Yokogawa 415 Steam and Gas - Manual (Page 28)

3.3 STEAM MEASUREMENT
The Model 415 incorporates equations to handle both saturated and superheated
steam over the following range:
Pressure 0 kPa abs (0 psia) to 100,000 kPa abs (10,000 psia)
Temperature 100°C (212°F) to 800°C (1472°F).
When measuring saturated steam, it is possible to delete either the pressure or
temperature sensor since, on the saturation line, there is a corresponding pressure
for all temperatures. For superheated steam, it is necessary to use both the
pressure and temperature sensors.
Both the mass flow (in kg/hr or lbs/hr) and the heat content (enthalpy) are
calculated internally based on the 1967 IFC Formulation (ASME) Equations.
The equations use the pressure and temperature readings to determine:
-
ν
, the specific volume of steam in dm
3
/kg or,
- h, the specific enthalpy of steam in kJ/kg.
A. Volumetric Flowmeters With Frequency Output.
eg. Vortex, Steam turbines, etc.
Mass Flow
......(11) SI Units : Q
M(SI)
= 1000 .
N. frequency (Hz)
K
F
.
1
ν
F
......(12) US Units : Q
M(US)
= 62.435 .
N. frequency
K
F
.
1
ν
F
(Note: for US units K
F
is in pulses/ft
3
.)
26 Operation