Omega FMA1800A, Руководство пользователя, Страница: 16 / 36

This practice is recommended when a reference gas is found with thermodynamic
properties similar to the actual gas under consideration. The appropriate relative
correction factor should be recalculated - see section 9. It is standard practice to
calibrate Mass Flow Meters with dry nitrogen gas at 70
0 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 cali-
brations of non-toxic and non-corrosive gases are available at specific conditions.
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 filtered nitro-
gen 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.
12
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 LOCATIONS