Why ISO 7919 Is Important For Vibration Measurement Engineers?

The main target of condition monitoring and machinery protection systems is to ensure the health and continuous operation of the plant machinery. In this regard vibration measurement systems along with vibration transducers are installed for continuous measurement and analysis of machine vibrations. To this end users need a reference to compare machine vibration with it to evaluate the state of each machine. ISO 7919 provides a reference like allowable vibrations and alarm or trip conditions for various machinery based on some statistical analysis of historical data gathered by ISO TC 108.

ISO7919-2

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Large Steam Turbine

ISO 7919-2 gives guidelines for applying evaluation criteria for shaft vibration under normal operating conditions, measured at or close to the bearings of steam turbine generator sets. These guidelines are presented in terms of both steady running vibration and any magnitude changes which may occur in these steady values. In general, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration. This part of ISO 7919 applies to large land-based steam turbine generator sets for power stations, having rated speeds in the range 1 500 r/min to 3 600 r/min, and power outputs greater than 50 MW.

ISO7919-3

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General Critical Machines

ISO 7919-3 gives guidelines for applying evaluation criteria for shaft vibration under normal operating conditions, measured at or close to the bearings of coupled industrial machines. These guidelines are presented in terms of both steady running vibration and any magnitude changes which may occur in these steady values. The numerical values specified are not intended to serve as the only basis for vibration evaluation since, in general, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration. ISO 7919-3 applies to coupled industrial machines with fluid-film bearings, having maximum continuous rated speeds in the range 1 000 r/min to 30 000 r/min, and not limited by size and power, comprising: — steam turbines — turbo compressors — turbo pumps — turbo generators; — turbofans — electric drives and associated gears, where relevant.

ISO7919-4

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Gas Turbine

ISO 7919-4 gives guidelines for applying evaluation criteria for shaft vibration under normal operating conditions, measured at or close to the bearings of gas turbine sets. The numerical values specified are not intended to serve as the only basis for vibration evaluation since, in general, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration. It applies to all gas turbine sets (including those with gears) with fluid-film bearings, outputs greater than 3 MW and shaft rotational frequencies from 3 000 r/min to 30 000 r/min. Aircraft derivative engines are excluded. Depending on the construction and mode of operation, there are three principle groupings of gas turbine sets:

  • Single-shaft constant-speed gas turbine sets;
  • Single-shaft variable-speed gas turbine sets;
  • Gas turbine sets with separate shafts for hot gas generation and power delivery.

ISO7919-5

Hydro Turbine

ISO 7919-5 gives guidelines for applying shaft vibration evaluation criteria, under normal operating conditions, measured at or close to the bearings of machines or machine sets in hydraulic power generating and pumping plants. The numerical values specified are not intended to serve as the only basis for vibration evaluation since, in general, the vibratory condition of a machine is assessed by consideration of both the shaft vibration and the associated structural vibration.

It applies to machines or machine sets in hydraulic power generating and pumping plants where the hydraulic machines have speeds from 60 r/min to 1 800 r/min, shell- or shoe-type sleeve bearings, and main engine power of at least 1 MW. The position of the shaft line may be vertical, horizontal or at an arbitrary angle between these two directions.

Machine sets covered by this part of ISO 7919 may be a combination of hydraulic turbines and generators,  pumps and electrical machines operating as motors, pump-turbines and motor-generators, including auxiliary equipment (e.g. starting turbines or exciters lying in the shaft line). This part of ISO 7919 is also applicable to turbines or pumps connected to generators or electrical motors via gears and/or radially flexible couplings.
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