The pressure in a natural gas pipeline (Methane) is measured by the manometer shown with one of the legs open to the atmosphere where the local atmospheric pressure is 14.2 psi a. Determine the absolute pressure in the pipeline when pressure changes in the gases is neglected. Use SG=13.6for mercury as shown in the figure. Clearly list approximations used. (Ans: 18.1 psia) Discussion: Determine the change in pressure through the natural gas and air regions. (See Tables A-9E and A-10E for properties of air and methane at one atmosphere. Assume a temperature of 50°F and use the ideal gas law to find the density at the actual pressure of the air and methane in this problem) Can the change in pressures through the gases be neglected?

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