A comparison of several measuring methods for flow rate of air leaking into condenser and vacuum system has been carried out

the advantages and disadvantages of each method and feasibility of its implementation in the field being analysed

and a new method for measuring flow rate of air leaking into condenser and vacuum system being created.The new mthod has been practically used on 300 MW units

obtaining better results.The new method solved the problems of measuring the flow rate for leaking-in air and that of extracting air in the air-extracting equipment at the field of units' practical operation

laying a foundation for studying the influence of air upon the performace of condenser and of the air-extracting equipment

and providing with a new idea for testing the performace of air-extracting equipment at the field.