Problem 1.2 - Using two manometers to measure pressure drop and downstream pressure of compressed air flowing in a pipe

A Throttling Valve is often used to control the downstream pressure of a high pressure fluid (such as steam or air) flowing in a pipe. In the following diagram we have a water manometer to measure the pressure drop ΔP caused by the throttling valve as well as a mercury manometer to measure the downstream pressure of the air.

If the height difference in the water manometer hw is 150 cm, and that in the mercury manometer hHg is 225 cm, determine a) the pressure difference ΔP [14.7 kPa] and b) the downstream absolute pressure of the air P2 [400 kPa]. Assume that the density of water is 1000 kg/m3, the density of mercury is 13,600 kg/m3, and that the atmospheric pressure is 100 kPa.


Engineering Thermodynamics by Israel Urieli is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License