Pressure

Similarly, the refrigeration service expert must measure the vital functions of the system to diagnose the condition and to solve any problems that exist. Pressure is the primary vital sign of a mechanical refrigeration operating system. It provides important information for the evaluation of the system, charging with refrigerant and checking it to work properly with the full or partial load. Pressure is used with the temperature readings permit you to troubleshoot a system.

Pressure is the force per unit area. Pounds per square inch, or PSI, this is one of the ways of expressing pressure. Pound is a unit of power, while the square inch unit area. An everyday example of pressure shown here, filling in a 1-foot cube with water. When filled to the brim, Cuba takes approximately 8 litres of water, which weighs about 64 kilograms. The total force that the bottom of the cube has on the top of the table 64 kilograms. Pressure, however, is the total force (64 kilograms) divided by the area of the bottom of the cube (12 in. x 12 century. = 144 sq. century). This means that the pressure on the surface of the table, 64 pounds divided by 144 square inches or 0.44 PSI.

Pressure behaves differently for solids, than for liquids or gases. In solids, pressure, tend to exert themselves only in one direction. When weightlifter raises the bar, it works against the pressure exerted down straight by the weight that solid.

Liquid, on the other hand, tend to exert pressure evenly in all directions. The air over the water is a liquid, because it is gas. A man in a boat is the pressure of a liquid we call "air", by clicking on it from all sides. He does not feel it, because he used to live with this pressure and because it is relevant equally throughout the body. Swimmer also has the pressure of the liquid (water) all around him. The deeper it sinks, the more water will be "stacked" on top of him, and the more pressure will be exerted on his body. Swimmer will feel the pressure varies with depth. As this pressure more than the air, he could feel it pressing on his diving mask and ear.

We used to live in a fluid, the pressure on our bodies in the Earth's atmosphere. We are so unaware of it, that we tend to think that there is no pressure there. It seems that the air around us weightless, but in reality he have 14.7 pounds per square inch of pressure around the body at sea level.

Pressure, weight of our atmosphere has on us (and everything on the Earth's surface) is called atmospheric pressure. This pressure cannot be measured by a scale, because there's just so much under the pressure scale to the platform over him. The same principle holds true for the measurement of the pressure caused by water or other liquids.

Barometer measures the atmospheric pressure. Therefore, the atmospheric pressure is also called barometric pressure. Mercury barometer tube, as shown below, has a tube which has all of atmospheric air are removed. It closed and open end sits in a vessel with mercury. Barometer compares the pressure of the atmosphere pressure is no atmosphere...