In streaming open-circuit systems, such as reactors or pipelines, and agitated closed-circuit systems, such as mixer-settlers or motor-driven combustion chambers, the work or work output (the operating sequence) is an important partial problem. Formulations, such as ＇＇the work transported into the individual system is converted irreversibly into thermal energy＇＇ are used (1). If the processes taking place are separated consequently in favour of the balance equations (2) in accumulators, transport and conversion processes, it will be possible to differentiate the above statement more precisely: Then the first process, which exceeds with the flow system boundary, is the transport of mechanical (kinetic and/or pressure-volume) energy E(pV) by the force of pressure F-p = A(p) p. The second process is the work transport, which is caused vertically to the flow, by the frictional force F-tau = A(tau) tau, which in general integrally considered does not occur. These work transports are not interrelated with the entropy transport (or irreversible entropy conversion (production)) as is the case with heat transport. Only the third energy conversion process in volume, which transforms kinetic energy into thermal energy, creates entropy production. The essay explains these interrelations.