Work done by a piston can be defined as pressure multiplied by a change in volum

Question

Work done by a piston can be defined as pressure multiplied by a change in volume (W = P Delta V). Calculate work in Joule (J) for a piston that expands from 20 L to 40 L at a constant pressure of 150 psi. You walk by a pressurized vessel that is filled with toxic gas. The vessel has a rated bursting pressure of 1000 psia. The gauge on the vessel measures 68 bar. Are you in danger? A manometer (see figure) is installed to measure the pressure drop (Delta P) between two points (P_1 and P_2) in an HVAC duct The capillary column is filled with a hydrocarbon-based liquid and angled 30 degree from the horizontal plane. If the readout of the manometer is 20 mmH_2O equivalents, what is the pressure drop across the duct in terms of Pascals (Pa)?

Explanation / Answer

1) Work done = P deltaV

P = 150 psi = 1.034 x 10^6 Pa

Vi = 20 x 10^-3 m^3

Vf = 40 x 10^-3 m^3

Work done = 1.034 x 10^6 ( 40x10^-3 - 20x10^-3)

= 20680 J

2) Gauge pressure = inside pressure - outside pressure

and 1bar = 14.50Psi and atmos[pheric pressure = 14.69 psi
68 x 14.50 Psi = Pi - 14.69Psi

Pi = 1000.69 Psi

and rates pressure us 1000 psi.

so Yes, you in danger.

Please don't post many questions in 1 link.

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