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  1. erbru

    Vacuum resistance of two similar vessels

    I was expecting that answer. They (site) don't really want to pay for as it involves removing insulation from the tank, measuring all the way up (5m), putting it back on, paying for all this & will probably argue that we can size the vacuum protection on current operating data. If it was my...
  2. erbru

    Vacuum resistance of two similar vessels

    Hi another question on resistance to external pressure If I have water two storage vessels, one marked 'atmospheric' and protected at 100 mbarg and one rated at 1 barg, of a very similar shape, size and diameter and the same material (stainless steel), and having been in the same service...
  3. erbru

    Determine Vessel wall thickness and external and internal pressure resistance

    No offense taken. I should have known really that pressures are always in gauge. It's just that I've been doing ideal gas law calculations with absolute units today (and I obviously don't have the pressure vessel engineer's reflex). I am well aware this is dangerous and I will make sure the RV...
  4. erbru

    Determine Vessel wall thickness and external and internal pressure resistance

    It was bought second hand and previously used for milk storage as far as we know. There is an unused heating element inside the vessel. It's now used to store water at atmospheric pressure and temperature. It is stainless steel and currently protected at 100 mbarg by a (very probably undersized)...
  5. erbru

    Determine Vessel wall thickness and external and internal pressure resistance

    The manufacturer has gone out of business and is uncontactable. This was built in 1995 in France. They have a design code called CODAP for Vessels but no idea if this was designed to it. It's pretty frustrating, being asked to set a relief valve for both the vacuum and overpressure scenarios...
  6. erbru

    Determine Vessel wall thickness and external and internal pressure resistance

    I am working for a client who has an stainless steel low pressure vertical water tank for which there is no technical data or drawings It has a useable volume of 33.8 m3 (from nameplate) and has a diameter of approx 3m and height 5m The nameplate also says: S 1 bar PE 1.5 bar (this is France...
  7. erbru

    Relief case water vaporisation in low pressure tank

    Unfortunately this case is excessively high and won't be relieved through a 50 mm orifice which is what I have available. I need to get a more reasonable flow.
  8. erbru

    Relief case water vaporisation in low pressure tank

    On a little further refelction, isn't the simplest sizing basis to say the tank is empty, heats up extremely quickyl and all the hot water coming in turns to water vapour and all of this water vapour needs evacuating to keep the pressure down. That means my sizing case is 5500 kg/hot water -->...
  9. erbru

    Relief case water vaporisation in low pressure tank

    Hi all This is related to my thread on the vacuum pulling due to steam condensation in the atmospheric tanks. http://www.eng-tips.com/viewthread.cfm?qid=412869 I am trying to quantify all the possible relief scenarios One of the cases (which I think is not decisive) is a blocked-in vent during...
  10. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    A little update: After hunting further I stumbled across this very handy calculation tool down by Art Montemayor (some of you may have heard of him) for the 'steam out' of tanks and he has even done a simple model of rain landing on the tank during this process. I ran the numbers in his...
  11. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Hi again I totally agree that it is better to stop the event occurring. The fact is that the vessel must be sanitised due to the pharmaceutical industry's requirement. And changing the water vessel storage temperature to shock the microorganisms is the way this is done (chemical sanitisation...
  12. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    A longer duration picture of the overall process from start of recirculation to about 6 m3 of level. Note the stabilising out of the temperature. I guess the thermowell is starting to get submerged at this...
  13. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Tank pressure variation during the initial heat up phase (addition of the first 1-2 m3 of water) and before recirculation. The steam is vented from the tank every 10 minutes or so as the vapour pressure reaches above 10 mbar. No air is injected. The venting happens via the filter on the tank and...
  14. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Tank during the later heat up phase (some time after the start of recirculation, level of around 4 m3) This is a much slower process than the condensation just after the recirculation starts. The injections of air occur every 10 minutes of...
  15. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Forty second snapshot around the start fo recirculationhttp://files.engineering.com/getfile.aspx?folder=b5301698-42a4-49ba-acc4-2b87b561664b&file=40_seconds_start_recirc_(Small).JPG
  16. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    One min snapshot around the start of recirculationhttp://files.engineering.com/getfile.aspx?folder=8aaf5eb4-d477-4390-b0fa-d8594770d6a4&file=1_minute_start_of_recirc_(Small).JPG
  17. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Another curve (longer time period)http://files.engineering.com/getfile.aspx?folder=b2b46011-c6ff-4ef6-bbf3-ae43a70c96fa&file=20_minutes_during__filling_with_hot_water_+_start_recirc_(Small).JPG
  18. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    Hi again all Can I just say I appreciate all your input. Thanks for replying with your ideas. The red trace line on the previous chart is actually a pressure measurement elsewhere (another (correctly rated!) hot water tank which receives hot water from the same source) so not relevant. The...
  19. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    I am trying again to attach the file on pressure fluctuations The process starts between 13:48 and 17:36 on the time axis. Green : pressure in bar (-0.05 to + 0.05 bar => - 50 to +50 mbar) Blue : tank level (0 to 25 m3) Black: tank temperature (0 to...
  20. erbru

    Steam collapse - pulling vaccum in a water tank - help please

    I should clarify : the tank is a pharmaceutical water for injection tanks with no free vent to air permitted for hygienic reasons. It is fitted with a hygienic vent filter but from pressure fluctuations seen on the tank we know it is insufficient for the condensaton case. It just about cover...
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