3. OPERATION
Page 83
© 1998-2007 DH Instruments, a Fluke Company
If there is an active password
, the molbox RFM password entry screen
appears.
The user must enter the user defined
password or the factory
secondary
password to proceed. When a password
is entered correctly, operation proceeds
to the
<1change user level 2edit
password>
screen.
RFM SN nnn-xx
Password: pppppp
The first field,
<
nnnn>,
is the serial number of the molbox RFM, followed by a
second field,
<
xx>,
that counts the number of times that a
secondary
password
has been used. The second field increments each time a
secondary
password
is used. The third field,
<pppppp>
, is for normal password entry.
The factory
secondary
password is available in case the user password has
been misplaced or forgotten. A factory
secondary
password can be obtained by
contacting a
DHI
Authorized Service Provider (see Section 7.2). The factory
secondary
password is different for each molbox RFM and changes each time it is used.
3.6.3
<3UL>
PURPOSE
To set an upper pressure limit above which molbox RFM will produce a warning, interrupt
operation and isolate its internal pressure transducers.
PRINCIPLE
molbox RFM contains two, high precision reference pressure transducers (RPTs). These
can be fatally damaged by large overpressures. The UL function uses molbox RFM's internal
capabilities to attempt to protect the RPTs against overpressure. molbox RFM continuously
monitors the pressure read by the RPTs. When the pressure passes the level set by the UL
function, molbox RFM warns the operator by sounding an audible alarm. Beyond the UL limit
there is an overpressure limit, which is not user selectable. If the pressure reaches the
overpressure limit, molbox RFM uses its internal valves to isolate the RPTs.
OPERATION
To access the Upper Limit (UL) function, press
[SPECIAL]
,
<3ul>
. The display is:
The indication is of the current upper limit setting in
the current pressure unit of measure. To specify a
different pressure unit of measure, use
[SETUP]
,
<2presU>
(see Section 3.5.2).
Transducer Max Pres:
630.000 kPaa
To change the upper limit, enter the value desired (see max UL limits below) and press
[ENTER]
. The display returns to the MAIN run screen with the new upper limit in effect.
The maximum upper limit settings, which are also the default values, are 5 % above the molbox
maximum operating pressure ranges. For molbox RFM, the max UL value is 630 kPa absolute
(91 psia). The overpressure limit, which cannot be edited, is 660 kPa absolute (96 psia)
If the overpressure limit is exceeded, all molbox RFM isolation valves close and normal
operation is interrupted. Normal operation can be reestablished by turning molbox RFM's power
OFF and back ON or pressing
[ENTER]
. Be sure to correct the situation that led to the
overpressure condition prior to rebooting molbox RFM or pressing
[ENTER]
. See Sections
3.6.3.1, 3.1.6 for additional details.
