Yokogawa digitalYEWFLO (DY) - Manual (Page 53)

<6. PARAMETERS>
6-17
IM 01F06A00-01EN
(7) Item H (ADJUST)
This item for setting of adjustment.
NOTE
In case that Reynolds adjustment (H25), Gas
expansion correction (H30) or select a break
point correction (H40) is necessary to set,
D10: LOW CUT must be set after the items
for compensations (H25, H30, H40) are set to
“ACTIVE”.
[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 fl owrate.
[H25:REYNOLDS ADJ] Reynolds
adjustment
Select the Reynolds adjustment.
This adjustment should be done in case of their
error compensation, because error of vortex
fl owmeter should be increased when it come to low
reynolds numbers.
NOT ACTIVE(0): Not correction calculation
ACTIVE(1): Correction calculation
The following item should be set in case of
which “H25” is “ACTIVE”.
[H26:DENSITY f] Density at operating
condition
Set the density at operating condition.
[H27:VISCOSITY] Viscosity at standard
condition
Set the value of viscosity at standard conditions.
The values should be used for Reynolds
adjustment.
Reynolds number(Re) is calculated as shown in the
formula below.
Re = 354 ×
Q  
f
D  μ
Q : Volumetric fl ow (m 3 /h)
D : Internal diameter (mm)

f
: Density at operating condition
μ : Viscosity (m Pa · s (cp))
Flowrate error of vortex fl owmeter increases as
Reynolds number decrease less than 20000.
By setting H25, H26, H27, it corrects the error.
[H30:EXPANSION FA] Gas expansion
correction.
When measuring a compressibility gas by mass
fl ow (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 to H50] Instrumental Error Correction
 Correct the instrumental error in fl owmeter
characteristics using 1 line-segment
approximation (with fi ve 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 fl ow input of f
1
or less is present,
correct the instrumental error as the corrected
value=d
1
.
(3) When a fl ow 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.
Set value = -
Q
s
-I
100
I
Where
Q
s
: Correct fl owrate determined by a reference
apparatus
I : Indication of vortex fl owmeter