Abstract: A test system for use in testing Aircraft Rescue Fire Fighting and Structl Pumper vehicles equipped with fire fighting foam distribution systems. The dye piping arrangement for the test system uses a dye concentrate and water mixture which are delivered into the dye water foam free test system through a three way ball valve, a proportioner and eductor. Fluid flow through the eductor generates a vacuum or negative pressure within the eductor. The dye concentrate from a dye storage bottle is then suctioned into the foam distribution system by the negative pressure within the eductor. A needle valve, check valve and a dye solenoid valve are included in the system. The needle valve meters the amount of dye suctioned into the dye water foam distribution system. The check valve prevents any fluids from back flowing into the dye concentrate tank. The normally closed dye solenoid valve is remotely operated by an ON-POWER OFF-OFF three position switch.