00:00Welcome to our channel in today's short session we will try to understand if we need a line which
00:06is to be designed for steam or any vessel which is to be designed for steam out or which may
00:12handle steam why that vessel or a line needs to be designed for a full vacuum and this is also
00:19we will try to understand with some small example mathematical example and then we will come to know
00:24why this is required so let us understand first what is steam and water so suppose one at one
00:34atmospheric pressure steam occupies around 16 to 1700 times more volume than the water so it means
00:41one liter of water can produce 1600 to 1700 liters of steam at 100 degrees c and one atmosphere so
00:50this is the difference so suppose we have a vessel which is having approximately volume of one meter
00:55cube okay with the pressure of 2 bar g so which is equal to 43.7 psi i just convert
01:04because we have
01:05to go in absolute condition so it is converted to psi at temperature of 135 degrees centigrade
01:12so if you know the atmospheric pressure is 14.5 psi a so if you minus from 43.7 it
01:23comes around 29.2 psi
01:25which is acting on the from inside to the outside of this vessel suppose at 135 the specific volume of
01:36this steam is the vs is equal to 0.65 uh 0.605 which you can get from the steam
01:43table at this temperature
01:46so to calculate the mass of because you know the volume can be changed but the mass of the
01:52any uh fluid remains same so that's why we always calculate in the marks or kgs so based on the
02:00specific
02:01volume so uh specific volume so volume upon specific volume gives you the uh mass which is kgs so if
02:08you
02:08one meter cube divided by 0.605 meter cube per kg so you will get the mass of the uh
02:16that fluid or you
02:16can say steam or a water is 1.65 kg suppose this steam drum or this get cooled by the
02:25atmospheric uh temperature
02:27or whatever any reason to 25 degree then then at 25 degree centigrade the specific volume of a liquid
02:41which is only the 0.001 meter cube per kg because we calculate first the specific volume at the uh
02:47for
02:47steam and if you see in the steam table at the 25 degree you find the specific volume is 0
02:53.001
02:54so mass of steam when it is at 25 degrees centigrade or you can say the fluid liquid basically
03:01we we have that volume the kgs is 1.65 kg so now we calculate the volume now so new
03:07volume of the
03:08liquid is 165 uh 1.65 kgs into 0.001 meter cube which is a specific volume previously we calculated
03:17from
03:17the volume to the kgs now we are just reversing it kg to the volume so the volume of of
03:23your steam at 25 degree centigrade comes around 0.00165 meter cube which is 1 meter cube earlier
03:32now it is remains only 165 when the temperature change from 135 degree centigrade to 25 degree means
03:39it is getting condensed or you can say cooled down so at 25 degree centigrade your volume in this vessel
03:48steam volume or you can say it got condensed and the volume remains only 1.65 liter and there is
03:54a void
03:54space of 998.35 liter in this vessel so at this 25 degree centigrade you if you get the vapor
04:04pressure
04:04of your liquid or water it is coming around 0.05 psi a absolute and you know the atmospheric pressure
04:13pressure is 14.25 psig per square inch which is acting from the outside to the inside of this vessel
04:20and inside pressure is only 0.45 so if you if you go in more detail and you find the
04:27four you know the
04:27force per area is equal to force per area is equal to area into pressure so now suppose this area
04:35surface
04:36area is 1 meter square is 1 meter square which is equal to 1550 inch square because we have this
04:42is in inches
04:44so force acting on this vessel is 1150 uh 1150 inch square into 14.25 lb which is comes around
04:5522,087 lbs
05:01so if you convert this into tons it comes around 10 tons so if you understand by this example that
05:07there are almost 10 tons of force acting on this vessel so if you not design this vessel for the
05:13full
05:13vacuum this will get ruptured or you can say this will get buckled so this way we can understand why
05:22we
05:23need full vacuum for any line or a vessel so thank you very much write your question and comment i
05:31will
05:31be happy to answer it you can reach us on conceptengineering2025 at gmail.com
05:40links and links for the other sessions are given in this description
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