Siemens SITRANS FX300, Operating Instructions Manual, Page: 14 / 80

2
DEVICE DESCRIPTION
14
SITRANS FX300
www.siemens.com/flow 06/2009 - SFIDK.PS.050.F2.02 A5E02100423
2.2.5 Gross heat meter
In almost all applications with saturated steam, the steam is used for heating. It is much more
interesting to know how great the heat flow volume is that is available to the process, than to
know how great the flow is in kg/h.
As the enthalpy of steam changes with the temperature, it cannot be assumed to be constant.
The vortex flowmeter has a special feature which calculates the flow of steam and water as
power. The enthalpy tables are permanently programmed into the memory of the device.
The online density-compensated mass flow is multiplied by the correct enthalpy to obtain the
flow as power output.
Power {Q
H
] = mass flow [Q
m
] x enthalpy [H]
If the gross heat meter is activated, both the totalizer for the absolute steam consumption as
well as that for the energy run internally.
MA_Siemens_Sitrans_FX300_R02_en_PRT.book Page 14 Monday, June 22, 2009 8:17 AM