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  1. jack880

    Simple gravity question

    To all the people that have replied in answer to my question, thank you very much. My original question was asking about how to carry out the calculation relating the water depth in the tank, and the speed of flow through the pipe (assuming I can calculate a system curve for the pipe). Our...
  2. jack880

    Simple gravity question

    I wasn't asking you to size it for me, I was aking about how to work it out for myself so I can size it based on the secret flow rate that only I know. The picture was merely a simplified diagram to illustrate my question. It wasn't a "new guy"'s engineering drawing. I am far from a new guy...
  3. jack880

    Simple gravity question

    Thanks for the replies. I take it neither of you know the answer to my question then? David, I didn't fully explain the exact scenario this "new-guy" line will be operating in as it wasn't relevant to my question. I am aware that water can freeze, thank you. Although I am fascinated by how...
  4. jack880

    Simple gravity question

    Hi. I have a water tower,and i need to install a valved pipe as shown in the sketch to allow me to take samples of the water. How can I size the pipe to get the flow I need from gravity? Is it as simple as plotting the system curve for the outlet pipe and the flow will be whatever flow...
  5. jack880

    Control valve - flow and pressure

    Ah ok, i see your point. It's clean water from a service reservoir but not sure what they're testing the sample for - should have only very fine solids in if any I guess. Still, I'll raise the point. Thanks again.
  6. jack880

    Control valve - flow and pressure

    Hi, thanks for the reply. Are you saying that to minimise headloss? I don't care about headloss, I have way too much head anyway. If I used a T instead of a Y wouldn't that just mean my orifice plate would have a slightly bigger hole? Thanks again
  7. jack880

    Control valve - flow and pressure

    Hi, thanks for the reply. I was thinking of putting an orifice plate in the short diversion line to equal the headloss in the much longer other line, so then the tap on the diversion line was opened the flow would be equal on these 2 lines. As you say, if they then increased the headloss...
  8. jack880

    Control valve - flow and pressure

    I've been thinking a bit more and think that the client's requirement of 3-5m pressure at the free discharge tap is ambiguous. If they want the ability to stop the flow with 3-5m back pressure, I'd need a pressure control valve to stop the flow when a downstream pressure of 3-5m is reached...
  9. jack880

    Control valve - flow and pressure

    Just noticed a mistake on the sketch - in the scenario with the take-off valve open, the flow going straight up will be 0.4 l/s minus the flow down the take-off branch, i.e. the total flow from the pump will remain at 0.4 l/s
  10. jack880

    Control valve - flow and pressure

    Hi, thanks a lot for the reply. I think it's my fundamental understanding of flow and pressure that's probably lacking. Please see the attached sketch. When the valve is closed, all the flow from the pump goes round a recirculation system. I want to be able to open a valve (close to the pump...
  11. jack880

    Control valve - flow and pressure

    Hi. I have a flow from a pump, and soon after the pump discharge want to be able to take off half the flow at times, and regulate the pressure. Is this possible with an isolation valve and single control valve as shown in the attached diagram? Thanks in advance
  12. jack880

    Suction lift

    Guys, thanks loads for your replies, this is an incredibly useful forum! I appreciate the issues with priming the pump and air etc - which brings me on to my next question. If the foot valve leaks a bit when the pump isn't running and air gets into the pipe and collects at the top, firstly is...
  13. jack880

    Suction lift

    Hi Johnny. Thanks very much for the reply. Presumably though there is a limit? For example, what would happen if the hump was 100m high? What determines whether or not the water can make it up the vertical bit at all, regardless of the head being recovered on the way down?
  14. jack880

    Suction lift

    Hi. I'm designing a system using a Grundfos JP5 suction lift pump. It can be used to lift up to about 5. The suction pipe has to rise out of the reservoir and fall back down to the pump as shown in the sketch. I know that the lift the pumps needs to deal with is 2m + pipe friction losses...
  15. jack880

    Help with system curve/outlet pressure

    Hi, thanks very much for the reply. Yeah, I was planning to do as you suggest and use a valve to restrict the flow. What's been confusing me is as the pumps are fixed speed centrifugal pumps, is it impossible to have any residual pressure at the outlet of the system as this would just have the...
  16. jack880

    Help with system curve/outlet pressure

    Hi I have a fixed speed pump, and want to design a discharge pipe system such that the outlet pressure at the end of the pipe is 0.4 bar at 0.5 m3/hr. If the system curve and the pump curve intersected at 0.5 m3/hr, there would be no pressure left at the end of the pipe - is that right? Do I...
  17. jack880

    Custom properties in BOM

    Thanks for the help guys, think I've figured it out. You need to link the dimension to a name, then create a custom property and set it equal to that name, then insert a new column into the BOM and link it to the custom property....
  18. jack880

    Custom properties in BOM

    Hi. I've got some parts which are basically just extrusions. I've used a dimension to define the length of the extrusion. When I create a BOM on a drawing, I want to be able to insert another column that displays the length of the part (i.e. the value of the dimension I used for the...
  19. jack880

    Screen captures for reports etc

    Windows 7 has a built in feature called Snipping Tool which is specifically made for capturing screen prints or parts of the screen. Its really good.

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