Fluke HPMS - Manual (Page 77)

3. OPERATION
Page 67 © 2007 DH Instruments, a Fluke Company
The INTERNAL menu choices include:
<1baro> View the real time output of the RPM4 on-board barometer (see Section
3.5.7.1).
<2ReadRt> Turn ON and OFF RPM4’s automated, rate of change dependent, reading
and integration and display rate feature (see Section 3.5.7.2).
<3RPT2x> Feature not used in this RPM4 model.
<4lo vnt> Feature not used in this RPM4 model.
<5log> View the RPM4 incident log (see Section 3.5.7.5).
3.5.7.1 <1BARO>
 PURPOSE
To view the value of atmospheric pressure as measured by the RPM4 on-board
barometer.
 PRINCIPLE
RPM4 A70M/A20M-AF is equipped with an on-board barometer. The atmospheric
pressure measurements made by the on-board barometer are used for dynamic
compensation of atmospheric pressure when making gauge pressure measurements
(see Sections 3.2.2, 3.3.3,
 PRINCIPLE).
See Section 5.4,4 Figure 13 and Section 5.4.5, Figure 14 for a photo and
schematics showing the position of the on-board barometer in RPM4.
The on-board barometer is a low accuracy sensor used only for measuring
small changes in atmospheric pressure over short periods of time
(see Section 3.2.2). RPM4 measurement uncertainty does not depend on the
measurement uncertainty of the on-board barometer.
 OPERATION
To view the current reading of the on-board barometer press [SPECIAL],
<7internal>, <1baro>. The display is in the active pressure unit of measure
(see Section 3.3.2). The display resolution is fixed to 0.1 Pa, or its equivalent.
3.5.7.2 <2R EAD R T >
 PURPOSE
To turn ON and OFF RPM4’s automated, rate of change dependent, reading
integration and display rate feature.
 PRINCIPLE
To obtain maximum resolution from RPM4 Q-RPT pressure measurements, an
integration time of about 1.2 second per reading is used. In most situations,
maximum precision is needed when pressures are stable so a relatively slow
display update rate presents no disadvantage. However, when pressure is
changing quickly, more rapid pressure updates are usually more important than
obtaining maximum precision on individual readings. The RPM4 read rate
function automatically adjusts pressure measurement integration time depending
on the rate of change of pressure. When pressure is changing rapidly, reading
rate is increased. When pressure is evolving slowly, reading rate is decreased
and maximum precision is obtained.