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Recent content by sow

  1. sow

    Shaft Vibration

    My understanding of modes of vibration / failure of drive shafts is as follows 1) Torsional 2) Lateral (with/ without rotation) 3) Whirl (of shaft, not bearings) However there seems to be a lot of confusion about what is whirl and what is lateral vibrations, some sources say they are the same...
  2. sow

    Brackish Sewage and Stainless Selection

    metengr As I said at the start of the query, I was advised by other users of the steel forum to post here. Not sure of the purpose of your post above. Regards sow
  3. sow

    Brackish Sewage and Stainless Selection

    Posted on the stainless forum, was advised to post it here... We have the following application: 1) Various large diameter valves. 2) Various large diameter pipes / manifolds. The fluid in question is sewage with around 30% seawater.The temperature is 20 - 30 degree C (25 average).The...
  4. sow

    Brackish Sewage Stainless Selection

    We have the following application: 1) Various large diameter valves. 2) Various large diameter pipes / manifolds. The fluid in question is sewage with around 30% seawater. The temperature is 20 - 30 degree C (25 average). The chloride content is 6500 -9500 (average is 8300). We are...
  5. sow

    Australian hazardous area standard classification of diesel storage

    Its covered in the EN regs by the nature of the gas -Ive done zoning before a good while ago and Im pretty sure it specifically covers stuff like diesel, no justification is needed, it is or it isnt.
  6. sow

    Wastewater Valve Clogging

    Exercise the valves once in a while - if they are actuated do it in auto? Do they have flushing points? Gate valves - these are used a lot of solids applications (wedge for sewage, knife for slurry). I would imagine you could trial one from stores. I’ve used RedValve type pinch valves on...
  7. sow

    How can I deal with a harrassing boss

    As somebody who manages other engineers, I can only say that some grads are pretty awful at taking on board suggestions for improvement, and you need to understand that you are asking him to take responsibilty for your work, he is there for a reason and therefore you have to produce work to his...
  8. sow

    Scum Management

    Ive seen plenty of works that pump the scum to the sludge tanks for mixing prior to thickening /dewatering or just straight to dewatering. Ask the suppliers of your dewatering equipment what they think. Problem is that scum can take a lot of water to move and / or unblocking of pumps - but it...
  9. sow

    Flow Away in Force Main Calculations

    You will get some presure back, but bear in mind that the more of a hump you have the more potential for -ve pressure you have + you need to ensure the "gravity" section is primed. You need to draw the hydraulic profile and the pipe profile to make any sense of it.
  10. sow

    I am an engineer am I commiting career suicide?

    I think that doing CAD for a while is an advantage for an engineer. It helps with practical design and helps to make you a more rounded engineer. I know a lot of CAD techs who earn more than engineers. However I would think about how long I could do this before I was pigeonholed. What would...
  11. sow

    Where to go next?

    MJ, My opinion, for what its worth... If you see your career in engineering management (within say 5-10 years) then perhaps you should do the management course? If you see your role as being technical, for at least the next 5-10 years then you should consider the technical course. If so I...
  12. sow

    Hydropower from water mains..

    I don’t think the idea is totally out of the question. Although fundamentally different I have seen these on raw water systems from reservoirs where the head is otherwise throttled to control the flow. If the system is at the start of a long high pressure main then you may step down the...
  13. sow

    Motor Overload

    the flow discharges into an empty main for 10 seconds at start up- the pumps are out on the curve and at full speed for this time and the power curve is rising. The question was, would a temporary overload in power on the motor equate to a failure of the motor (by torque / thermal or other...
  14. sow

    Motor Overload

    Waross - the pumps start up to full speed ok. Im not concerned about the increased current at this point, as we have soft starts to start the pumps. The issue is that the motor is overloaded for a "normal" operation after the pumps are up to full speed (and voltage) for around 10 seconds until...
  15. sow

    Motor Overload

    Thanks for the replies - The motor would be in this state for around 10 seconds every time the motor starts. Could the overload result in 1) an overtorque or increased mechanical stress on the rotor bars. 2) thermal stresses on the rotor bars. 3) any other modes of failure in the rotor bars...
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