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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL
5.2.2.2
Gas operated pressure standard with the following characteristics:
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5.2.3
SET-UP AND PREPARATION
5.2.3.1
To set-up and prepare the molbox RFM for calibration of its upstream and
downstream absolute RPTs:
5.2.3.2
To set-up and prepare the molbox RFM for calibration of its microrange
differential RPT:
© 1998-2007 DH Instruments, a Fluke Company
DHI manufactures a variety of pressure standards suitable for calibration of
molbox RFM RPTs. Contact DHI for additional information.
DIFFERENTIAL (MICRORANGE) RPT
Able to apply gauge pressure in 20 % increments between zero and
12.5 kPa (2 psi). It is NOT necessary that the calibration pressure standard
apply precisely the nominal pressure value of each calibration point as long
as the exact value of the applied pressure is known.
Accuracy of ± 2 Pa (0.0003 psi) or better, if best molbox RFM accuracy is
to be obtained. A lower accuracy standard may be used but molbox RFM
accuracy may be degraded from published specifications proportionally.
Use only clean dry gas sources when calibrating molbox RFM RPTs.
Contaminating molbox RFM with liquids can cause out of tolerance
measurements and may require special factory cleaning procedures.
DHI manufactures a variety of pressure standards suitable for calibration of
molbox RFM RPTs. Contact DHI for additional information.
UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS
Set the molbox RFM 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 molbox RFM rear panel
pressure quick connectors and access to the front panel display and keypad.
Connect the calibration standard output to the molbox RFM rear panel
UP (HI) port. In the run calibration mode (see Section 5.2.4.1), both absolute
RPTs are connected to the UP (HI) port and isolated from the DOWN (LO)
port (see Figure 14).
Use one of the quick connector stems (DHI P/N
101889, equivalent to Swagelok SS-QM2-S-200) supplied with the molbox
RFM accessories to make the connection. The fitting on the quick connector
stem that must be mated to is a compression type for 1/8 in. tube.
MICRORANGE DIFFERENTIAL RPT
Set the molbox RFM on a stable surface near the calibration standard.
Consider the connections that need to be made to the molbox RFM rear panel
pressure quick connectors and access to the front panel display and keypad.
Connect the calibration standard output to the molbox RFM rear panel
UP (HI) port.
In the run calibration mode (see Section 5.2.4.1), the
microrange differential RPT high side is connected to the UP (HI) port and
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