Heat Engine/Gas Law Apparatus

SKU: TD-8572A Category:



An affordable, general-purpose apparatus for quantitative experiments involving the Ideal Gas Law and for investigations of a working heat engine. Features a nearly friction-free piston/cylinder system. The 32.5 mm diameter graphite piston fits snugly into a precision-ground Pyrex® cylinder so that the system produces almost friction-free motion of 10 cm and minimal leakage.

Measure the actual efficiency of a real heat engine, and bring the concept of P-V diagrams to life.

  • PASCO Heat Engine: Extracts heat from a large hot-water reservoir and does work to lift a weight.
  • Real-time graph: The heat engine cycle is traced on a Pressure vs. Volume graph as the engine goes through each part of its cycle, closing the cycle as waste heat is exhausted to the ice-water reservoir.
  • Heat Engine Efficiency: Students compare the area inside the P-V cycle to the actual work done lifting the weight and see how the efficiency of this heat engine compares to the theoretical maximum.

Typical Applications

  • Investigate Pascal’s Principle
  • Demonstrate a real-time Heat Engine Cycle
  • Charles’ Law Experiment
  • Combined Gas Law (Gay-Lussac’s) Experiment
  • The Mass Lifter Heat Engine Experiment
  • PASCAL’s Principle (using a Small Piston Heat Engine)


  • Air Chamber — Immerse in hot or cold water. All necessary tubing is included
  • Quick-Connect Ports — Two ports connect to the air chamber tubing or to a Low Pressure Sensor
  • Ultra-Low-Friction Graphite Piston
  • Millimeter Scale — Measures piston displacement
  • Locking Screw — Secures piston in any position for fixed volume
  • Mass Platform — Add a mass to do work experiments
  • Precision-bore Pyrex Cylinder — Inside a Protective Plastic Shield
  • Two Port Shut-off Valves
  • Rod Clamp Mount — Mount engine on a rod stand


  • Heat Engine
  • Air Chamber
  • Plastic Tubing with Quick Connect Fittings

How It Works

Heat Engine Doing Work:

When the air chamber is moved from the cold bath to the hot bath, the piston moves up and lifts the 200-gram mass. When the chamber is moved back to the cold bath, external air enters the chamber through a one-way intake valve. Repeating the cycle causes the mass to continue to rise.

Ideal Gas Law:

Place the heat engine on its side so the weight of the piston becomes negligible. Submerge the air chamber in the cold bath and let it equilibrate. Quickly shift the chamber to the hot bath and watch the piston move up the cylinder. The Pressure Sensor shows that the pressure remains constant while the volume increases.


Piston diameter
  • 32.5 mm
Maximum piston displacement
  • ˜10 cm