Calculation a lifetime of a beam practically never coincides with the measured values. An interesting problem is the analysis of the experimental decay rate of the beam plot depending on a current of the beam. At normal work of the storage ring a lifetime is limited by scattering on residual gas and intrabeam scattering or Touschek effect. The decay rate can be written as a term due to the Touschek effect; other term due to the current dependent pressure induced by the gas desorption under the synchrotron radiation being proportional to the beam current and third one due to the residual gas pressure. The decay rate plot against the stored current consists of separable components as mentioned above.
         It is shown a typical example of decay rate plot and components due to gas desorption, residual gas and the Touschek effect.