The Length Expansion Tool PHT 321 is used to accurately measure the expansion coefficient of a material. In this kit, there are three test pipes made of aluminum, copper and brass. Each pipe is equipped with a thermistor to measure pipe temperature during the steam heat generated by the steam generator. The length additional of the pipe is measure using a dial indicator in precision of 0.01 mm.

A set of this tool consists of three test pipes, a steam generator, a digital multimeter and a hose.