5-15
IM 01F06A00-01E
5. PARAMETER SETUP
(7)
Item H (ADJUST)
This item for setting of adjustment.
NOTE
In case that item H (ADJUST) and D10: LOW CUT
are necessary to set, change all appropriate
parameters of item H before setting D10.
[H10, H11:TRIM 4mA, TRIM 20mA] Triming of
4mA and 20mA
Fine tuning adjustment of 4mA and 20mA output.
Fine tuning range is form -1.00% to 1.00%.
[H20:USER ADJUST] Conversion factor for
user setting.
Set conversion factor by user.
This conversion factor is converted into measurement
flowrate.
[H25:REYNOLDS ADJ] Reynolds adjustment
Select the Reynolds adjustment.
This adjustment should be done in case of their error
compensation, because error of vortex flowmeter should be
increased when it come to low reynolds numbers.
The following item should be done in case of
which “H25” is “ACTIVE”.
[H26:DENSITY f]
Set the density at operating condition.
[H27:VISCOSITY]
Set the value of density and viscosity at standard conditions.
These values should be used for Reynolds adjustment.
Reynolds number(Re) is calculated as shown in the formula
below.
Q
·
ρ
f
Re = 354
×
D
·
v
Q : Volumetric flow (m
3
/h)
D : Internal diameter (m)
ρ
f : Density at operating condition
µ
: Viscosity (m Pa · s (cp))
Flowrate error of vortex flowmeter increases as Reynolds
number decrease less than 20000.
By setting H25, H26, H27, it corrects the error.
[H30:EXPANSION FA] Gas expansion correc-
tion.
When measuring a compressibility gas by mass flow (Steam
M, Gas M) and standard condition (Gas Qn), this expansion
factor is useful to correct the deviation from the ideal gas
law.
[H40:FLOW ADJUST] Select a break point
correction
Select a break point correction for the instrumental error from
“NOT ACTIVE(0) OR ACTIVE(1)”.
[H41, H45:FLOW ADJUST] Instrumental Error
Correction
■
Correct the instrumental error in flowmeter characteristics
using 1 line-segment approximation (with five correction
factors).
(1) Flow frequency input at line segments needs to be
f
1
≤
f
2
≤
f
3
≤
f
4
≤
f
5
.
When four correction factors are available, line segments
need to be f
4
=f
5
and d
4
=d
5
.
When three correction factors are available, line
segments need to be f
3
=f
4
=f
5
and d
3
=d
4
=d
5
.
(2) When a flow input of f
1
or less is present, correct the
instrumental error as the corrected value=d
1
.
(3) When a flow input of f
5
or more is present, correct the
instrumental error as the corrected value=d
5
.
(4) Abscissa (f
1
to f
5
) : Set the break-point frequencies as
parameters.
(5) Ordinate (d
1
to d
5
) : Set the corrected value (%) at each
break-point as parameters.
Qs-I
Set value = -
×
100
I
Where
Qs :
Correct flowrate determined by a reference
apparatus
I :
Indication of vortex flowmeter
• Definition of error varies with the type of flowmeter. Be
careful of the difference in signs in the error and corrected
value.
f(Hz)
Qf =
×
100
K-factor
holds and the error is included in the K-factor.
Therefore, for the region where the K-factor shift on the
positive side, the corrected value is negative.
The corrected value when the calibration fluid of the
flowmeter and the fluid to be measured are different must
be set as a corrected value obtained by making both
abscissas agree with respect to the Reynolds number.
