• Sewer main not emptying when it should?

    I´m modeling a sewer system that pumps 6.4 m3/s along 100 m of pipe, up to a 42 m elevation height, as seen on the picture below. The sloping green line represents a vertical riser pipe modeled by setting the elevations to 0 and 34 m, and the user…
  • How to model discharge to atmosphere point

    HI, I'm working on my college project (The project is a plumbing system to drain a 1-m3 tank in the shortest time ). I use the discharge to atmosphere element at the end of the project but I'm really confused with this element's input data like [Flow…
  • Why does changing a junction to Discharge to Atmosphere (D2A) cause the initial conditions to fail and generate greater flow than the demand?

    I am modeling a sewer force main until it reaches it's highest point (third to last node), discharges to atmosphere (second to last node), and then turns to go downhill (last point). When the last two nodes are modeled as junctions, the initial conditions…
  • Model a riser in Hammer CONNECT

    I am doing surge modeling using Hammer Connect. I have a distribution system with demand nodes scattered here and there. At each demand node, there is a water storage tank and a riser delivers water into the tank. The riser is higher than the water level…
  • RE: Negative pressure at junctions (Hammer V8i Select Series 5)

    Since the distance between the two elements is relatively small and the elevation difference is also relatively small, what I would do is a sensitivity analysis. Do the first analysis with the actual distance the discharge to atmosphere will be located…
  • RE: Negative pressure at junctions (Hammer V8i Select Series 5)

    Phanindra, In this situation since the transient wave would not proceed past the air gap in the high point it may be best to end the system there at a discharge to atmosphere element . More information about modeling high points in a transient model…
  • RE: Top fill tank with air gap

    Kathryn, The best option would be to model this as a discharge to atmosphere element set as the type "Orifice". This takes into account unsubmerged discharge points that empty into the top of tanks that are open to the atmosphere. You need to decide…
  • RE: Simple model question

    Matt, For modeling this scenario you'll need to be familiar with how to use the active topology alternative to create a new scenario with a 3" pipe that has a discharge to atmosphere (d2a) element on the end of the pipe. This wiki explains how WaterCAD…
  • RE: How to model downstream service reservoir the right way for surge analysis? (Bentley Hammer V8i)

    Joshua, If there is free discharge from the pipe into "service reservoir B", then I concur with modeling it as a D2A. The "typical flow" would indeed be set to the expected flow into that tank, and the "typical pressure drop" would be set to the corresponding…
  • RE: modeling fire hydrant in hammer checking the network against transient

    The Discharge To Atmosphere element can also be used to simulate transient effects of a hydrant closing too fast, by setting the Discharge Element Type to Valve. An example of this is included in the "Samples" folder within the HAMMER installation folder…
  • RE: Modeling Transmission line priming starting from Empty conditions?

    If you're using Bentley HAMMER for a transient analysis on this system, here are a few related resources: Modeling a case where an empty pipe is filling using Bentley HAMMER Forum Post #1 Forum Post #2
  • Modelling a Pelton

    I am modelling a hydro station with 4 pelton units for pressure rise and mass surge. I have currently modelled these as a discharge to atmosphere element as is recommended in the Hammer knowledge base. However, using a discharge-to-atmosphere element…
  • Re: Top Feed Gravity Dischare Tank

    Hi, I would suggest ending the system at the inlet of the tank using a discharge to atmopshere node element, since the tank itself and downstream elements won't be effected by the valve closure. The Discharge to Atmosphere node can be configured as…
  • Re: Dischage to atmosphera

    The "Pressure Drop (Typical)" and "Flow (Typical)" fields are used to automatically calculate a flow emitter (orifice) coefficient, which will be used during the simulation to calculate outflows. Basically HAMMER uses that coefficient to calculate how…
  • Re: Pipelines with a Free Discharge

    Hello, Since there must be some pressure head at the discharge to atmosphere location, it won't really be a "free" discharge. So, I think you would indeed expect some energy dissipation and wave reflection. With this element, you'll be…
  • Approximating a connection to an existing network

    When using hydrant test data to approximate a connection to an existing water distribution system, should the flowed hydrant be the hydrant on the side of the extension, or the gaged hydrant, or does it not matter? Also, how would elevation difference…
  • Re: Modeling tanks inlets

    Hello, For a steady state or EPS simulation, a top-feed tank is typically modeled by using a PSV on the upstream side. By setting the PSV to the top elevation, the HGL will be forced up to that elevation instead of the tank initial elevation.…