The measurement of flow of the mixture of chlorine and nitrogen into a process and using a ratio of chlorine to the total mixture into a process, is discussed. The use of mass flowmeters require the integration of readings for a time equaling the displacement of the mixer. The chlorine flowmeter may well be operating in a region where the compressibility is varying rapidly with P&T. For the mixture stream, computation of a mass flow from temperature and pressure presumes the molecular weight of the mixture is known. If precise control of chlorine concentration is required, photometric analyzers could be used to monitor the chlorine concentration in the mixed gas in similar applications. For HART, Foundation fieldbus, or Profibus PA, software tag is set and the calibration on the bench is checked for any device regardless of protocol. The Fieldbus Foundation does a device-testing policy.
