Omega FMA1700A, Руководство пользователя, Страница: 17 / 40

This practice is recommended when a reference gas is found with thermodynam-
ic properties similar to the actual gas under consideration. The appropriate rela-
tive correction factor should be recalculated - see section 9. It is standard practice
to calibrate Mass Flow Meters with dry nitrogen gas at 70
F
F (21.1
F
C), 20 psig
(1.4 bars) inlet pressure and 0 psig (0 bar) outlet pressure. It is best to calibrate
the FMA1700A/1800A transducers to actual operating conditions. Specific gas
calibrations of non-toxic and non-corrosive gases are available at specific condi-
tions. Please contact your OMEGA
7
for a price quotation. It is recommended that
a flow calibrator of at least four times better collective accuracy than that of the
Mass Flow Meter to be calibrated be used. Equipment required for calibration
includes a flow calibration standard and a certified high sensitivity multimeter
(which together have a collective accuracy of ±0.25% or better), an insulated
(plastic) screwdriver, a flow regulator (example: metering needle valve) installed
upstream from the Mass Flow Meter and a pressure regulated source of dry fil-
tered nitrogen gas (or other suitable reference gas).
The gas and ambient temperature, as well as inlet and outlet pressure conditions
should be set up in accordance with actual operating conditions.
13
R52-25%
(IF ENABLED)
R1
J1A (R52)
J1B (R38) J1C (R39) J1D (R40)
R33-SPAN
(25% or 10%)
R34-ZERO
R38-50% R39-75% R40-100%
POWER JACK
D-CONNECTOR
MODULAR JACK
INCREASE
DECREASE
FIGURE 7.a - CALIBRATION POTENTIOMETER AND JUMPER LOCATION S