• Re: orifice in surge tanks

    Hello Inbarasan, I'm a bit unclear on some of what you said, but I'll try my best to address your questions: "...which is the effective shape in orifice?" The surge tank orifice is assumed to be circular, as you must enter a diameter. If the…
  • Hammer Analysis in Raw Water Transmission System

    I'm trying to evaluate the need for surge protection at new well locations in a raw water transmission system. I have a network of 6 wells all pumping to the water treatment plant. I'm new to Water Hammer and surge analysis so I'm just looking for some…
  • Hammer: Surge Tank Initial Level

    When modelling a surge tank it is necessary to dictate the initial level. When the steady state conditions are calculated, this seems to not affect the surge tank initial level, even if it does not match the head at the point on the line where it is installed…
  • Hammer: Turbine Curve in Relation to Quadrant Curve

    Hi I wish to clarify how the Turbine Curve should be sourced for inputting into Hammer in relation to which quadrant curve is being used. I understand the Quadrant curve is defined by the selection of the specific speed. In my case, I am picking a…
  • Hammer - Turbine Specific Speed Operating Point

    Hi When calculating the turbine specific speed to use in Hammer, is it more accurate to use the values for P, H, Q & n at the turbine best efficient point or rated point? The specific speed for these two operating points will differ. Kind regards
  • Hammer - Modelling vertical pipes

    I am modelling a hydro scheme which features a vertical shaft directly at the intake. So lets says the intake is J1 at elevation 100m and drops to J2 at 50m by a 50 m length of pipe before completing a 90 degree bend to horizontal. Whe using the profile…
  • Moment of Inertia Turbine Input - Hammer

    Hi I am trouble shooting a Hammer model of a hydro scheme which is producing unexpected results. I have some confusion around which inertia Hammer uses. For hydro generation applications inertia is usually given as WR2 or GD2, with GD2 being four times…
  • Re: How should i enter data for air valves?

    Hello Cesar, I assume you're referring to Bentley HAMMER V8i. When using an air valve, you must be careful to size it such that air pocket collapse doesn't cause worse pressures than without the valve at all. Animate your profile path in…
  • Control valve response to transient event

    Is there a way to model the response of a control valve to a transient event beyond manually inputting the transient operational pattern? An example would be what happens to a PSV when the transient pressure drops below the pressure set point.
  • Re: Suction pipe full vacuum

    Hello Velibor, Some of our other forum members can probably clarify this behavioir better, but I feel that it is likely 'real'. Without examining your network and results, it's hard to tell for sure, but most likely the pump station has a check…
  • Re: Hammer: Pelton free-surface tailrace surge

    Hi, thanks for your reply. You are correct; I am looking at the pipe carrying the water away. I have attached a basic sketch. I am modelling the pelton as a TCV followed by a D2A so I can have multi-stage valve control. Typically I would only be interested…
  • 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.…
  • Re: Pump Inertia - relationship with pump failure & operational pattern

    I concur with Ben. With the "Shut after time delay" transient pump type, the applied torque instantly drops to zero at the time specified in the "time delay until shutdown" field. The impeller is then subject to deceleration based on the pump inertia…
  • Transient Analysis

    Could anybody explain how could analyse the transient behavior of a pipeline in pump start up operation with partially filled & completely with water using Bently Hammer product?. I am using Bently Hammer V8 XM edition. Thanks, Sumith
  • How to model pump trip and restart?

    In Hammer V8i is there any way to model a pump trip/stop followed by a start? thanks.
  • Re: hydropneumatic tank

    Rasha, I'd recommend reading the below technote, which goes into detail on how a hydropneumatic tank works and what all the attributes mean: Modeling Reference - Hydropneumatic Tanks The latest version of HAMMER (08.11.01.32) includes s Hydropneumatic…
  • Hammer Negative Pressure - Instability at Steady State

    Hello, I am using Hammer V8i. I have a simple layout for a pump station transient model. A pump draws from a wet well, and discharges over a syphon into an effluent conduit. The discharge syphon creates a negative pressure at steady state. My transient…
  • Hammer Pump Transient Properties

    Is there anyway to make a responsible assumption for the pump transient properties if accurate data is not available? I have a distribution system model that I've been asked to do some transient analysis for. The model has detailed pump curves but I don…
  • Modeling Valve closure in Hammer

    Hi, I am modeling a HDPE treated water pumping main to see the effects of a pump trip and a valve closure (at the end). I am planning on using a altitue valve and it is supposed to close when the tank is full and also another motor operated valve to…
  • Re: Cla-Val Control Valves in Water Hammer

    Hello BWhite, I do not have experience with those exact valve models, but I can provide some tips. The settings for a surge valve are indeed adjustable, to allow you to customize the valve to match the characteristics of the actual valve you need…
  • Distribution Sytem Wide Hammer and Transient Analysis of RPZ

    I am attempting to set up a model to demonstrate how a RPZ (Reduced Pressure Principle Backflow Preventer) will respond to Hammer. For those unfamiliar with the operation of an RPZ, I have attached a document which outlines this very well. …
  • Hammer Protection Device (Help)

    Dear; I am new in using water hammer software. and i have a project which consist of 900 mm transmission line with pump station. I modeled the project for pump shut down due to power failure and i viewed the results for upsurge and downsurge reults…
  • Modeling pump startup against a closed valve in HAMMER

    We are trying to model a pump startup scenario in HAMMER (v 8.11.03.17) with the pump starting 10 seconds into the simulation and the discharge valve starting to open up 15 seconds into the simulation. We followed the Tech Note for startup scenario but…
  • Re: How should i enter data for air valves?

    Why do you think the results are not real? I would recommend animating your profile path to see if air pocket collapse is occuring - this phenomenon can indeed cause a very high upsurge. I cannot say for sure if your data was entered correctly…
  • Re: Check Valve

    Cesar, You can still have reverse flow through a pump even if the impeller is not spinning (reverse spin disallowed in the transient tab of the pump definition.) So, it is different from the check valve option, which would actually close the pump…