Oval EL4131, Instruction Manual

Page: 12 / 18

E--883--4N--E
1
7. CALCULATION FORMULAS
7.1 Implementation of Meter Error Correction (Total flow before correction)
Q
1
= a × Ip × (1 + E/100)
where Q
1
: Total flow corrected for meter error ［ l ］
a: Meter factor ［ l/P ］
Ip: Number of input pulses
E: Meter error correction value ［ % ］
The line graph in Fig. 7.1 below shows how meter error curve linearization is achieved. E is
approximate-ly determined by the relationships between input pulse frequency and instrumental
error correction value set at multipoint error points which are programmable along the flowmeter's
instrumental error curve with front-panel keys, and the frequency pulse information (flowrate)
7.2 Implementation of Temperature Correction (Corrected total flow)
Q
2
= Q
1
× K
K = {a + b ・ (t
0
− t) + c ・ (t
0
− t)
2
}
where Q
2
: Total flow corrected for temperature ［ l (normal) ］
Q
1
: Total flow calibrated for meter error ［ l ］
K: Temperature correction factor
t
0
: Reference temperature ［° C ］
ｔ : Line temperature ［° C ］
a thru c: Correction factors
7.3 Instant Flowrate (Uncorrected)
Q
m
= a × f × (1 + E/100) × 3600
where Q
m
: Instant flowrate corrected for meter error ［ l/h ］
f: Input pulse frequency ［ Hz ］
7.4 Instant Flowrate (Corrected)
Q
mc
= Q
m
× K
where Q
mc
: Instant flowrate corrected for temperature ［ l/h (normal) ］
＋
0
−
F
1
F
2
F
3
E
1
E
2
E
3
E
4
F
4
F
8
E
8
E
F
9
｝
9
Fig. 7.1
F
1
thru F
9
Frequency (Hz)
E
1
thru E
9
Meter error correction value (%)
Meter error
Flowrate
(frequency)
Programmable with keys