The Barometer Uses A Basic Design: Closed Test Tube

  •   pressure gauge

      A pressure gauge is a device that measures the pressure (usually atmospheric pressure). Manometers have been in use for hundreds of years and come in a variety of designs, from old glass tubes containing mercury or water to new digital devices.


      Like a pressure gauge, a barometer can also measure atmospheric pressure. In fact, the barometer is a closed pressure gauge. However, barometers are more restricted in design and function than pressure gauges. All barometers are pressure gauges, but not all barometers are barometers.

      Shape and design


      As a subdivision of the Air manometer, the barometer uses a basic design: a closed test tube. Specifically, the traditional barometer is a glass tube with an open end at one end and a vacuum at the other end. At the open end, atmospheric gas exerts pressure on the liquid in the tube. This liquid (usually mercury) will highly match the pressure exerted by the outside gas because the vacuum at the closed end of the tube will not cause a change in the mercury height.

      The closed barometer can be U-shaped or tic-tac-shaped. In a well-shaped barometer, the mercury tube is upside down or placed upside down in larger mercury well, so the closed end in a vacuum is the highest point, while the open end is suspended in the liquid. Then, the external air presses down the mercury hole, and the mercury expands into the closed tube.

      Nowadays, barometers can also be digital or aneroid barometers, which makes them easy to carry-traditional glass barometers need to be installed on a table or standstill. As you can see in a car, an aneroid barometer may have a digital or clock interface. These barometers have a series of air-filled cells that arise in response to atmospheric pressure. This will pull the lever connected to the battery, thereby changing the dial on the barometer interface.

      pressure gauge

      The pressure gauge can be open, closed, or digital. The open pressure gauge is filled with liquids such as water or mercury, and the tube is U-shaped. The two tops of the U-shaped tube can be exposed so that the atmosphere can apply pressure to each side. The open pressure gauge does not need to have the same size as the tube arm, and can even have a well at one end.

      In addition to simple U-shaped open pressure gauges, many pressure gauges also have a bulb or other accessories at one end, which is filled with high-pressure gas. This gas exerts pressure on one end of the tube, while the atmosphere at the other end exerts the same pressure. The pressure gauge can therefore measure different kinds of air pressure.

      Another more accurate type of pressure gauge is the inclined tube pressure gauge. This is an open pressure gauge, usually inclined at a 1-inch vertical rise position, with a hole at the lower end. The tilt angle can measure low pressure more accurately.

      In a closed pressure gauge, one end of the pressure gauge is connected to high-pressure gas, and the other end has a vacuum state, rather than being open to the air. The barometer also has this function, but it can only measure gases in the atmosphere.

      Inner fluid


      Barometers are usually filled with mercury. Heavy liquids are required, or the barometer must be high to show relatively large changes in atmospheric pressure. In digital or aneroid barometers, there is no liquid-instead there are air chambers.

      pressure gauge

      Like barometers, glass manometers are usually filled with mercury or other heavy liquids. However, open pressure gauges can also be filled with lighter liquids, which have smaller pressure changes. These liquids include water, oil, bromide, and benzene. Using water or oil can solve the problem of mercury poisonings, such as poisoning and toxicity.