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  1. impeller1

    Best Method to Survey Piping

    Hi All, Firstly let me start off by saying I'm not well versed with all the lingo associated with Surveying, so please forgive me if I use some of the terminology incorrectly. I just wanted to get some input / advice with respect to performing a pipeline survey to monitor movement of the piping...
  2. impeller1

    Vessel Cover Gasket

    Hey Everyone, I have an urgent problem here, basically, I've got a vessel with an operating pressure of 10 bars. The incorrect gasket was used to seal to top cover flange of the vessel (approx 3950mm in diameter). The correct gasket was now specified in terms of material, however, two different...
  3. impeller1

    Weldolet vs Flat Weldolet

    Hey all, I'm fairly new to fabrication and welding, so I wanted to find out if there is a difference between a weldolet and a flat weldolet. I have to specify one for replacement, and according to my Isometric, its specifying a flat weldolet. I did a little digging and saw somewhere that flat...
  4. impeller1

    Vertical Turbine Pump Flow Inlet Velocity

    Hi guys, I have a little problem. I'm trying to determine the inlet flow velocity of fluid to my pump. It's a 4 stage vertical turbine pump and its situated to one end of a well. Water flows into the well via a 24" diameter pipeline at an entrance velocity of approximately 8 ft/sec. Now the...
  5. impeller1

    Butterfly Valve Question

    Good day, Happy New Year to all of you. Young Engineer here, and I have a question about the material of a particular valve. We've got 30" butterfly valves that are underwater (seawater) and are currently in need of replacement. Unfortunately, the valves are obsolete and are not manufactured...
  6. impeller1

    Impeller Trimming

    Good day, We're considering trimming the impellers on our 6 vertical turbine Pumps. Pumps are consuming too much power and we'd like to reduce it by trimming them. I would like to know, is there any particular method / procedure to trimming impellers? The impellers are semi open impellers. Do...
  7. impeller1

    12 stage centrifugal pump

    Good day, I just need confirmation on something. I have a 12 stage horizontal centrifugal pump. I have recorded values of flow, suction pressure, discharge pressure and speed. I'd like to work out the flow and differential head values to the rated speed. I've applied the affinity laws: N1/N2 =...
  8. impeller1

    Motor Horsepower

    Good day, I have a pump and motor configuration. I'm trying to find the equation to calculate the horsepower that the motor is producing. I have the motor current and voltage. it's a 3 phase motor, so I'm assuming I have to use this; P = (3)^1/2 x V x I x cos(power factor) ?? Can someone...
  9. impeller1

    Air Release Valves

    Good day, I'm not too familiar with ARV's however I know the basic principle behind how ARV's work. However, what exactly are the "Air and Vacuum Flow rate" and the "Automatic Air discharge"? I noticed each is plotted on a graph, but what exactly does it represent? Also, in selecting an ARV...
  10. impeller1

    Running off BEP

    Good day Folks, If you have a pump running far off to the right of its BEP. You're head's gonna drop off and your flow should increase right? According to its performance curve. Now, does your fluid velocity increase to the extent that not enough water is being supplied to your mechanical seal...
  11. impeller1

    Power in Parallel Pumping

    Good day All, A question here..I have 6 vertical pumps in parallel. Now, all 6 were fitted with slightly larger impellers. With this upgrade, their BHP's have gone up to around 600 horsepower. From the attached sketch you can see the arrangement. All 6 discharge into a large 42" header which...
  12. impeller1

    Thinking about doing a Master's

    Good day, Well im 24 and graduated with my BSc in Mechanical Engineering in 2008. I've been working since then and now I'm looking at doing a Masters. I'm looking at doing it in Canada but I noticed most of the degrees they offer is an MEng or MSc on Mechanical Engineering. I was thinking to do...
  13. impeller1

    Pumps in Parallel

    Good day, My Boss threw an idea at me which while sounds correct in theory, I'm not sure how accurate it is practically. We have 6 vertical pumps in parallel and there's a discharge gauge on each. We have no individual flowmeters, just a total flow of all 6 pumps from the header. My boss was...
  14. impeller1

    Plotting Performance Points

    Good day, A colleague of mind asked me to help him plot random points on a design curve for a pump. Now I helped with the equations etc, however we can't explain why the majority of the points are far above the curve. Attached you;ll see our results. All data is included and the curve is lower...
  15. impeller1

    Testing a pump dead-headed

    Good day Folks, Im sorry if this is a dumb question, but I have 6 vertical pumps. I'd like to test them to determine where they're operating on their performance curves. However, I do not have the system curves and I'd like to test the pump alone minus the system. These pumps are VFD's so I can...
  16. impeller1

    Calder ERT (Desalination Process)

    Folks, Is anyone familiar with the Calder Energy Recovery Turbine? Specifically, model no. RO-300-100-4? I'm trying to interpret the performance curve for it, however it's not labelled properly and I can't determine what its giving you. All I know is that Flow is on the Y-axis and Pressure on...
  17. impeller1

    Pump Efficiency

    Folks, We have 6 vertical turbine pumps (3 stage) which are rated at delivering 4400 gpm. From commissioning, which was approximately 9 years ago, the pumps delivered around 4300 - 4400 gpm. Fine. Recently, we have seen the performance drop to 3900 - 4000 gpm, around a 10% drop in performance...
  18. impeller1

    Motor Power

    Good day, We're looking at fitting larger impellers on a few pumps onsite. From manufacturer's testing, according to the performance curves, the pump's Brake Horsepower is 350 HP. Currently the pump's brake horsepower is 314 HP and they use 350 HP motors. Can these new impellers be used with...
  19. impeller1

    Suction Lift

    Good day, A pretty baic question here..sometimes the basics get a little confusing :) I have a pump operating on a suction lift. Im trying to find the differential head across the pump, I have a discharge pressure gauge so that would effectively account for all losses and fittings on the...
  20. impeller1

    Pump Curve

    Good day, I am trying to approximate the performance of a pump onsite. When plotting the point on the curve, the Total head the pump is operating at does not correspond to the flow its delivering. The flow its ACTUALLY delivering is around 5,100 gpm, while the flow it's SUPPOSED to deliver...

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