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  1. jonelv

    Services Piping in Seawater Tunnel at 55m depth

    What fluids are you transferring throught the pipes and what are the internal pressures? For general materials, I have used duplex stainless steels for seawater applications as you get good combination of strength and pitting and crevice corrosion resistance. These are expensive though and...
  2. jonelv

    Friction Losses Claculation

    pivot The maximum flow rate is important to understand. As Artesi says, is the flow continuous throughout the day? Re the friction, for 1% sewage you can assume Newtonian flow. If you use Darcy to calculate then you can factor in the slightly different density / viscosity into the Reynolds...
  3. jonelv

    Sulphuric Acid Tank Vents

    Hello I'm doing a review of some old (30 years plus) acid tanks, containing 96% sulphuric acid. Some are atmospheric tanks, some are designed for 2barg internal pressure. Although I can find no specific references in standards (BS or API) it is my understanding that atmospheric tanks should be...
  4. jonelv

    Pump Hous Intake design

    I may be in a minority from looking at the other posts but what you describe looks to me like a 'trench type' sump arrangement. I have seen these arrangements with multiple vertical pumps work well. The design parameters for such sumps are covered by ANSI/HI. The higher velocities present may...
  5. jonelv

    Process Line Highpoint - column separation?

    Hello I'm looking at a design where I'm pumping from approx ground level (say 0m), over a pipebridge (7m elevation) to a vessel (1m) which is open to the atmosphere. The downhill part of the pipeline is a near vertical drop. My thoughts are to treat the headloss design for the pump duty point...
  6. jonelv

    Parallel Pumps - Pressure / Flow control

    Hydrae Thanks for this. Accepting that the pumps may run at slightly different speeds to achieve balance, do you think I'm therefore likely to get best balance by controlling pumps against current setpoint (ie target amps) rather than speed? Jo
  7. jonelv

    Parallel Pumps - Pressure / Flow control

    Hello Looking at a pumping system comprising 3 VSD centrif pumps discharging into a rising main. Pumps can run either on their own or any 2 in parallel. I want to ensure that in parallel the load is shared and pumps run at same speed. To maintain a dedicated pressure in the main, is it best to...
  8. jonelv

    Ferric Chloride Dosing

    Depends on what you're trying to achieve and process stream flow rate. Assuming you're dosing wastewater to suppress septicity? Last plant I did used variable speed diaphragm pumps to dose 40% w/w FeCL between 300 and 750 l/hr. Jonelv
  9. jonelv

    Air/Vacuum Release Valves?

    Lexwater You and the rep may be at cross purposes. You don't necessarily just put air valves at high points - you may also put them where you have changes in the gradient either upslope or downslope or at regular intervals on long horizontal, ascending or descending sections. Its the pipeline...
  10. jonelv

    Waterworks Sludge Pumping

    Hello, Trying to find data for typical viscosities for thickened waterworks sludges (2-3%d.s.) in order to check pressure drop in pump system. Sludge will be drawn off WRC thickener. WRC TR185 gives useful data for sewage sludge but haven't seen anything for waterworks sludge. Any help...
  11. jonelv

    Pump Curve Has a Maximum Head

    There should be no problem with a drooping head curve providing you are operating in the stable part of the curve - as per other comments. Drooping head curves are often desirable because of the greater efficiency Where you must be careful is if you wish to operate the pump in parallel with...
  12. jonelv

    Pumps and Stored Water Supplies

    If the pump is below the water level in the tank then you can use a split case so if the pump room floor is at the same level as the tank base you should be OK as BWL should be about the impeller level. If there is a static lift involved then you can't use split case (NFPA 20 3.1-2). Vertical...
  13. jonelv

    Jockey Pumps - FM Requirements

    Looking at previous threads on numbers of jockey pumps, I agree that one jockey pump makes sense for pressurisation of the firemains. However I'm currently looking at the design of a new system that will require three, possibly four separate diesel driven firepumps and have picked up a clause in...
  14. jonelv

    PID & DO control

    Panelman PID controls very common but you often use two or more to control the process. For example use a loop to control actual DO against DO setpoint in each aeration zone. You want to use a different loop to then control the blowers against an aeration set point. I have also been involved...

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