This Code provides directions and rules for the conducting and reporting of performance tests on single or multi-stage ejector units. The primary object of the test measurements described herein is to establish: (a) Ejector capacity in relation to suction pressure; (b) Discharge pressure in relation to suction pressure; (c) The flow rate of the motive fluid in relation to a stipulated pressure and temperature; and (d) Ejector stability; i.e. the relation of motive fluid pressure or the discharge pressure to breakdown and recovery of the pumping action. The rules and procedures of PTC 24 are intended primarily for the test of ejectors in which the motive fluid is steam. They may be used, however, with any motive fluid for which the physical properties are completely and reliably known. The instructions and capacity measurements provide for tests where the suction fluid pumped is air, water vapor, or other gases for which the physical and thermodynamic properties are known. A procedure is provided for tests on gas mixtures in which the components can be separately measured and controlled. If the motive fluid is steam or other condensable vapor, it must be dry (without any moisture).