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  1. greg87

    P&ID question that is driving me nuts

    Ideally each unit process should have its own P&ID. [however, occasionally more than one drawing may be needed so it is not too congested.] A key consideration is how you intend to organize the numbering for the equipment and instrumentation. A systematic numbering system is important, and...
  2. greg87

    Total Backpressure at Actual Capacity of PSV

    The primary issue is that at the point that the discharge line's pressure drop exceeds about 10% of set point (8 psi) a conventional valve will close. It will then reopen as soon as the backpressure descreases, and so on. This rapid and possibly violent opening and closing can damage and...
  3. greg87

    Compendial quality grade for water used in lab analytical testing

    The water quality must be based on the tolerance that the analytical tests have for the contaminants that are found in water. Your chemists will need to provide you those guidelines based on the type of testing they will perform and the required accuracies etc. The information on the web site...
  4. greg87

    Corrosion resistance of 316L SS vs 304 SS

    I agree with previous to use 316L. The cost difference is minor, overall. Not clear from your question if these parts are in contact with product/process, or external. If in contact, product quality drives material and finish, and may require some degree of polish. Electropolish would only...
  5. greg87

    Materials selection for RO treated water

    Plastic tanks or appropriate fiberglass is appropriate for RO water
  6. greg87

    DI Water and Metal Corrosion

    I’d like to understand why high purity waters apparently cause high corrosion rates of carbon steel at room temperatures. Is the higher corrosion rate really due to their low ion content, & therefore higher dissolution driving force (ie hungry water explanation)? Is the rate for pure water...
  7. greg87

    Minimum Pipeline Flow

    I interpret your question as: you would like to know what is the lowest flow rate that would be typically found in typical industrial pipes, for insight into what flows your “device” may encounter. If my interpretation is correct, then: A "usual" range would be 5 to 8 fps, with velocities...
  8. greg87

    Pressure Relief System in a Production module-Bulk Drug(API) Manufactu

    I would also recommend against a flame arrestor on the relief discharge line. With proper location and position of the discharge point, it should not be required. I'm not sure why they would be questioning pressure relief for the tanks, "since the area is surrounded by a corridor" Sounds more...
  9. greg87

    cooling a di process water storage tank

    Since most of the temperature rise is due to the addition of the pump energy, you may want to look at the loop hydraulics to see if you can reduce the flow rate, or the pressure drop. If you can, then you can reduce the pumping power by using a smaller impeller or by using a VFD on the pump...
  10. greg87

    Section VIII Operating Pressure Clarification

    In ASME Section VIII (one of ) the criteria that determines is a vessel is covered in the code is if the “operating pressure” is 15 psig or higher. There are some cases where the codes definition of “operating pressure” is not clear to me. Maybe best using a hypothetical: Let’s presume...
  11. greg87

    Rupture Disc for Hot WFI storage tank

    Since your tank is rated for full vacuum there is no reason to use a disk to protect the tank against vacuum. Not sure what kind of "hot water tanks" were being referenced in the article you read. Your vent filter should be properly sized to ensure that enough air can come through...
  12. greg87

    Cooling purity water without a exchanger.

    I don't know anything about your system, but for many pure water systems the reason that the system temperature is increasing is due to the heat input from the recirculation pumps. Almost all the brake horsepower of your pumps is converted to heating the water (for recirculating systems)...
  13. greg87

    Design of overflow drainer for deionized water tank

    The best approach is to eliminate the open overflow and provide a sanitary rupture disk on the top of tank with a discharge line to the floor/drain. This will prevent overfilling, or overpressure due to any problem. A high level switch will still help avoid high level problems and prevent the...
  14. greg87

    Water Hammer / Pressure Surge in Sanitary System

    I would agree that the best approach is to look for the source of the hammer. A VFD on the pump(s) could be used to ramp up and ramp down may help. Slow (slower) closing valve actuators might help. Any chance that vaporization is occurring (and collapsing) in some part of the line? The only...
  15. greg87

    How to clean and disinfect new purity water system pipe before star up

    PauloRibeiro is correct that if the system is stainless steel, then it must be passivated prior to sanitization, as I stated. The actual water spec for your “high purity” system may impact what really needs to be done. Stainless steel high purity water systems would normally use stainless...
  16. greg87

    How to clean and disinfect new purity water system pipe before star up

    Sanitization can be performed with chemicals: hydrogen peroxide or peracetic acid solutions. Makeup a dilute solution in the tank and circulate through the system. Draw off at each use point to ensure exposure to all piping. After a period of time, flush. Sample to ensure no residual...
  17. greg87

    Steam flow to clean in place

    Your wording about clean-in-place and steam in place are somewhat confusing. To sterilize in place (SIP) the unit using clean/pure steam you would heat it from 70 F to 250 F(121 C) and then hold at 250 F. Saturated steam pressure at 250 F is about 15 psig. You should use at least 20 psig...
  18. greg87

    Transition from pressure to gravitional flow.Possible?

    BobPE: I agree with your conclusion that "The high point in your system is the point you want to design for in your calculations.", which is exactly what I stated in my response. I do not think Carlets will lose his job if he follows that advice. I also agree that the best design...
  19. greg87

    Transition from pressure to gravitional flow.Possible?

    I responded to this same question in a different forum, but since there are different participants (and information) here, I would like to respond again. The answer to your original question is: Yes, you can just size the pump based on the total frictional loss plus the elevation up to the...
  20. greg87

    Humidification with pure water and corrosion

    We had an application which used steam generated from a "clean steam" generator for humidification. The steam generator used DI water as feed. After a relatively short (?)period of time, the galvanizing on the ductwork downstream of the humidifier was almost gone. There had been...

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