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  1. mechconst

    Operating VFD above 60 Hertz on pumps

    Has anyone been involved in a project where the limits on a VFD were set above 60 Hz in order to get the pump to increase RPM's and maximum flowrate? Pumps in question are submersible 125 horsepower, 460 volt and operate on VFD's. I've never seen this done and it doesn't seem to be an industry...
  2. mechconst

    Cryogenic Globe Valve Flow Direction

    The valve is used for isolation of each vaporizer. There are three vaporizers in parallel, with a globe valve on the upstream side, and a motorized ball valve on the downstream side.
  3. mechconst

    Cryogenic Globe Valve Flow Direction

    Can the flow direction on this type of globe valve be in either direction? The service is liquid oxygen with this valve located on the upstream side of the liquid oxygen vaporizers. There is a flow arrow on the side of the valve, but why would it matter if the flow is pushing up on the disc or...
  4. mechconst

    Rookie question; tapping water lines.

    The best thing to do is shut the line down and drain it if you can. If that's not an option, then they make fittngs that can be clamped on the pipe such as a service saddle, tapping sleeve, or even a PVC "Clamp it Tapping saddle" by Harrington Plastics. In my experience the contractor...
  5. mechconst

    ASME Stainless Steel Vessel 2B Finish

    Our project has a 316L stainless steel pressure vessel, 48" diameter with ASME F&D heads that operates under 30 psig. The engineered spec indicates that the vessel is to have a Bright 2B Finish. Question: is the "Bright" 2B finish something performed at the steel mill or is this something...
  6. mechconst

    Pump Power Factor Correction Capacitor

    Thanks for all the responses. I found some information in the electric motor spec indicating it's required in order to raise the motor power factor to approx. 95%.
  7. mechconst

    Pump Power Factor Correction Capacitor

    What is the purpose of having to install a Power Factor Correction Capacitor locally at a pump? I have never seen one before. Pump is 7.5 HP / 460 volt/3 phase/60 / 10.1 FLA. This pump is within a typical plant feed from the Motor Control Center.
  8. mechconst

    Xref path change

    I am using Autocad LT 2002. Where would the reference manager be?
  9. mechconst

    Xref path change

    I received a copy of a project on CD with over 500 drawings along with the Xref files for use in construction, however, when I open the drawings on my computer I only see a partial of the drawing. I can manually edit each drawing Xref path, so that it finds the Xref drawing on the CD in oder to...
  10. mechconst

    Reading Control Diagrams

    Was wondering if anyone could refer me to a good website or book that provides a practical guide to reading and understanding one line diagrams and control diagrams. The application would be in industrial plants dealing with motor controls for pumps, valves, meters, instrumentation, etc.
  11. mechconst

    Diesel fuel piping?

    1) In the field, black iron pipe commonly refers to carbon steel pipe such as A53, A106, A120 etc. without a galvanized, painted, or tape coating. 2) Typically it is socket welded sch 80 for 2 inch and smaller. Hook ups to the generator should be an approved flexible hose, as opposed to hard...
  12. mechconst

    MCC room construtability

    Sparkyman, thanks for your help. Yes, the room will will have two separate door ways.
  13. mechconst

    Checking Bolt Torque

    I'm not sure what the application is, but I run across this in the field all the time in structural bolt ups, using high strenght bolts: A325 and above, 5/8" dia. and larger. Other methods are: 1) use load indicating washers. They have a series of raised points on the washer that flaten...
  14. mechconst

    MCC room construtability

    I'm looking at installing 3 stand alone MCC panels in an existing small room at a process plant. They measure 2.5 feet wide and vary between 16 to 24 feet long: controls for about 30 motors with 3 VFD's. Access is only through a doorway. My questions are: 1) are the units normally shipped in...
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