Tämä tapahtuu ottamalla pieni osa laimennusilmasta, jonka virtausnopeus on jo mitattu virtauksen mittauslaitteella FM1, ja syöttämällä se TT:hen paineilma-aukon avulla. ###>This is done by taking a small fraction of the dilution air whose flow rate has already been measured with the flow measurement device FM1, and feeding it to TT by means of a pneumatic orifice.