Apiston–cylinder device initially contains 2 kg of refrigerant-134a at 800 kpa and 84°c. at this state, the piston is touching on a pair of stops at the top. the mass of the piston is such that a 500-kpa pressure is required to move it. a valve at the bottom of the cylinder is opened, and r-134a is withdrawn from the cylinder. after a while, the piston is observed to move and the valve is closed when half of the refrigerant is withdrawn from the cylinder and the temperature in the tank drops to 20°c. the properties of r-134a at various states are v1 = 0.033172 m3/kg, u1 = 294.504 kj/kg, h1 = 321.042 kj/kg, v2 = 0.042115 m3/kg, u2 = 242.42 kj/kg, and h2 = 263.48 kj/kg.