This part of ISO 10816 gives criteria for assessing vibration levels when measurements are made in situ. The criteria specified apply to machine sets having a power above 15 kW and operating speeds between 120 r/min and 15 000 r/min. The machine sets covered by this part of ISO 10816 include: — steam turbines with power up to 50 MW; — steam turbine sets with power greater than 50 MW and speeds below 1 500 r/min or above 3 600 r/min (not included in ISO 10816-2); — rotary compressors; — industrial gas turbines with power up to 3 MW; — generators; — electrical motors of any type; — blowers or fans. NOTE However, the vibration criteria presented in this part of ISO 10816 are generally only applicable to fans with power ratings greater than 300 kW or fans which are not flexibly supported. As and when circumstances permit, recommendations for other types of fans, including those with lightweight sheet metal construction, will be prepared. Until such time, classifications can be agreed between the manufacturer and the customer, using results of previous operational experience, see also ISO 14694[4]. The following are excluded from this part of ISO 10816: — land-based steam turbine generator sets with power greater than 50 MW and speeds of 1 500 r/min, 1 800 r/min, 3 000 r/min or 3 600 r/min (see ISO 10816-2); — gas turbine sets with power greater than 3 MW (see ISO 10816-4); — machine sets in hydraulic power generating and pumping plants (see ISO 10816-5); — machines coupled to reciprocating machines (see ISO 10816-6); — rotodynamic pumps including integrated electric motors, i.e. where the impeller is mounted directly on the motor shaft or is rigidly attached to it (see ISO 10816-7); — rotary positive displacement compressors (e. g. screw compressors); — reciprocating compressors; — reciprocating pumps; — submerged motor-pumps; — wind turbines. The criteria of this part of ISO 10816 apply to in situ broad-band vibration measurements taken on the bearings, bearing pedestals, or housing of machines under steady-state operating conditions within the nominal operating speed range. They relate to both acceptance testing and operational monitoring. The evaluation criteria of this part of ISO 10816 are designed to apply to both continuous and non-continuous monitoring situations. This part of ISO 10816 encompasses machines which may have gears or rolling element bearings, but does not address the diagnostic evaluation of the condition of those gears or bearings. The criteria are applicable only for the vibration produced by the machine set itself and not for vibration which is transmitted to the machine set from external sources.