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Throttling When an ideal gas flows through a restrictor, with a constant pressure before and after the restrictor, the temperature remains constant. However, there occurs a pressure drop across the restrictor, through the inner energy transforming into kinematic energy, which is why the temperature falls. However, for real gases this temperature change becomes lasting, even if the gas's energy content is constant. This is called the Joule Thomson effect. The temperature change is equal to the pressure change across the throttling multiplied by the Joule Thomson coefficient. If the flowing medium has a sufficiently low temperature a temperature drop occurs across the restrictor, but if the flow medium is hotter, a temperature increase occurs. This condition is used in several technical applications, for example, in refrigeration technology and the separation of gases.