Yokogawa 415 Steam and Gas - Manual (Page 31)

PROGRAMMING THE FLOW COMPUTER
For equations 11 to 18 to work, a number of parameters need to be
programmed. These include:
K
F
K-factor (for frequency producing flowmeters).
S
M
Span (for analog flowmeters).
ν
B
Base specific weight at which the span is determined.
The flowmeter will measure the flow input A (normalised between 0
and 1) and the temperature T
F
and pressure P
F
. The temperature and
pressure are used to calculate the specific weight,
ν
, and enthalpy, h,
from internal equations. Other parameters must also be programmed
and these are fully detailed in section 5.
Example 7
A vortex flowmeter has a K-factor of 68.32 pulses/ft
3
, and it is
required to measure saturated steam in lbs/hour. What are the
main parameters to be programmed?
The instrument should be programmed for steam measurement
from a frequency meter. Because the steam is saturated, it is only
necessary to use either a temperature or pressure sensor. Because
of cost, a temperature probe is used. The main parameters to
program are simply:
Units US Units
K-factor = 68.32
Timebase hours
Operation 29