as the Liquid mode, and every case of the study in the Scenario Manager.
Pressure waves through the whole network by the method of characteristics, with the wave speed of every pipe worked out from its material and wall.
Sudden power failure, run-down and restart, with the inertia of the pump and its motor, and the check valves closing behind them.
Fast and slow strokes, emergency shutdown valves, deluge valves and control valves, each with its characteristic.
Air vessels, surge tanks, air valves, surge relief valves and rupture discs, sized by running them.
Column separation at vapour pressure, the cavity that opens and the pressure when the columns meet again.
The unbalanced forces on every pipe run through the event, for the pipe stress engineer.
Trips, starts, strokes and set points in time, or driven by a pressure or a level as the plant's own controls do.
The highest and the lowest pressure each node saw, on the sheet and drawn along the line against its rating.
Every closing time, every protection, every pump combination as a case of the same model, run in one go.
A deluge system is dry behind its valve, and a caisson fire pump starts with nothing above it but air. How long until water reaches the last nozzle, and what happens when it gets there, is a transient question. Flowmax fills dry pipes with a front of water, pushes the air ahead of it out through the nozzles and the air valves, and gives the time, the pressures and the forces all the way.
A fire pump started on a dry riser: the riser full to the cellar deck 5.1 s after the start, the water at the top deck air valve after 33.4 s, and how the air valve outlet sets that time.
A deluge valve opening on a dry branch: the pipes fill one after the other, the first nozzles flow 3.6 s after the opening, the last 6.9 s.
Water running into an empty branch is stopped at its end: 33.9 barg at the last nozzles for an instant, and the forces on the riser and the header.
The duty pump tripping and the diesel standby taking over: the header back to pressure 0.7 s after the start, and the force on the pump header.
A surge study is never one run. Set the cases once — here eight on a fire water ring main: the deluge valve closing in 1, 2 and 5 s, a monitor closing, the pump tripping — press Run all, and read every case on one chart and in one table, each result against its limit, the ones over it in red.
The model you solved in the Liquid mode is the one you trip: no second model, no data typed twice.
The transient solver is checked against the closed-form theory of hydraulic transients: see the validation.
A ready model of a 20 km water line: a power failure trips both pumps, the column separates at the summit, then an air vessel, an air valve and a slower valve protect it.
Request a free trial and run your own surge study with Flowmax.
