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▷ Once the required minimum testing time has
been reached, the measurement can be termi-
nated – marker 4.
4 Briefly press the selection key
the measurement.
▷ Measurement on the unit under test stops au-
tomatically once the full number of measuring
unit revolutions has been completed – marker 5.
▷ A beep acknowledges the end of the measure-
ment.
▷ Measurement is terminated automatically after
5 hours.
5 Stop the test on the master meter – marker 6.
▷ The measurements are then available.
6 Read off the flow rate on the master meter or
calculate if necessary:
a) taking into account the inherent error of the
master meter:
Q
= V
x 3600 s/h / ((1+F
act,N
N
b) If the inherent error of the master meter has
already been taken into account in the dis-
played volume (V
Q
= V
x 3600 s/h / Δt
act,N
act,N
7 Calculate the flow rate on the unit under test:
Q
= V
/Δt
P
P
P
for BK-G...ET, the following applies: V
8 The accuracy is checked by comparing the flow
rates. The pressure and temperature values of
the unit under test corrected with reference to
the master meter have already been taken into
account here:
F
= 100% x (((Q
x p
P
P
The following applies:
p
= relevant absolute pressure on the unit under
P
test
The following also applies:
for BK-G...E: T
= (273.15 + {t
P
where t
= relevant gas temperature on the unit
g
under test in °C (display)
for BK-G...ET: T
= (273.15 + {t
P
where t
= 15°C (see page 15 (Technical data)):
b
T
= 288.15 K
P
for BK-G...ETe:
If Q
in step 7 is determined from the converted
P
volume V
, the following applies:
b
T
= (273.15 + {t
}) K (t
P
b
cal data))
If Q
in step 7 is determined from the non-con-
P
verted volume V
, the following applies:
P
T
= (273.15 + {t
}) K
P
g
where t
= relevant gas temperature on the unit
g
under test in °C (display)
▷ The curly brackets mean "numerical value of".
▷ On a nozzle test rig with a known flow rate,
steps and 6 can be omitted.
▷ The error calculation is based on PTB Testing
Instructions, Volume 29: "Messgeräte für Gas –
Gaszähler" (Measuring instruments for gas – gas
meters), Edition 2003.
in order to end
/100) x Δt
N
= V
):
N
act,N
N
= V
P
b15
x T
) / (Q
x p
x T
)) - 1)
P
N
act,N
N
P
}) K
g
}) K
b
see page 15 (Techni-
b
Option : cyclic test with a given volume
Test load and minimum test volumes for the test with
index readout:
Q
max
Type
in
m
3
/h
BK-G1.6
2.5
BK-G2.5
4.0
BK-G4
6.0
BK-G2.5
4.0
BK-G4
6.0
BK-G6
10
BK-G6
10
BK-G6
10
BK-G10
16
BK-G16
25
BK-G25
40
Master meter test procedure
)
N
V
N
8
7
9
To activate the cyclic test on the unit under test,
briefly press the selection key
marker 7. The index will thus be "armed" for
measurement.
Start the test on the master meter – marker 8.
▷ As soon as one of the significant sensor posi-
tions has been detected, the unit changes to
measuring mode – marker 9.
Test is ended – marker 10.
4 Read off the test results on the unit under test.
▷ The measured values are updated with each 1/8
revolution of the measuring unit.
5 Compare the measurement results with the mas-
ter meter and determine the measuring deviation
on the unit under test:
a) taking into account the inherent error of the
master meter:
F
= 100% x (((V
P
(V
b) If the inherent error of the master meter has al-
ready been taken into account in the displayed
volume (V
F
= 100% x (((V
P
T
P
▷ The following applies: p
pressure on the unit under test
GB-11
Cyclic
Test volume in dm
volume
Q
0.2 Q
min
in dm
3
1.2
36
72
1.2
36
72
1.2
36
72
2
60
120
2
60
120
2
60
120
4
120
240
6
180
360
6
180
360
6
180
360
12
360
720
on the index –
x (1+F
/100) x p
P
N
x p
x T
)) - 1)
N
N
P
= V
), the following applies:
N
act,N
x p
x T
) / (V
P
P
N
)) - 1)
= relevant absolute
P
3
at
Q
max
max
72
72
72
120
120
120
240
360
360
360
720
10
11
x T
) /
P
N
x p
x
act,N
N
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