• Demonstrating the laws of state changes in gases experimentally.
  • Isothermic change of state, Boyle-Mariotte Law.
  • Isochoric change of state, Gay-Lussac’s Law.



  • Experimental investigation of gas laws
  • Transparent measuring vessel 1 for investigation of isothermic change of state.
  • Hydraulic oil filling for changing volume of test gas.
  • Built-in pump ensures necessary pressure differences to move the oil volume.
  • Pump can also be used as vacuum pump.
  • 5/2-way valve for switching between compression and expansion.
  • Transparent measuring vessel 2 for investigation of isochoric change of state.
  • Electrical heater with temperature control in vessel 2
  • Sensors for temperatures and pressures.

Knowledge of the gas laws is a fundamental requirement of any training course of in thermodynamics. The unit Change of State of Gases enables the students to study two changes of state of gases experimentally. Boyle’sLaw deals isothermic (Constant temperature) change of state on the other hand Gay-Lussac’s Law deals isochoric (Constant Pressure) change of state. Air is used as a test gas and state of change is observed through two transparent vessels.

Familiarization with the gas laws is a fundamental requirement of any training course in thermodynamics.

The apparatus enables two changes of state to be studied experimentally: Isothermic change of state, also known as the Boyle-Mariotte Law, and isochoric change of state, which occurs at a constant volume. Transparent vessels enable the change of state to be observed. Air is used as the test gas.

In vessel 1, positioned on the left, the enclosed air volume is reduced or increased using a pump and hydraulic oil. This results in an isothermic change of state. The pump can also operate as a vacuum pump. If the changes occur slowly, the change of state takes place at an almost constant temperature.

In vessel 2, positioned on the right, the temperature of the test gas is increased by a controlled electric heater and the resulting pressure rise is measured. The volume of the enclosed gas remains constant.

Temperature is measured electronically & pressure is measured through pressure gauge.

Software TH-3103SW (optional)
DAQ software specially designed in National Instrument™, LABVIEW™ environment to measure and calculate the results of apparatus. While using software a set of electronic sensors are included. Software can be run with any Windows™ environment.