Fluid pressureGauge pressure and ab

Fluid pressure

Gauge pressure and absolute pressure

Pressure is the amount of force acting on an area. When fluids (liquids or gases) are under pressure they exert pressure on the surfaces of the tanks, pipes, etc., that hold them.
Examples of pressurized fluids are compressed air inside air hoses, compressed gases such as propane in gas cylinders, and water mains. The SI measurement of pressure is the Pascal. One Pascal is equal to one Newton per square metre (1Pa = 1N/m2). However, many pressure gauges (devices which measure pressure) use the imperial measurement pounds per square inch (psi). Pressure can also be measured in bars. One bar is roughly equal to atmospheric pressure – that is, the pressure of the air in the atmosphere – at sea level. For example, four bars, or four bar – which can also be described as four atmospheres – is four times atmospheric pressure.
When engineers calculate the pressure of a fluid inside a vessel, they usually calculate its gauge pressure. This is the pressure differential – the difference in pressure – between the fluid inside the vessel and atmospheric pressure outside. Therefore, with gauge pressure, it is assumed that the atmosphere has a pressure of zero Pascals – even though this is not true. Engineers use gauge pressure because they need to know if a fluid inside a vessel is at higher pressure or at a lower pressure than the outside air (the air in the atmosphere), and if it is, by how much. This allows them to design tanks and pipes so that they do not fail dangerously by exploding if their gauge pressure is positive, or by imploding if their gauge pressure is negative.
Pressure can also be measured by comparing it with a vacuum – a void containing no gas or liquid, as in space, where pressure is truly zero Pascals. Pressure compared with a vacuum is called absolute pressure. The absolute pressure of the atmosphere at sea level is approximately 1000.000 Pascals (or 100 kilo-Pascals). Therefore a partial vacuum – which is below atmospheric pressure but is not a perfect vacuum – has a positive pressure when it is measured as an absolute pressure, because it has a higher pressure than a perfect vacuum. But it has a negative pressure when it is measured as a gauge pressure, because it has a lower pressure than the atmosphere.

Hydrostatic pressure and siphonic action

In liquids – most often in water – pressure and flow can be generated by hydrostatic pressure.
An example is a water tower which supplies drinking water to homes. Water is stored in the tower at a high level, so that the water pushes down. This is called a head of water. It puts the water at lower level (in the water main) under pressure. If the height of the water tower is increased, this will increase the water pressure at low level. Smaller tanks located at a high level to generate hydrostatic pressure – at the tops of buildings, for example – are called header tanks.

Результаты (русский) 1:

Давление жидкостиДатчик давления и абсолютного давленияДавление-это количество силы, действующей на площади. Когда жидкости (жидкостей или газов) находятся под давлением, что они оказывают давление на поверхностях танков, трубы и т.д., которые держат их.Под давлением жидкостей примеры сжатого воздуха внутри воздушных шлангов, сжатые газы, такие как пропан, газовые баллоны и водопровода. SI измерение давления является Паскаль. 1 паскаль соотвествует 1 Ньютон на квадратный метр (1ПА = 1Н/м2). Однако многие Манометры (устройства, которые измеряют давление) использовать имперского измерения фунтов на квадратный дюйм (psi). Давление может также быть измерено в барах. Один бар примерно равна атмосферное давление – то есть, давление воздуха в атмосфере – на уровне моря. К примеру четыре бара, или четыре бара, который также может быть описана как четыре атмосфер – это четыре раза атмосферное давление.When engineers calculate the pressure of a fluid inside a vessel, they usually calculate its gauge pressure. This is the pressure differential – the difference in pressure – between the fluid inside the vessel and atmospheric pressure outside. Therefore, with gauge pressure, it is assumed that the atmosphere has a pressure of zero Pascals – even though this is not true. Engineers use gauge pressure because they need to know if a fluid inside a vessel is at higher pressure or at a lower pressure than the outside air (the air in the atmosphere), and if it is, by how much. This allows them to design tanks and pipes so that they do not fail dangerously by exploding if their gauge pressure is positive, or by imploding if their gauge pressure is negative.Pressure can also be measured by comparing it with a vacuum – a void containing no gas or liquid, as in space, where pressure is truly zero Pascals. Pressure compared with a vacuum is called absolute pressure. The absolute pressure of the atmosphere at sea level is approximately 1000.000 Pascals (or 100 kilo-Pascals). Therefore a partial vacuum – which is below atmospheric pressure but is not a perfect vacuum – has a positive pressure when it is measured as an absolute pressure, because it has a higher pressure than a perfect vacuum. But it has a negative pressure when it is measured as a gauge pressure, because it has a lower pressure than the atmosphere. Hydrostatic pressure and siphonic actionIn liquids – most often in water – pressure and flow can be generated by hydrostatic pressure.An example is a water tower which supplies drinking water to homes. Water is stored in the tower at a high level, so that the water pushes down. This is called a head of water. It puts the water at lower level (in the water main) under pressure. If the height of the water tower is increased, this will increase the water pressure at low level. Smaller tanks located at a high level to generate hydrostatic pressure – at the tops of buildings, for example – are called header tanks.