Liquid Controls SP4000 - Manual (Page 68)

65
SP4000 Flow Computer
2
RATE 1
TOTAL
Enter the maximum possible frequency of a flowmeter with a digital
output. Using the value entered here, the flow computer selects a
suitable limiting frequency for low pass filter to help suppress
interference from higher frequency signals.
Input:
Max. 5 digit number: 10...40000 (Hz):
Display: 40000 Hz
LOW PASS FILTER
LOW PASS
FILTER
DP FACTOR
(Continued) The DP-Factor (K
DP
) is then computed using one of the following
equations:
Steam:
Liquid:
Gas:
K
DP
DP-Factor
M Mass flow
Q Volumetric flow
Q
REF
Corrected volumetric flow
ε
1
Gas expansion factor
T Operating temperature
T
CAL
Calibration temperature
∆
p Differential pressure
ρ
Density at flowing conditions
ρ
REF
Reference density
Note:
The computation accuracy can be enhanced by entering up to 16
values for Reynold's Number DP-Factor in a linearization table (see
"LINEARIZATION"). Each DP-Factor can be calculated using the
above procedure. For every calculation, a sizing sheet is required.
The results have to be entered in the linearization table afterwards.
Q
REF
•
ρ
REF
• (1 – K
ME
• (T – T
CAL
))
ε
1
•
√
2 •
∆
p •
ρ
K
DP
=
Q • (1 – K
ME
• (T – T
CAL
))
2 •
∆
p
ρ
K
DP
=
M • (1 – K
ME
• (T – T
CAL
))
ε
1
•
√
2 •
∆
p •
ρ
K
DP
=
6.8
FLOW INPUT
(Continued)
FLOW INPUT