Kobold MAS Series, Инструкция по эксплуатации

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MAS Instruction Manual
Page 20
Flow calibration of your MAS requires a calibration standard of at
least double accuracy and preferably an order of magnitude better.
NOTE: The factory calibration of your unit was done to MIL-STD-
45662 A, which has a 4:1 accuracy requirement. Most calibrations
can be done using dry nitrogen and the “K”-factors and gas tables
given in Appendix D. The standard 1.5% calibration of your MAS
is best accomplished with the Kobold Instruments’ Series 100 Cal-
Bench™.
Flow recalibration is performed by using the following procedure.
Please refer to the electrical schematics in Appendix B. Calibration
checks and minor adjustments to the zero and full scale may be
made via the access ports in the side of the enclosure. If the
linearity needs adjustment (as may be required when installing a
different laminar flow element bypass to change the range), go to
STEP 4 through 8. If linearity does not need adjustment, complete
only STEPS 1 through 3.
STEP 1 W
ARM
-U
P
: Plug in the MAS to be calibrated and allow at
least 15 minutes warm-up time before attempting any adjustments.
STEP 2 Z
ERO
A
DJUST
: Slide open the zero and span access ports on
the side of your MAS. Be careful to gently slide open and not bend
back access port covers, as bending back may break covers. Using
a voltmeter connected to the meter output pins, adjust the zero
potentiometer (R5) for zero flow (4 mA for 4-20 mA outputs).
STEP 3 C
HECK
F
ULL
S
CALE
: Generate the full scale flow using a
metering valve in line with the MAS under test. Compare the
indicated flow rate with the flow standard reading. If they agree to
within
±
10%, adjust the span potentiometer (R21) for exact
agreement.
If the readings do not agree within
±
10%, attempt to determine the
cause of disagreement. Possibilities are:
a) Partially clogged or dirty sensor tube
b) Wrong or improper use of “K” factor
c) Wrong or improper correction for temperature and pressure
d) Leaks in the system or in the MAS
e) Replacement of parts in the flow path do not exactly match the
original parts
5
FLOW
CALIBRATION
5.1
General Flow
Calibration Procedure
5.2
Recalibration Over the
Same Flow Range