![]() ![]() In 1643 the French inventor and mathematician Blaise Pascal, realized that air (the atmosphere) also has weight and that its force is applied in all directions, not just down with gravity. For this reason, pumps are rated in "head" to express what we call pressure. (The topic of women’s liberation requires another article.)īeginning with the Archimedes screw and the Egyptian noria (another pumping device), pump force was rated in units of energy against gravity. It would also lift well water up to the surface for the wives to carry home and use to pour their husbands’ bath. The screw was used as a bilge pump on the king’s barge. The "Archimedes screw" would elevate water from a river up into an irrigation canal for agriculture. In Greece 2,200 years ago, Archimedes developed the first practical constant-flow pump. A certain amount of energy (force) was required to raise a jug of water from the fountain up into an oxcart or onto the housewife’s head. Still, it was generally understood that force (rated in units of energy) was required to elevate a quantity (volume or weight) of water against gravity. That was 2,600 years ago - when water flowed by gravity, the flow was dispensed in jugs and barrels, and there were no pressure gauges or instrumentation. A centurion normally guarded the fountain to prevent water theft or contamination. The water would collect in fountains for the housewives to carry away daily in clay jars. Underground clay pipes would carry the water by gravity to the different neighborhoods. Origins of head, pressureĪncient Rome and Greece were supplied with running water in giant aqueducts, which carried fresh water from mountain lakes and streams down into the city. As someone who specifies and/or installs pumps, you need to know how these terms relate to each other. In the final analysis, they are the same, just expressed from two different points of view. Pump manufacturers supply feet (or meters) of head. This misunderstanding about head and pressure occurs daily all over the country … and, indeed, all over the world. Indignantly, I walked away and went to a competing industrial supply house - where I repeated the same verbal exchange with their sales rep. I wondered why the sales rep used different terms. The requisition chit clearly stated 30 psi. What is 70 feet of head?" I thought the sales rep was trying to do a "bait-and-switch" on me. I said, "Wait a minute! I don’t need 70 feet of head. ![]() He said, "This is the water pump you need. ![]() " He wrote it on the requisition.Īt the industrial supply house, the sales rep escorted me to the pump showroom. He said, "Get a water pump that pumps 30 psi at 400 gpm. He told me to go into the city and purchase another pump at the industrial supply house. When one of our water pumps failed in the cooling ponds one day, my boss gave me a requisition order and the keys to a company truck. Random PRESSURE units millimeter of mercury foot of water 15.Back in the mid-1960s, I was employed as an apprentice mechanic in a Birmingham, AL, steel mill. In relation to the base unit of => (pascals), 1 Psi (psi) is equal to 6894.7572932 pascals, while 1 Foot Of Mercury (ftHg) = 40636.66 pascals. How to convert Psi to Foot Of Mercury (psi to ftHg)?ġ x 0.16966840515928 ftHg = 0.16966840515928 Foot Of Mercury.Īlways check the results rounding errors may occur. The base unit for pressure is pascals (Non-SI Unit) ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |