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  1. DavidCR

    Shear Lugs (Axial Stoppers) on Pipelines

    Lugs or clips can be calculated with formulas by Mohs or Kellog, and check stress on pipe with WRC 107. I´d use PVELite software lifting lugs analysis that include all that ( impact and ocassional loads factors can be considered). Ideally an analysis with NozzlePro software would be perfect for...
  2. DavidCR

    Custom o-ring 2m (78inch) flange flattness

    Hello and blessings to all. I need to specify the flange face flatness manufacturing tolerances for a flange with rubber o-ring seal. The flange is for a 2m diameter pipe custom design for cold water. I have the o-ring groove design and required finishes, but noy sure how to specify the...
  3. DavidCR

    Pipe wall thickness sizing

    The only good use of the burst pressure I´d recommend is to compare the safety factor of the code you are using and the safety factor of the manufacturer (commonly based on cold water pressure tests not on code comitee criteria). If your case is "special" and no public user can be related if...
  4. DavidCR

    NFPA2001 GAS SUPPRESSION SYSTEM

    I think you can include a maintenance keyed switch that cuts the energy to the solenoid so a manual mechanical release is the only way to discharge (keyed, controlled key use and lots of signs around, and trouble alert on panel).
  5. DavidCR

    Deluge sprinkler system for Ammonia

    What I see on MSDSs, deluge or mist is great for cooling/extinguishing ammonia containers. Of course the specific risk and site sould be analyzed by chemical risk expert in charge. There may be some issues with ammonia cloud control, icing of important parts, foam requirement, etc, but in...
  6. DavidCR

    Clean Agent System - Clarification Required.

    Would better refer it as 100% of design agent amount with more specific explanation about the trim depending of the system technology. If possible delete that requirement or change it as a more specific ítem optional cost information depending on clean agent system. A normal fast bidder would...
  7. DavidCR

    Determining maximum number of sprinklers on a main - hydraulic method

    If you have a hydrant or sprinkler grid where noise, vibrations or pressure loses where a high Reynolds number would be an issue or if you want a "balanced" system, it is a desirable option to consider velocity limits, but not a code requirement. For example, a well code design may worry...
  8. DavidCR

    Pressure for Class III Stand Pipe - NFPA

    It may be complemented with local or AHJ requirements. You go with class III and maybe a removable restricting device on 1.5 hose connection or hose valve may solve the class II req.
  9. DavidCR

    detectors in high humidity weather

    Most of the detector´s electronics are not for condensing wet environments. I have used aspirating type Vesda with a condensate trap (piece of transparent pipe with a manual drain before the device) and works fine so far (tropical forrest área power plant). It collects some cm of water on wet...
  10. DavidCR

    Maximum pressure allowed at ASTM A53 SCH40 GR B pipe.

    Yes, without the CA the required thickness would be 2.02mm. With a ca of =0, 6-Sch40 holds 1150psi aprox. With a ca of =2mm, 6-Sch40 holds 810psi aprox. This is approximate, many variables: check on respective ASTM if mill tol. is 12.5%, allowable stress is still 4.6kpsi on the current code...
  11. DavidCR

    Maximum pressure allowed at ASTM A53 SCH40 GR B pipe.

    I´d also choose B31.1 (2007) as an aprox. reference point. For a 6" inch pipe with an arbitrary 2mm corrosion allowance, the required thickness for 20bar at room temp is 4.02mm and 6"Sch40 is actually 7.1mm, so no problem with your pressure with SCH40. Smaller diameter same Sch are safe too and...
  12. DavidCR

    Decision to evacuate the workforce in case of fire

    On NFPA 72 a positive alarm procedure allows on certain conditions to prevent automatic alarm. Of course not all facilities have personnel to respond in such way, so not always apply and only if AHJ allows.
  13. DavidCR

    Jockey Pump on a Dry Pipe System

    That is what I was seeing, depending on how big is the system between the pump and the dry valve, you have a wet system to consider or not. Where is the limit? Other point is if the DPressure of pump at the start is too big, is it recommended to have JP to define a good star set point for the...
  14. DavidCR

    Jockey Pump on a Dry Pipe System

    I understand that downstream the dry valve the jockey pump is not involved nor needed, my doubt is if if the water supply (upstream) this valve need a pressure maintenance pump.
  15. DavidCR

    Jockey Pump on a Dry Pipe System

    So the line between the pump and the upstream side of the preaction valve is also dry? If so when the pump starts the water would fill or refill violently the pipes, is that Ok? I am missing something?
  16. DavidCR

    Jockey Pump on a Dry Pipe System

    Good question. Don´t have the answer. The main pump start point refers to JP set point to define start. If there is no JP how do you define start for the main? How do you keep the pipe upstream of the control (preaction) valve full?
  17. DavidCR

    Distance from AST diesel tank to power transmission line

    Thanks. By a google glance. What I´ve found is that the NFPA 30 is too general for this. And for the transmission lines it is supposed to be a responsibility of the power company to define the respective safety measures. So that´s what I´m supposed to be looking for.
  18. DavidCR

    Distance from AST diesel tank to power transmission line

    Hello dear everybody. Can somebody help me to find info or give hints on what security distances should be considered from a fuel oil #2 tank AST atmospheric fixed roof tank (28m diameter) from a power transmission line. (No problem, if not in USA, any country guidance would be appreciated).
  19. DavidCR

    Reservoir Size Calculation for Sprinkler and Hydrant System

    Always remember that the NFPA is not a design guide, it is a code or standard. It is easy to loose the North on this because the NFPA 13 or others include drawings, appendixes, etc., with many design guiding issues, but if you want to be a good fire protection engineer, do engineering, never...
  20. DavidCR

    Grooved vs Threaded Fittings

    I suppose that it is because it is easy and cheap to get leak tight threads on 1.5" or less, and on small sizes in general the amount of joints tend to multiply.

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