Liquid chlorine has a very high coefficient of thermal expansion. Relatively small increases in liquid chlorine temperature can create enough pressure to cause a blocked-in section of piping to rupture or leak at the connections. A temperature rise from 14°F (-10°C) to 32°F (0°C), will expand liquid chlorine by 2%. However, in a contained volume, the same temperature rise will increase the hydraulic pressure by more than 2400 psi.
Users shall have means to prevent trapping liquid between valves. One or more of the following options may be implemented: