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Posted: 8/25/2023 11:38:59 AM EDT
A column of water 100' high and 1" thick has as much pressure at the bottom as a dam 100' high and hundreds of acre feet in volume.
Link to video. Dad got me into snorkel/scuba diving when I was 14 or so. I asked him "why are snorkels so short?" He cut a 3' length of PVC, put a couple of elbows on it and sent me to the shallow end of the pool. I Could Not Breathe beyond about 18"! The water pressure was too great. The same concept was demonstrated when they pressure tested the fuel tanks on the Rutan Voyager aircraft. They hoisted a garden hose 50' up the side of the hangar and connected it to the fuel tank and kept adding water till the tank deformed. |
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FYI...
For every 2.3 ft of vertical water depth, the pressure increases by 1 psi. It's even more for salt water. -ZA |
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You've see those giant steel storage tanks for oil?
The ones with a closed roof typically have an extremely low design pressure, sometimes 2" of water. Theoretically if they didn't leak, the safety relief devices were disabled, and you had enough time, you could burst them using your lungs to over pressure the steel tank. Human lungs are typically capable of generating a pressure equal to around 20" of water column. They are remarkably fragile. |
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When I was a kid all the kids in the neighborhood would dive and snorkel and dive off the boat docks in the keys. Someone had the bright idea to bring a garden hose so we could breathe under water. I found out real quick that you cant go very deep under water and breathe through a pipe. Also garden hose isn't made for outside pressure, its meant to hold pressure in, so the hose would collapse a few feet down and shut off the air.
I once tried as an adult to breathe underwater through a 2" pool pipe open to the air. This hose is designed to not crush with a vacuum applied. I could just barely breathe at 4 feet down but I had to strain amazingly hard to do it. 5 feet would have been impossible. but I could do 4, just barely. I want to try taking my old CPAP machine out of storage and see if I can use it under water in the pool, or maybe mod it for pool use. . Mine uses a mask which covers my nose and mouth. |
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Quoted: You've see those giant steel storage tanks for oil? The ones with a closed roof typically have an extremely low design pressure, sometimes 2" of water. Theoretically if they didn't leak, the safety relief devices were disabled, and you had enough time, you could burst them using your lungs to over pressure the steel tank. Human lungs are typically capable of generating a pressure equal to around 20" of water column. They are remarkably fragile. View Quote You're saying that huge tanks that are designed to hold a bunch of oil are only capable of holding the pressure of just a few inches of water? I don't think I am understanding what you are trying to say. |
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She seems kind of geeky, but I'd like to put pressure in her ass.
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Yes, Katerina is a cutie and musically talented too.
![]() KATERINA VISNJIC - SERBIAN TANGO |
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In Boy Scouts we did a demonstration similar to that where kids on the second story of the church poured water into a hose and lifted a patrol worth of Scouts.
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In the fire service we called it atmospheric or head pressure. We had a standard of 5 p.s.I. Per floor to overcome head pressure, in addition to other friction loss calculations to achieve proper nozzle pressure on, say the 10th or 12th floor the pumper would be screaming.
Hence the reason you can’t pump water up 100 floors. |
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Princeton physics and they're learning what most people learn in high school? WTF?
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Quoted: Also, water is in fact compressible. View Quote Yeah it is. . It's just that it isn't so highly compressible compared to say... the the air we breathe . It's relative. I did the math then that sub imploded. I don't remember the exact numbers the sub was at but at the depth it was when it popped the water was being compressed by about 4-5% volume compared to at the surface. |
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Quoted: In the fire service we called it atmospheric or head pressure. We had a standard of 5 p.s.I. Per floor to overcome head pressure, in addition to other friction loss calculations to achieve proper nozzle pressure on, say the 10th or 12th floor the pumper would be screaming. Hence the reason you can’t pump water up 100 floors. View Quote Don't skyscrapers have tanks on the upper floors for flushing toilets and such? |
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Quoted: Well, it has to be somewhat compressed if you are going to be able to breath it deeper than 4 feet or so underwater. If only there was a way to regulate the pressure.... View Quote It has to be really compressed to breath it underwater. It has to come out at just above two atmospheres (above standard atmospheric pressure) to breath it at 66ft. Google says this is almost 30psi of pressure. I have breathed compressed air plenty of times (both in the water and out). As far as I know, it has never hurt me. It has always been regulated to breathing air pressures. |
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If you have a plugged field tile you will see the force of water & gravity as it blows out an upward hole.
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Quoted: In the fire service we called it atmospheric or head pressure. We had a standard of 5 p.s.I. Per floor to overcome head pressure, in addition to other friction loss calculations to achieve proper nozzle pressure on, say the 10th or 12th floor the pumper would be screaming. Hence the reason you can't pump water up 100 floors. View Quote |
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Quoted: Well, it has to be somewhat compressed if you are going to be able to breath it deeper than 4 feet or so underwater. If only there was a way to regulate the pressure.... View Quote View All Quotes View All Quotes Quoted: Quoted: Don’t breathe compressed air Well, it has to be somewhat compressed if you are going to be able to breath it deeper than 4 feet or so underwater. If only there was a way to regulate the pressure.... When you think about what a scuba 2nd stage regulator (the thing in your mouth) does and just how amazingly simply it is you’re amazed. Breathing at 130 feet as easy as 0 feet. It exactly matches outside water pressure and delivers air at same pressure. Outherwise your lungs implode. I’m sure you knew that on the regulate emphasis. ![]() |
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Quoted: In the fire service we called it atmospheric or head pressure. We had a standard of 5 p.s.I. Per floor to overcome head pressure, in addition to other friction loss calculations to achieve proper nozzle pressure on, say the 10th or 12th floor the pumper would be screaming. Hence the reason you can’t pump water up 100 floors. View Quote I read somewhere that to pump water up the space needle they have a plan of two pumpers in series to get enough pressure. I wouldn't want to be anywhere near those hoses. |
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Quoted: I read somewhere that to pump water up the space needle they have a plan of two pumpers in series to get enough pressure. I wouldn't want to be anywhere near those hoses. View Quote View All Quotes View All Quotes Quoted: Quoted: In the fire service we called it atmospheric or head pressure. We had a standard of 5 p.s.I. Per floor to overcome head pressure, in addition to other friction loss calculations to achieve proper nozzle pressure on, say the 10th or 12th floor the pumper would be screaming. Hence the reason you can’t pump water up 100 floors. I read somewhere that to pump water up the space needle they have a plan of two pumpers in series to get enough pressure. I wouldn't want to be anywhere near those hoses. I’m sure the math on exactly what pressure is required is east. 1 atm (14.7 psi) every 33 feet roughly. |
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Quoted: You've see those giant steel storage tanks for oil? The ones with a closed roof typically have an extremely low design pressure, sometimes 2" of water. Theoretically if they didn't leak, the safety relief devices were disabled, and you had enough time, you could burst them using your lungs to over pressure the steel tank. Human lungs are typically capable of generating a pressure equal to around 20" of water column. They are remarkably fragile. View Quote The diaphragm on the vent is around +/- 15 psi. They can hold 400 barrels of water. Thats 16,800 gallons of typically salt water |
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Quoted: A column of water 100' high and 1" thick has as much pressure at the bottom as a dam 100' high and hundreds of acre feet in volume. Link to video. Dad got me into snorkel/scuba diving when I was 14 or so. I asked him "why are snorkels so short?" He cut a 3' length of PVC, put a couple of elbows on it and sent me to the shallow end of the pool. I Could Not Breathe beyond about 18"! The water pressure was too great. The same concept was demonstrated when they pressure tested the fuel tanks on the Rutan Voyager aircraft. They hoisted a garden hose 50' up the side of the hangar and connected it to the fuel tank and kept adding water till the tank deformed. View Quote Yup. Same principal for why one of the units used for barometric pressure is quoted as "inches of mercury" (usually written inHg). They also tried water, initially, but water is far less dense than mercury, and 1 inHg = 13.6 inches of water column. You'd need a ridiculously long column of water for barometric pressure. |
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Quoted: Yup. Same principal for why one of the units used for barometric pressure is quoted as "inches of mercury" (usually written inHg). They also tried water, initially, but water is far less dense than mercury, and 1 inHg = 13.6 inches of water column. You'd need a ridiculously long column of water for barometric pressure. View Quote View All Quotes View All Quotes Quoted: Quoted: A column of water 100' high and 1" thick has as much pressure at the bottom as a dam 100' high and hundreds of acre feet in volume. Link to video. Dad got me into snorkel/scuba diving when I was 14 or so. I asked him "why are snorkels so short?" He cut a 3' length of PVC, put a couple of elbows on it and sent me to the shallow end of the pool. I Could Not Breathe beyond about 18"! The water pressure was too great. The same concept was demonstrated when they pressure tested the fuel tanks on the Rutan Voyager aircraft. They hoisted a garden hose 50' up the side of the hangar and connected it to the fuel tank and kept adding water till the tank deformed. Yup. Same principal for why one of the units used for barometric pressure is quoted as "inches of mercury" (usually written inHg). They also tried water, initially, but water is far less dense than mercury, and 1 inHg = 13.6 inches of water column. You'd need a ridiculously long column of water for barometric pressure. I use InH2O. But for differential pressure to calculate cubic feet of gas |
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Yep. It's another reason why water pressure and electrical voltage are analogous.
That long thin column can exert a lot of pressure, but can't do as much work as a long thick column. Volts is to pressure and Amps is to volume. |
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Quoted: When I was a kid all the kids in the neighborhood would dive and snorkel and dive off the boat docks in the keys. Someone had the bright idea to bring a garden hose so we could breathe under water. I found out real quick that you cant go very deep under water and breathe through a pipe. Also garden hose isn't made for outside pressure, its meant to hold pressure in, so the hose would collapse a few feet down and shut off the air. I once tried as an adult to breathe underwater through a 2" pool pipe open to the air. This hose is designed to not crush with a vacuum applied. I could just barely breathe at 4 feet down but I had to strain amazingly hard to do it. 5 feet would have been impossible. but I could do 4, just barely. I want to try taking my old CPAP machine out of storage and see if I can use it under water in the pool, or maybe mod it for pool use. . Mine uses a mask which covers my nose and mouth. View Quote Don't go deep. Also, it's going to smell and taste bad. lol |
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My favorite statement about pressure: They'd be crushed to jelly at that depth!
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Quoted: That's how much I think of northern women. View Quote View All Quotes View All Quotes |
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Quoted: Just use a run of the mill air compressor and adapt the output to your hose. Don't forget to regulate the outlet pressure as far as you can before starting and test without it attached to your face. You can always increase it. Blowing 40 psi directly into your mouth and nostrils is going to hurt. Don't go deep. Also, it's going to smell and taste bad. lol View Quote View All Quotes View All Quotes Quoted: Quoted: When I was a kid all the kids in the neighborhood would dive and snorkel and dive off the boat docks in the keys. Someone had the bright idea to bring a garden hose so we could breathe under water. I found out real quick that you cant go very deep under water and breathe through a pipe. Also garden hose isn't made for outside pressure, its meant to hold pressure in, so the hose would collapse a few feet down and shut off the air. I once tried as an adult to breathe underwater through a 2" pool pipe open to the air. This hose is designed to not crush with a vacuum applied. I could just barely breathe at 4 feet down but I had to strain amazingly hard to do it. 5 feet would have been impossible. but I could do 4, just barely. I want to try taking my old CPAP machine out of storage and see if I can use it under water in the pool, or maybe mod it for pool use. . Mine uses a mask which covers my nose and mouth. Don't go deep. Also, it's going to smell and taste bad. lol Lol! Don’t do this. I mean what could possibly go wrong? Rust in lungs is the least concern. |
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Pressure=gravity*height* density of liquid. No one thinks physics be, but it do.
The only thing that matters is the height of the column of fluid for pressure not how wide it is. |
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Quoted: A column of water 100' high and 1" thick has as much pressure at the bottom as a dam 100' high and hundreds of acre feet in volume. Link to video. Dad got me into snorkel/scuba diving when I was 14 or so. I asked him "why are snorkels so short?" He cut a 3' length of PVC, put a couple of elbows on it and sent me to the shallow end of the pool. I Could Not Breathe beyond about 18"! The water pressure was too great. The same concept was demonstrated when they pressure tested the fuel tanks on the Rutan Voyager aircraft. They hoisted a garden hose 50' up the side of the hangar and connected it to the fuel tank and kept adding water till the tank deformed. View Quote I have a picture of the voyager in flight, signed by the entire flight crew |
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That is correct...does not matter how large the area is above, pressure is height dependent only.
I remember a problem we had in Fluid Mechanics in college, for a given tank height how long does a pipe with a given friction loss have to be such that no water flows out the end. |
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Quoted: FYI... For every 2.3 ft of vertical water depth, the pressure increases by 1 psi. It's even more for salt water. -ZA View Quote Working in the refineries for close to 40 years, we had thousands of instruments that needed to be calibrated...so one factor we always remembered, 400" of water = 15.025 PSI 400 / 12 = 33.33 feet 33.33 feet / 15.025 = 2.22 ft/psi I used 15.025 because that is our base at sea level, if you used the more common 14.7, then 33.33/14.7 = 2.27 ft/psi |
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Quoted: You're saying that huge tanks that are designed to hold a bunch of oil are only capable of holding the pressure of just a few inches of water? I don't think I am understanding what you are trying to say. View Quote View All Quotes View All Quotes Quoted: Quoted: You've see those giant steel storage tanks for oil? The ones with a closed roof typically have an extremely low design pressure, sometimes 2" of water. Theoretically if they didn't leak, the safety relief devices were disabled, and you had enough time, you could burst them using your lungs to over pressure the steel tank. Human lungs are typically capable of generating a pressure equal to around 20" of water column. They are remarkably fragile. You're saying that huge tanks that are designed to hold a bunch of oil are only capable of holding the pressure of just a few inches of water? I don't think I am understanding what you are trying to say. |
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Quoted: You're saying that huge tanks that are designed to hold a bunch of oil are only capable of holding the pressure of just a few inches of water? I don't think I am understanding what you are trying to say. View Quote @FF208 Yes, the giant 50,000 barrel plus storage tanks, not home hearing oil tanks. Many are floating roof, but the enclosed cone roof tanks are only capable of holding a few inches of water pressure above the liquid level. The seam between the roof and the shell is typically the weak point. Remember, pressure acts on surface area and these tanks have enormous surface area. Edit to add: Take a 100' diameter tank. the surface area of the roof is greater than 1,130,973 square inches. ( I assumed a flat roof rather than a cone because I'm lazy.) An internal pressure equal to 2" of water column puts a force of 81,656 pounds on the roof. |
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Quoted: Lol! Don’t do this. I mean what could possibly go wrong? Rust in lungs is the least concern. View Quote Yeah, bad idea. Most compressors will blow contaminants like oil, good way to get pneumonia at the least. There are special compressors called hookah made specifically for shallow diving. ![]() |
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