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A new molbox1+ is delivered with all PA and PM values set to zero
and 1. This does NOT mean that the molbox1+ has NOT been
calibrated.
factory coefficients are used for calibration adjustment. This
allows a new molbox1+ to be delivered with "virgin" calibration
coefficients of PA = 0 and PM = 1.
5.2.2
Equipment Required
To calibrate molbox1+'s absolute reference pressure transducers (RPTs) to factory
specifications, a gas operated pressure standard with the following characteristics
are required:
•
Able to apply absolute pressure in increments between:
•
20 to 300 kPa (3 to 45 psia) for molbox1+ A350K;
•
20 to 600 kPa (3 to 87 psia) for molbox1+ A700K;
•
100 to 1400 kPa (14 to 203 psia) for molbox1+S A1.4M;
•
100 to 2000 kPa (14 to 290 psia) for molbox1+S A2M;
•
It is NOT necessary that the reference pressure standard used apply precisely the
nominal pressure value of the calibration points as long as the exact value of the applied
pressure is known. A different pressure range may be used if it is known that the
molbox1+ will not be used outside of the different range.
•
Measurement uncertainty (accuracy) of ± 0.005 % of reading or better, if normal
molbox1+ flow measurement uncertainty specifications are to be obtained. A standard
with higher measurement uncertainty may be used but molbox1+ flow measurement
uncertainty may be proportionally degraded from published specifications.
Use only a clean dry gas source when calibrating molbox1+ RPTs.
Contaminating molbox1+ with liquids can cause out of tolerance
measurements and may require special factory cleaning.
DHI piston gauge Model PG7601 is recommended as the reference
pressure standard for the calibration of molbox1+ RPTs. Contact DHI or
your local representative for additional information.
5.2.3
Set-Up and Preparation
To set-up and prepare the molbox1+ for calibration:
Set the molbox1+ on a stable surface near the calibration standard at a height as close
as possible to the calibration standard's reference height. Consider the connections that
need to be made to the molbox1+ rear panel pressure quick connectors and access to
the front panel display and keypad.
Connect the calibration standard's output to the molbox1+ rear panel CHANNEL A UP
(HI) and DOWN (LO) ports. In <run> calibration mode (see Section 5.2.4.1), with a
molbox1+ both absolute RPTs are connected to the CHANNEL A UP (HI) port and isolated
from the DOWN (LO) port, but for a molbox1+S the absolute RPTs are independently
connected to the CHANNEL A UP (HI) port and the CHANNEL A DOWN (LO) port. Use the
quick connector stems (DHI P/N 3068652, equivalent to Swagelok SS-QM2-S-200)
supplied with the molbox1+ accessories to make the connection(s). The fitting on the
quick connector stem that must be mated to is a compression type for 1/8 in. tube.
5. MAINTENANCE, ADJUSTMENTS AND CALIBRATION
Note
For the original factory calibration, privileged
Caution
Note
Page 143
© 1995 - 2010 Fluke Corporation, DH Instruments Division
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