Bronkhorst®
Instruction Manual EL-FLOW® Classic series
9.17.085D
10
2.9
Zeroing before use
The zero-point of each instrument is factory adjusted at approximately 20 °C and atmospheric pressure. If the operating
conditions differ significantly from the ambient conditions used for factory adjustment, the zero point may need to be re-
adjusted.
Procedure for zeroing with the multifunctional switch on top of the instrument:
·
Warm-up the instrument, pressurize the system and fill the instrument according to the process conditions.
·
Make sure no flow is going through the instrument by closing valves near the instrument.
·
The setpoint must be zero.
·
Press and hold the multifunctional switch. After a short time the red LED will go ON and OFF, then the green LED will go
ON. At that moment release the switch.
·
The zeroing procedure will start at that moment and the green LED will blink fast. The zeroing procedure waits for a
stable signal and saves the zero. If the signal is not stable, zeroing might take longer and the nearest point to zero is
accepted. The procedure will take approximately 10 seconds.
·
When the indication is showing 0% signal and the green indication LED is glowing continuously again, then the zeroing
action was successful.
2.10
Calibration
EL-FLOW® Classic
instruments are Air or N
2
calibrated. Bronkhorst High-Tech B.V. certifies that all instruments meet the rated
accuracy. They have been calibrated using measurement standards traceable to the standards of the Dutch Metrology
Institute (VSL).
The calibration is converted to the customer’s gas and conditions using a detailed conversion model. This conversion adds
a level of calibration uncertainty.
Rule of thumb for calculating the conversion uncertainty:
Uncertainty < 2% x CF
for CF > 1
Uncertainty < 2% / CF
for CF < 1
With CF defined as the approximate conversion factor, which can be calculated with:
in which:
C
pn
specific heat
r
n
density at normal conditions
(1)
calibration fluid (Air or N
2
)
(2)
customer fluid
EL-FLOW® Classic
instruments are delivered with a statement of compliance. This
document can be found at
http://www.bronkhorst.com/en/qrclassic
.
Use the hyperlink above or scan the QR-code on the right or on top of the instrument.
